Soc Psychiatry Psychiatr Epidemiol DOI 10.1007/s00127-014-0951-8
ORIGINAL PAPER
Loneliness mediates the relationship between childhood trauma and adult psychopathology: evidence from the adult psychiatric morbidity survey Mark Shevlin • Eoin McElroy • Jamie Murphy
Received: 14 March 2014 / Accepted: 28 August 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Childhood abuse (CA) has been found to be related to the development of a variety of psychiatric disorders in adulthood. Although CA is also associated with adult loneliness, few studies have investigated the role of loneliness as a mediator in the relationship between CA and adult psychopathology. Using data from a large, general population sample a mediation model was proposed and tested. Controlling for a range of background variables, the results from a series of regression analyses found that loneliness mediated the association between CA and six adult psychiatric disorders. The findings of this study highlight the importance of loneliness to the development of psychopathology. Theoretical and practical implications are discussed. Keywords Loneliness Childhood abuse Psychopathology Trauma Mediation Childhood abuse (CA) is common, can take many forms and remains a global concern. For example, a recent metaanalysis of 65 general population studies from 22 countries found that 19.7 % of women and 7.9 % of men reported some form childhood sexual abuse [1]. Similarly, it is estimated that between 5.3 and 10.8 % of individuals experience some form of physical abuse during childhood [2]. In the UK, a nationally representative survey (N = 2,275) found that 21.9 % of young people aged 11–17 years reported at least one occurrence of physical, sexual, or emotional abuse, or neglect during childhood [3].
M. Shevlin (&) E. McElroy J. Murphy School of Psychology, Faculty of Life and Health Sciences, University of Ulster at Magee, Londonderry BT48 7JL, Northern Ireland e-mail: [email protected]
Child abuse as a risk factor for adult psychopathology Childhood abuse is a risk factor for the development of a variety of mental health problems in adulthood [4, 5]. Epidemiological studies have identified significant associations between CA and disorders such as depression, generalized anxiety disorder (GAD), mixed anxiety and depression (MAD), phobia, post-traumatic stress disorder (PTSD), and psychosis [6–16]. While CA in general is linked with many psychological disorders, the specificity of this relationship remains unclear. Large-scale general population studies have found little evidence linking specific types of CA with particular disorders [2, 8, 17– 19]. Although the impact of CA on adult mental health may be non-specific, there is some evidence of a dose– response relationship. Both the frequency and severity of CA are positively associated with the increased risk of developing a psychiatric disorder in adulthood [16, 18, 20–22]. Research examining the relationship between CA and adult mental health has often been too narrow in scope, for example studies have tended to examine a single particular form of CA predicting a specific condition [2]. Such methods may be inappropriate given that it is common for multiple forms of CA to occur simultaneously [2, 16, 17, 23]. Studies have shown that individuals who experience more than one type of CA may be at increased risk of developing a psychiatric disorder later in life [17, 24–28]. For instance, a study of a nationally representative British cohort (N = 9,377) followed over a 45-year period found that the risk for mid-life psychological distress increased when multiple forms of CA occurred [29]. Indeed, research suggests that exposure to multiple types of CA may have a more detrimental effect on adult mental health than repeated exposure to one specific type [30, 31].
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Child abuse as a risk factor for adult loneliness Loneliness is a state of negative affectivity arising from the perception that one’s current social needs are not being met by either the quantity or the quality of one’s current social relationships [32]; loneliness refers to perceived social isolation, rather than objective social isolation. Along with the development of psychiatric disorders, there is evidence that CA can lead to feelings of loneliness later in life [33, 34, 35, 36, 21, 17]. Gibson and Hartshorne [37] examined the impact of childhood sexual abuse on adult social networks and loneliness. In a sample of 231 women, they found that a history of CSA was associated with loneliness and poorer social support systems in adulthood. Lev-Wiesel and Sternberg [38] found that in a sample of university students (N = 1,155), childhood physical and emotional abuse predicted greater levels of perceived peer rejection in adulthood. Similarly, Merz and Jak, [39] examined how childhood experiences and close relationships influenced loneliness across the life span in a nationally representative sample of Dutch adults (N = 3,980). They found that stressful childhood events (e.g., parental conflict and parental physical abuse) were significantly associated with loneliness in adulthood.
Loneliness as a risk factor for psychopathology Loneliness itself represents a reliable risk factor for a variety of common mental health problems throughout the life span. Indeed, numerous studies have identified significant associations between feelings of loneliness and depression, GAD, obsessive compulsive disorder, phobia, panic disorder and MAD, and PTSD [35, 40–43]. While social withdrawal is often regarded as a prodromal symptom of psychosis [44], there is a growing body of literature that suggests that social withdrawal prior to the onset of psychosis may influence its development [33, 45–47]. In an attempt to explain the mechanisms by which loneliness impacts mental health, Hawkley and Cacioppo [32] posit a ‘loneliness loop’ model that suggests that feelings of loneliness trigger hypervigilance in individuals which in turn produces cognitive biases (e.g., view social interactions more negatively). These biases create selffulfilling prophecies in which lonely individuals distance themselves from others, yet blame their potential social partners for this distance. As such, they believe their social isolation is beyond their control. This self-reinforcing ‘loneliness loop’ leads to increased feelings of hostility, stress, pessimism, and low self-esteem, which in turn may activate the neurobiological and behavioral mechanisms that lead to the development of psychiatric disorders [32].
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Loneliness as a mediating factor between CA and adult psychopathology Research indicates that loneliness is relatively stable from early childhood through adulthood [48, 49], while many psychiatric disorders emerge in adolescence or adulthood [36]. As such, loneliness represents a plausible mediator by which childhood abuse leads to the development of psychopathology later on in life. Few studies have examined whether loneliness mediates the relationship between CA and adult psychiatric disorders and what little research exists has delivered mixed results. Sperry and Widom [50] conducted a prospective investigation into the mediating role of social support in the relationship between CA and psychopathology in adulthood (N = 754). While they found evidence that social support mediated this relationship, their outcome measures were relatively narrow, focussing solely on depression and anxiety. They also failed to control for re-victimization in adolescence and adulthood, something that is common among CA survivors and which may also lead to mental health problems [3, 51]. Vranceanu, Hobfoll, and Johnson [52] examined whether the relationship between CA and adult psychopathology was mediated by perceived social support in a sample of 100 women. While they found evidence of mediation, their outcome measures were also narrow in scope, focussing solely on depression and PTSD. Other studies have failed to support the idea that social isolation mediates the association between CA and adult psychopathology. Merrill, Thomsen, Sinclair, Gold, and Milner [53] examined the association between CSA, parental support and adult psychological functioning in a sample of 5,226 female navy recruits yet found no effect of parental support on adult adjustment. The discrepancies in the findings could be explained by a number of sampling issues. Research in this area has used disparate samples, often with only female participants. The outcome measures used have also focussed on a small number of psychiatric disorders, which is inappropriate given the non-specific relationship between forms of CA and forms of adult psychiatric disorders. The present study aimed to address these limitations. Using data from a large general population survey (the Adult Psychiatric Morbidity Survey [APMS]) a mediation model was proposed and tested. It was predicted that (1) CA would significantly predict adult psychopathology and loneliness, (2) cumulative childhood physical and sexual abuse would lead to increased risk of psychopathology, and (3) loneliness would mediate the relationship between CA and a variety of adult psychiatric diagnoses.
Soc Psychiatry Psychiatr Epidemiol
Methods Sample The data for the current study was based on the APMS conducted in England in 2007. The APMS was designed to be representative of the population living in private households in England. Using the small users’ postcode address file, the National Centre for Social Research adopted a multi-stage stratified probability sampling design. The survey consisted of a phase one and a phase two (clinical) interview. For phase one of the survey 13,214 potentially eligible private households were identified. One adult aged 16 years or over was selected for interview within each household. Fifty-seven per cent of those who were eligible agreed to take part in an interview which resulted in the completion of 7,403 successful interviews (3,197 males and 4,206 females). The phase one interview contained a section on demographic variables and the assessment of a range of common mental disorders and alcohol and drug use using standardized instruments. The sample had a mean age of 51.12 years (SD = 18.59). To ensure that the results were nationally representative, the data were weighted to account for non-response, gender, age, and region. Details of the survey methods can be found in McManus et al. [54].
Measures Mood and anxiety disorders The Clinical Interview Schedule Revised (CIS-R) [34], a structured clinical interview, was used to generate diagnoses of (1) generalized anxiety disorder (GAD), (2) mixed anxiety and depression disorder (MAD), (3) any phobia, and (4) depressive episode. It is divided into 14 sections based on neurotic symptoms (e.g., depressive ideas, anxiety, sleep disturbances, and fatigue) which assess the presence, frequency, severity, and duration of symptoms over the past week. Scores range from zero to four, apart from depressive ideas, which has a maximum score of five [55]. Diagnoses of disorders are obtained through the application of algorithms reflecting the ICD-10 diagnostic criteria for research [55]. The CIS-R was administered to respondents as part of a computer-assisted self-completion interview (CASI) [54]. The binary diagnostic variables were used in this study. Post-traumatic stress disorder (PTSD) The Trauma Screening Questionnaire (TSQ) was used to establish the prevalence of PTSD. The TSQ consists of 10
yes/no questions regarding the past week occurrence of the DSM-IV [56] specified symptoms of re-experience and arousal [57]. Research indicates that the TSQ is a valid measure of PTSD, independent of trauma type [57]. The TSQ is scored by giving one point to each item endorsed, with a score of six or higher predictive of clinical levels of PTSD [57]. The TSQ was completed by respondents as part of a CASI [54]. Those who suffered a traumatic event after age 16 years and who endorsed more than six items on the TSQ were deemed to have screened positive for PTSD [54]. It must be noted that those who screened positive were not assigned a clinical diagnosis of PTSD, as this would have required full clinical assessments [54]. Psychosis A two-phase procedure was used to make a diagnosis of psychosis. Phase one involved interviews which included questions about (1) anti-psychotic medication, (2) admissions to hospital for mental health reasons, (3) self-reported diagnosis or symptoms of psychosis, and (4) endorsement of the probe and secondary item relating to auditory hallucinations in the Psychosis Screening Questionnaire [58]. The PSQ has been shown to be an effective measure of psychosis in general population [59]. Of the 630 participants who were screened into phase two, 313 met one or more of the psychosis criteria and were, therefore, eligible for a clinical assessment of psychosis. This involved the administration of the Schedule for Assessment in Neuropsychiatry (SCAN) [60] by trained clinical interviewers. Due to initial (N = 64, 20 %) and subsequent refusals (N = 59, 24 %) to take part in phase two, there were 190 participants who completed the SCAN assessment. Identification of a psychotic disorder was based on the results of the SCAN. Subsequently, weighting was used for those who met the phase one criteria for SCAN assessment but did not take part in the assessment to adjust for nonresponse. The binary psychosis variable represented a diagnosis of schizophrenia or affective psychosis in the year prior to the interview based on ICD-10 criteria. Victimization Victimization was assessed using the ‘Domestic Violence and Abuse’ section of the survey. Participants were informed that this section of the interview could potentially cause emotional upset. This section of the interview was self-completed on the computer so the interviewer could not see the responses. Childhood sexual abuse (CSA) was assessed by two questions, ‘‘Before the age of 16, did anyone touch you, or get you to touch them, in a sexual way without your consent?’’ and ‘‘Before the age of 16, did anyone have sexual intercourse with you without your
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consent?’’ A binary variable representing childhood sexual abuse was created that represented the endorsement of either or both of the questions. Childhood physical abuse (CPA) was assessed using responses to the question ‘‘Before the age of 16, were you ever severely beaten by a parent, step-parent, or carer?’’ A four category variable was computed to summarize the CSA and CPA: (1) No CSA or CPA, (2) CPA only, (3) CSA only, and (4) CPA and CSA. Loneliness Loneliness was assessed using a question from the Social Functioning Questionnaire [61]. Respondents were asked to what degree the statement ‘‘I feel lonely and isolated from other people’’ applied to them over the past 2 weeks. Responses were indicated on a four-point Likert scale, ranging from ‘‘1–Not at all’’ to ‘‘4–Very much’’. This question has been used as a measure of loneliness in previous epidemiological studies [42]. Background variables In addition to age and sex, a range of demographic and clinical variables that have been identified as potential risk
factors for general psychopathology were also used in the analysis. These were: Education A variable assessing educational achievement in the survey captured qualifications ranging from no qualifications to degree level and above. This variable was re-coded into a dichotomous variable, which identified respondents as either having attained an educational qualification (1) or not (0). Ethnicity Ethnic background was re-coded into a dichotomous variable, which identified respondents as being of white ethnic origin (1) or of non-white ethnic origin (0). Cannabis use Information about cannabis use was taken from the ‘Drugs’ section of the questionnaire. The questions about drug use were prefixed by ‘‘Have you EVER taken any of the drugs listed below even if it was a long time ago?’’ The first option was ‘‘Cannabis (marijuana, grass, hash, ganja, blow, draw, skunk, weed, and spliff)’’. Answers to this question were coded as yes (1) or no (0). Adult physical and sexual abuse (adult victimization) Questions regarding adult physical and sexual abuse (i.e., abuse suffered aged 16 years or older) came from the ‘Domestic Violence and Abuse’ section of the questionnaire, which was completed confidentially on the Model 3
Loneliness Model 2
Model 1
GAD
MAD
Trauma
Phobia
Depression
PTSD
Psychosis
Covariates
Fig. 1 Model of direct and indirect (via loneliness) effects of trauma on disorders
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computer. Questions focussing on inappropriate sexual touching, rape, assault, bullying, and violence in the home were considered as abuse in adulthood. Abuse in adulthood was recoded into a binary variable where respondents endorsed one or more of the above forms of abuse (1) or no abuse (0) in adulthood.
Analysis A series of regression models were specified and tested to determine if loneliness was a significant mediator of the relationships between childhood trauma and adult psychiatric diagnoses while controlling for background risk factors and adult victimization. The general model is shown in Fig. 1. The model was estimated in three cumulative phases. In phase 1, the four category childhood victimization variable was recoded into three dummy coded variables representing CSA, CPA, and both CSA and CPA. The reference category represented those participants who experienced no childhood trauma. These three dummy coded variables served as the independent variables. The dependent variables were the six psychiatric diagnoses (GAD, MAD, phobia, depressive episode, PTSD, and psychosis). The background risk variables were included at this stage; however, their paths to the mediator and dependent variables were fixed to zero, thereby allowing a Chi square difference test to be conducted. This was a multivariate binary logistic regression model and was estimated in Mplus 6.1 [62] using robust maximum likelihood. In phase 2, the model added the direct paths from the background risk variables (age, sex, education, ethnicity, cannabis use, and adult victimization) to the psychiatric disorder variables. All parameters were estimated simultaneously so that the differences in the estimates for the trauma variables between phase 1 and phase 2 showed the effects of controlling for background risk and adult victimization. In phase 3, the loneliness variable was introduced as a
mediator between the trauma and diagnoses variables. The effects from the trauma variables to the loneliness variable were linear regression estimates and the effects from loneliness to the diagnoses were logistic estimates reported as odds ratios. The adequacy of each phase of the model was assessed using the Akaike Information Criterion (AIC) [63], the Bayesian Information Criterion (BIC) [64], and the samplesize-adjusted Bayesian Information Criterion (ssaBIC) [65] with lower values indicating better model fit. These fit statistics balance model fit with parsimony to determine the optimum model. In addition, Chi-square difference tests were used to determine the best fitting model.
Results The mean loneliness score of respondents was 1.64 (SD = 0.90). A total of 561 respondents reported CSA (7.6 %), 254 reported CPA (3.4 %), while 97 endorsed both CSA and CPA (1.3 %). Table 1 shows the frequencies, percentages, and Chi square statistics of respondents who met the criteria for psychiatric diagnosis by trauma type. Prevalence of psychiatric disorders was highest for both CSA and CPA, and lowest for those who endorsed no CA. Moreover, prevalence of diagnosis was higher for those who reported CPA only compared to those who endorsed CSA only, although these differences were small. The odds ratios (ORs) from the multivariate binary logistic regression analyses are presented in Table 2. Phase 1 estimated the direct effects of the CA variables on the adult psychiatric diagnoses. For this model, the likelihood ratio Chi square was statistically significant (v2 = 164.50, df = 28, p \ 0.01). The addition of the background risk variables (phase 2; Dv2 = 540.04, Ddf = 36, p \ 0.01) and the loneliness mediator variable (phase 3; Dv2 = 1,710.92, Ddf = 15, p \ 0.01) made significant improvements to the overall model (Table 3).
Table 1 Frequencies, percentages, and Chi square statistics of psychiatric diagnoses by trauma type GAD (N = 363)
MAD (N = 676)
Phobia (N = 146)
Depression (N = 207)
PTSD (N = 215)
Psychosis (N = 23)
No CA
264 (4.1 %)
526 (8.1 %)
88 (1.4 %)
140 (2.2 %)
148 (2.3 %)
13 (0.2 %)
CSA
51 (9.1 %)
87 (15.5 %)
23 (4.1 %)
31 (5.5 %)
29 (5.2 %)
4 (0.7 %)
CPA
29 (11.4 %)
41 (16.1 %)
21 (8.3 %)
24 (9.4 %)
25 (9.8 %)
2 (0.8 %)
CSA and CPA
19 (19.6 %)
22 (22.7 %)
14 (14.4 %)
12 (12.4 %)
13 (13.4 %)
4 (4.3 %)
X2(df)
98.80 (3)**
72.26 (3)**
155.87 (3)**
99.22 (3)**
100.45 (3)**
53.93 (3)**
Percentages within trauma type levels No CA no child abuse endorsed, CSA childhood sexual abuse endorsed only, CPA childhood physical abuse endorsed only, CSA and CPA both CPA and CSA endorsed **p \ 0.01
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Soc Psychiatry Psychiatr Epidemiol Table 2 Logistic regression odds ratios and indirect effects (via loneliness) of psychiatric diagnoses by CA and background risk variables Variable
Indirect effect b (S.E.)
Phase 1 OR (95 % CI)
Phase 2 OR (95 % CI)
Phase 3 OR (95 % CI)
CSA
2.39** (1.70–3.37)
1.71** (1.20–2.43)
1.42 (0.99–2.05)
0.203** (0.045)
CPA
3.41** (2.11–5.51)
2.36** (1.44–3.87)
1.55 (0.92–2.61)
0.381** (0.076)
CSA and CPA
6.46** (3.64–11.46)
3.28** (1.79–6.01)
2.21* (1.17–4.20)
Age
–
1.00 (0.99–1.01)
1.00 (0.99–1.01)
-0.003** (0.001)
Sex
–
0.62** (0.48–0.79)
0.71* (0.55–0.92)
-0.112** (0.022)
Ethnicity
–
0.46** (0.31–0.68)
0.48** (0.32–0.72)
-0.081 (0.043)
Qualifications
–
0.67** (0.49– 0.90)
0.79 (0.59– 1.07)
-0.094** (0.027)
Cannabis use
–
1.54** (1.15–2.07)
1.35 (0.99–1.83)
0.161**(0.031)
Re-victimization
–
2.82** (2.16–3.69)
2.10** (1.60–2.76)
0.280**(0.029)
–
–
2.57** (2.26–2.94)
CSA
1.97** (1.50–2.57)
1.43* (1.071–1.90)
1.24 (0.93–1.67)
0.140** (0.031)
CPA
1.74** (1.18–2.58)
1.32 (0.87–2.00)
0.95 (0.60–1.53)
0.263** (0.051)
CSA and CPA
3.01** (1.75–5.16)
1.69 (0.93–3.06)
1.21 (0.66–2.30)
Age
–
0.99** (0.98–0.1.00)
0.99** (0.99–0.99)
Sex
–
0.58** (0.47– 0.70)
0.63** (0.51– 0.77)
Ethnicity
–
0.94 (0.67–1.31)
0.99 (0.70–1.41)
-0.056 (0.030)
Qualifications
–
0.64** (0.51–0.79)
0.69** (0.55–0.875)
-0.065** (0.019)
Cannabis use
–
1.53** (1.22– 1.91)
1.38** (1.09– 1.75)
0.111** (0.022)
Re-victimization
–
2.20** (1.81–2.68)
1.77** (1.44–2.18)
0.193** (0.021)
Loneliness
–
–
1.92** (1.745–2.11)
CSA
3.12** (1.84–5.31)
2.12** (1.22–3.71)
1.66 (0.92–2.99)
0.281** (0.064)
CPA
6.70** (3.79–11.84)
4.98** (2.77–8.96)
2.92** (1.53–5.59)
0.527** (0.107)
CSA and CPA
12.29** (6.04–24.99)
6.40** (2.99–13.42)
3.95** (1.68–9.27)
0.698** (0.160)
Age Sex
– –
0.98** (0.97–0.98) 0.50** (0.33–0.75)
0.98** (0.97–0.99) 0.61 (0.39–0.94)
-0.005** (0.001) -0.155** (0.032)
Ethnicity
–
0.99 (0.50–1.97)
1.14 (0.55–2.38)
-0.113 (0.059)
Qualifications
–
0.60* (0.39–0.93)
0.82 (0.52–1.29)
-0.130** (0.038)
Cannabis use
–
1.16 (0.75–1.80)
0.91 (0.57–1.47)
0.223** (0.044)
Re-victimization
–
2.83** (1.79–4.46)
1.78* (1.09–2.88)
0.388** (0.045)
Loneliness
–
–
3.69** (2.96–4.62)
2.66** (1.68–4.21)
1.92** (1.19–3.10)
1.66 (0.92–2.55)
0.283** (0.064)
CPA
5.38** (3.11–9.29)
3.67** (2.10–6.41)
2.92** (1.23–3.77)
0.531** (0.107)
CSA and CPA
7.41** (3.76–14.96)
3.71** (1.82–7.56)
3.95 (0.97–5.12)
0.703** (0.160)
Age
–
0.99* (0.98–1.00)
0.98 (0.98–1.01)
-0.005** (0.001)
Sex
–
0.67* (0.48–0.94)
0.61 (0.59–1.21)
Ethnicity
–
0.77 (0.43–1.37)
1.14 (0.49–1.59)
-0.113 (0.060)
Qualifications
–
0.47** (0.32– 0.69)
0.82* (0.42– 0.90)
-0.131** (0.131)
Cannabis use Re-victimization
– –
1.24 (0.83–1.85) 3.14** (2.14–4.59)
0.91 (0.65–1.52) 1.78** (1.40–3.01)
0.225** (0.044) 0.391** (0.043)
Loneliness
–
–
3.69** (3.04–4.57)
2.22** (1.411–3.51)
1.63* (1.00–2.64)
1.32 (0.80–2.18)
0.232** (0.052)
CPA
5.54** (3.27–9.39)
3.79** (2.22–6.47)
2.41** (1.37–4.23)
0.436** (0.089)
CSA and CPA
5.55** (2.59–12.04)
2.74* (1.22–6.14)
1.73 (0.76–3.96)
0.577** (0.133)
GAD
Loneliness MAD
0.504** (0.113)
0.348** (0.791) -0.002** (0.000) 0.077** (0.015)
Phobia
Depression CSA
0.156** (0.032)
PTSD CSA
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Soc Psychiatry Psychiatr Epidemiol Table 2 continued Phase 1 OR (95 % CI)
Phase 2 OR (95 % CI)
Phase 3 OR (95 % CI)
Indirect effect b (S.E.)
Age
–
0.97** (0.96–0.98)
0.98** (0.97–0.98)
-0.004**(0.001)
Sex
–
0.78 (0.56–1.08)
0.94 (0.67–1.32)
0.128**(0.026)
Ethnicity Qualifications
– –
0.91 (0.52–1.60) 0.50** (0.35–0.72)
1.03 (0.59–1.81) 0.61* (0.42–0.90)
-0.093 (0.049) -0.107** (0.032)
Cannabis use
–
1.03 (0.70–1.51)
0.82 (0.54–1.22)
0.184** (0.036)
Re-victimization
–
3.31** (2.27–4.83)
2.28** (1.55–3.34)
0.320** (0.036)
Loneliness
–
–
2.94** (2.48–3.50)
CSA
2.68 (0.83–8.69)
1.60 (0.5–5.14)
1.25 (0.39–3.98)
0.291** (0.098)
CPA
4.44 (0.95–20.69)
2.55 (0.54–11.99)
1.31 (0.29–5.88)
0.546** (0.175)
CSA and CPA
19.55** (6.00–63.70)
7.00** (1.96–25.05)
3.81* (1.07–13.61)
Age
–
0.99 (0.97–1.00)
0.99 (0.97–1.02)
-0.005** (0.002)
Sex
–
0.57 (0.21–1.50)
0.72 (0.26–2.05)
-0.161** (0.051)
Ethnicity
–
0.71 (0.20–2.52)
0.69 (0.21–2.35)
-0.117 (0.068)
Qualifications
–
0.44 (0.15–1.30)
0.61 (0.19–1.98)
-0.134* (0.053)
Cannabis use
–
1.79 (0.69–4.67)
1.47 (0.52–4.17)
0.231** (0.072)
Re-victimization
–
6.22** (2.00–19.31)
4.02* (1.24–13.08)
0.401** (0.111)
Loneliness
–
–
3.87** (1.93–7.76)
Variable
Psychosis
0.722** (0.242)
CSA childhood sexual abuse endorsed only, CPA childhood physical abuse endorsed only, CSA and CPA both CPA and CSA endorsed, b beta coefficient, S.E. standard error ** p \ 0.01; * p \ 0.05
Table 3 Fit indices for the mediation model Model
Loglikelihood
# Free parameters
AIC
BIC
ssaBIC
Phase 1
-24,709
28
49,474
49,667
49,578
Phase 2
-24,439
64
49,006
49,447
49,244
Phase 3
-23,584
79
47,325
47,870
47,619
AIC Akaike information criterion, BIC Bayesian information criterion, ssaBIC sample-size-adjusted BIC
In phase 1, the three CA variables significantly predicted each psychiatric diagnosis, except in the case of psychosis where only the combined CSA and CPA variable had a statistically significant association. For each diagnosis, the effects were highest for the combined CSA and CPA variable, with ORs ranging from 3.01 for MAD to 19.55 for psychosis. The effects were generally higher for CPA compared to CSA, with ORs ranging from 1.74 for MAD to 6.70 for phobia. The introduction of the background variables in phase 2 resulted in an overall decrease in the ORs. Once these variables were introduced, the effects of CPA and combined CSA and CPA on MAD were no longer statistically significant. The biggest decrease in ORs was for psychosis (from 19.55 to 7.00). The smallest decrease in ORs was for MAD in the CSA group (from 1.97 to 1.43). In phase 3, adult loneliness was predicted by CSA (b = 0.25, SE = 0.05, p \ 0.01), CPA (b = 0.46,
SE = 0.08, p \ 0.01), combined CSA and CPA (b = 0.610, SE = 0.131, p \ 0.01), age (b = -0.004, SE = 0.001, p \ 0.01), sex (b = 0.135, SE = 0.03, p \ 0.01), qualifications (b = 0.11, SE = 0.03, p \ 0.01), lifetime cannabis use (b = 0.195, SE = 0.04, p \ 0.01) and re-victimization (b = 0.34, SE = 0.03, p \ 0.01). The loneliness variable significantly predicted each of the adult psychiatric diagnoses, with ORs ranging from 1.92 (95 % CI 1.745–2.11) for MAD to 3.87 (95 % CI 1.93–7.76) for psychosis. The products of the direct paths between the CA variables and the mediator variable, and the mediator variable and the psychiatric diagnoses variables are presented in Table 2. These indirect effects (via loneliness) for each of the CA variables on each psychiatric diagnosis were statistically significant. Also, the introduction of this mediator led to an overall reduction in the ORs for the direct effects between CA and the diagnosis variables. On the basis of these estimates, and the Chi square difference
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test which indicated that the introduction of the loneliness variable significantly improved the model, it was concluded that loneliness was a significant mediator between CA and the psychiatric disorders.
Discussion The present study aimed to (1) examine whether CA was significantly associated with adult loneliness and psychopathology, (2) examine whether cumulative CSA and CPA were associated with greater levels of psychopathology and loneliness compared to CSA or CPA alone, and (3) test whether loneliness mediated the relationship between CA and six adult psychiatric disorders. The CA variables significantly predicted all six of the adult psychiatric diagnoses and adult loneliness; therefore, the first hypothesis was supported. These findings were consistent with a large body of evidence that links CA with the development of psychopathology and loneliness in adulthood [8, 13, 14, 16, 38, 39, 66, 67]. An examination of the ORs indicated that the likelihood of meeting the diagnostic criteria of GAD, phobia, and psychosis was higher for those who reported both CSA and CPA. In cases of MAD, depression and PTSD, however, this pattern was not observed. As such, the second hypothesis was only partially supported. This finding appears to contradict previous research which suggests that exposure to multiple forms of CA is more detrimental to adult mental health than repeated exposure to one specific type [30, 31]. It must be noted, however, that the present study did not take the frequency and severity of CA into account. As such, it was not possible to make direct comparisons between multiple forms of CA and sustained single forms of CA. Further research, taking frequency and severity of CA into account, may be required to properly compare these forms of CA. The introduction of the loneliness mediator variable led to a reduction in the direct effects of CSA only and CPA only on six of the psychiatric diagnoses. For most of the diagnoses these effects became statistically non-significant, suggesting full mediation. The introduction of this variable saw a reduction in effects at the combined CSA and CPA level; however, the effects at this level remained statistically significant for most of the diagnoses, suggesting partial mediation. Overall, this provides broad support for the third hypothesis. These results are consistent with previous research which has found similar mediated effects [50, 52]. The present study expands upon this previous work by including a variety of adult psychiatric diagnoses, using a large general population sample of both males and females, and controlling for revictimization in adulthood.
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Limitations The above findings should be considered in light of the following limitations. First, as cross-sectional data were used, the temporal ordering of loneliness and psychiatric disorders cannot be unequivocally determined. However, research indicates that loneliness is relatively stable across the life span [48, 49], while the past year diagnoses reported in the APMS peaked at the age group 45–54 years for women and 25–54 years for men [54]. As such, it is likely the feelings of loneliness preceded these diagnoses. Further research employing a fully longitudinal design is required before firm causal inferences can be made (see Maxwell & Cole, [68]). Second, loneliness was measured by a single item. While this measure of loneliness has been used in previous epidemiological research [42], single item measures may have poorer validity and reliability compared to multi-item scales, resulting in attenuated statistical associations. Also, research has indicated that males tend to under-report loneliness when single item scales are used [69], although gender was included as a covariate in the present analysis to statistically control for this effect. Third, as the mean age was 51.12 years, the reliability of respondent’s reports of CA could be questioned. However, research indicates that retrospective recall is an acceptable method for measuring childhood trauma such as physical or sexual abuse as it is more likely to result in the underreporting of CA rather than over-reporting [70]. Fourth, the frequency and severity of CA, beyond the co-occurrence of CSA and CPA, was not assessed. This could have had a confounding effect on the results given that research suggests a dose–response relationship between CA and adult psychopathology [16, 18, 20–22]. Also, reports of CPA were restricted to abuse at the hands of parents or caregivers. This excludes physical abuse from other potential sources (e.g., peers) which has been shown to have a deleterious effect on adult mental health [71, 72]. Theoretical and practical implications The results of this study have both theoretical and clinical implications. Although this paper did not aim to explicitly test the ‘loneliness loop’ model proposed by Hawkley and Cacioppo [32], the present findings compliment this theoretical framework. This model suggests that feelings of loneliness may trigger hypervigilance regarding the social environment. This in turn produces cognitive biases and self-fulfilling prophecies which cause distress, and which may eventually lead to the development of psychiatric disorders [32]. Introducing CA to this framework builds upon this model; along with the direct effects of CA on the development of adult psychopathology, CA may also have an indirect effect on psychopathology through loneliness
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Fig. 2 Graphical illustration of CA within the ‘loneliness loop’ framework proposed by Hawkley and Cacioppo (2010)
(Fig. 2). It is possible that CA precedes and leads to the initial feelings of loneliness. CA survivors may perceive the social world as more threatening than others, causing them to become more socially withdrawn and lonely. This in turn may lead to the cognitive biases and self-fulfilling prophecies that constitute the ‘loneliness loop’. This selfreinforcing loop may ultimately lead to the development of psychopathology. Further research using longitudinal data would be required to properly test this model. In relation to psychosis, the findings from this study fit within the social deafferentation framework. The social deafferentation hypothesis posits that prolonged social withdrawal may lead to the development of social cognition programmes which produce false social meaning in the form of hallucinations and/or delusions [45]. Recent research has taken this idea a step further, suggesting that subjective rather than objective social isolation may be influential in the development of psychosis [33]. Indeed, in an analysis of the British Psychiatric Morbidity Survey (BPMS; N = 8,580) Murphy and colleagues [33] found that avoidant personality traits mediated the relationship between childhood trauma and psychosis, while selfreported social contact did not. The findings from the present study corroborate the work of Murphy and colleagues [33] and suggest that subjective feelings of social isolation, in this case characterized by loneliness, may be influential in the development of psychosis. It is important to note that many societal and life events are associated with the development of loneliness, such as advancing age, widowhood, and low level of education [73]. The present study focussed on one particular antecedent of loneliness; CA. Further research could be required to establish whether such trauma-based loneliness represents a greater threat to adult mental health than other forms of loneliness. The findings from this study highlight the importance of adequate social relationships for individuals presenting
with mental health problems. At the assessment level, clinicians should be encouraged to consider the individual’s perceived level of social isolation, rather than their objective level of social isolation. An accurate assessment of social needs could lead to the development of social conditioning interventions aimed at reducing feelings of loneliness (e.g., access to work, education, recreation, social skills training, and improved access to meaningful activities). Such interventions could lead to more meaningful social relationships and reduced feelings of loneliness. This in turn may lead to positive outcomes across a variety of mental health problems.
Conclusion The present study examined whether loneliness mediated the relationship between CA and adult psychopathology in a large general population sample. Results indicated that loneliness was a significant mediator in the relationship between CA and six adult psychiatric diagnoses. Although limited by the cross-sectional nature of the data, this study highlights the theoretical and clinical importance of loneliness to the development of psychopathology. Further research using longitudinal designs is recommended.
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ORIGINAL PAPER
Loneliness mediates the relationship between childhood trauma and adult psychopathology: evidence from the adult psychiatric morbidity survey Mark Shevlin • Eoin McElroy • Jamie Murphy
Received: 14 March 2014 / Accepted: 28 August 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Childhood abuse (CA) has been found to be related to the development of a variety of psychiatric disorders in adulthood. Although CA is also associated with adult loneliness, few studies have investigated the role of loneliness as a mediator in the relationship between CA and adult psychopathology. Using data from a large, general population sample a mediation model was proposed and tested. Controlling for a range of background variables, the results from a series of regression analyses found that loneliness mediated the association between CA and six adult psychiatric disorders. The findings of this study highlight the importance of loneliness to the development of psychopathology. Theoretical and practical implications are discussed. Keywords Loneliness Childhood abuse Psychopathology Trauma Mediation Childhood abuse (CA) is common, can take many forms and remains a global concern. For example, a recent metaanalysis of 65 general population studies from 22 countries found that 19.7 % of women and 7.9 % of men reported some form childhood sexual abuse [1]. Similarly, it is estimated that between 5.3 and 10.8 % of individuals experience some form of physical abuse during childhood [2]. In the UK, a nationally representative survey (N = 2,275) found that 21.9 % of young people aged 11–17 years reported at least one occurrence of physical, sexual, or emotional abuse, or neglect during childhood [3].
M. Shevlin (&) E. McElroy J. Murphy School of Psychology, Faculty of Life and Health Sciences, University of Ulster at Magee, Londonderry BT48 7JL, Northern Ireland e-mail: [email protected]
Child abuse as a risk factor for adult psychopathology Childhood abuse is a risk factor for the development of a variety of mental health problems in adulthood [4, 5]. Epidemiological studies have identified significant associations between CA and disorders such as depression, generalized anxiety disorder (GAD), mixed anxiety and depression (MAD), phobia, post-traumatic stress disorder (PTSD), and psychosis [6–16]. While CA in general is linked with many psychological disorders, the specificity of this relationship remains unclear. Large-scale general population studies have found little evidence linking specific types of CA with particular disorders [2, 8, 17– 19]. Although the impact of CA on adult mental health may be non-specific, there is some evidence of a dose– response relationship. Both the frequency and severity of CA are positively associated with the increased risk of developing a psychiatric disorder in adulthood [16, 18, 20–22]. Research examining the relationship between CA and adult mental health has often been too narrow in scope, for example studies have tended to examine a single particular form of CA predicting a specific condition [2]. Such methods may be inappropriate given that it is common for multiple forms of CA to occur simultaneously [2, 16, 17, 23]. Studies have shown that individuals who experience more than one type of CA may be at increased risk of developing a psychiatric disorder later in life [17, 24–28]. For instance, a study of a nationally representative British cohort (N = 9,377) followed over a 45-year period found that the risk for mid-life psychological distress increased when multiple forms of CA occurred [29]. Indeed, research suggests that exposure to multiple types of CA may have a more detrimental effect on adult mental health than repeated exposure to one specific type [30, 31].
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Child abuse as a risk factor for adult loneliness Loneliness is a state of negative affectivity arising from the perception that one’s current social needs are not being met by either the quantity or the quality of one’s current social relationships [32]; loneliness refers to perceived social isolation, rather than objective social isolation. Along with the development of psychiatric disorders, there is evidence that CA can lead to feelings of loneliness later in life [33, 34, 35, 36, 21, 17]. Gibson and Hartshorne [37] examined the impact of childhood sexual abuse on adult social networks and loneliness. In a sample of 231 women, they found that a history of CSA was associated with loneliness and poorer social support systems in adulthood. Lev-Wiesel and Sternberg [38] found that in a sample of university students (N = 1,155), childhood physical and emotional abuse predicted greater levels of perceived peer rejection in adulthood. Similarly, Merz and Jak, [39] examined how childhood experiences and close relationships influenced loneliness across the life span in a nationally representative sample of Dutch adults (N = 3,980). They found that stressful childhood events (e.g., parental conflict and parental physical abuse) were significantly associated with loneliness in adulthood.
Loneliness as a risk factor for psychopathology Loneliness itself represents a reliable risk factor for a variety of common mental health problems throughout the life span. Indeed, numerous studies have identified significant associations between feelings of loneliness and depression, GAD, obsessive compulsive disorder, phobia, panic disorder and MAD, and PTSD [35, 40–43]. While social withdrawal is often regarded as a prodromal symptom of psychosis [44], there is a growing body of literature that suggests that social withdrawal prior to the onset of psychosis may influence its development [33, 45–47]. In an attempt to explain the mechanisms by which loneliness impacts mental health, Hawkley and Cacioppo [32] posit a ‘loneliness loop’ model that suggests that feelings of loneliness trigger hypervigilance in individuals which in turn produces cognitive biases (e.g., view social interactions more negatively). These biases create selffulfilling prophecies in which lonely individuals distance themselves from others, yet blame their potential social partners for this distance. As such, they believe their social isolation is beyond their control. This self-reinforcing ‘loneliness loop’ leads to increased feelings of hostility, stress, pessimism, and low self-esteem, which in turn may activate the neurobiological and behavioral mechanisms that lead to the development of psychiatric disorders [32].
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Loneliness as a mediating factor between CA and adult psychopathology Research indicates that loneliness is relatively stable from early childhood through adulthood [48, 49], while many psychiatric disorders emerge in adolescence or adulthood [36]. As such, loneliness represents a plausible mediator by which childhood abuse leads to the development of psychopathology later on in life. Few studies have examined whether loneliness mediates the relationship between CA and adult psychiatric disorders and what little research exists has delivered mixed results. Sperry and Widom [50] conducted a prospective investigation into the mediating role of social support in the relationship between CA and psychopathology in adulthood (N = 754). While they found evidence that social support mediated this relationship, their outcome measures were relatively narrow, focussing solely on depression and anxiety. They also failed to control for re-victimization in adolescence and adulthood, something that is common among CA survivors and which may also lead to mental health problems [3, 51]. Vranceanu, Hobfoll, and Johnson [52] examined whether the relationship between CA and adult psychopathology was mediated by perceived social support in a sample of 100 women. While they found evidence of mediation, their outcome measures were also narrow in scope, focussing solely on depression and PTSD. Other studies have failed to support the idea that social isolation mediates the association between CA and adult psychopathology. Merrill, Thomsen, Sinclair, Gold, and Milner [53] examined the association between CSA, parental support and adult psychological functioning in a sample of 5,226 female navy recruits yet found no effect of parental support on adult adjustment. The discrepancies in the findings could be explained by a number of sampling issues. Research in this area has used disparate samples, often with only female participants. The outcome measures used have also focussed on a small number of psychiatric disorders, which is inappropriate given the non-specific relationship between forms of CA and forms of adult psychiatric disorders. The present study aimed to address these limitations. Using data from a large general population survey (the Adult Psychiatric Morbidity Survey [APMS]) a mediation model was proposed and tested. It was predicted that (1) CA would significantly predict adult psychopathology and loneliness, (2) cumulative childhood physical and sexual abuse would lead to increased risk of psychopathology, and (3) loneliness would mediate the relationship between CA and a variety of adult psychiatric diagnoses.
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Methods Sample The data for the current study was based on the APMS conducted in England in 2007. The APMS was designed to be representative of the population living in private households in England. Using the small users’ postcode address file, the National Centre for Social Research adopted a multi-stage stratified probability sampling design. The survey consisted of a phase one and a phase two (clinical) interview. For phase one of the survey 13,214 potentially eligible private households were identified. One adult aged 16 years or over was selected for interview within each household. Fifty-seven per cent of those who were eligible agreed to take part in an interview which resulted in the completion of 7,403 successful interviews (3,197 males and 4,206 females). The phase one interview contained a section on demographic variables and the assessment of a range of common mental disorders and alcohol and drug use using standardized instruments. The sample had a mean age of 51.12 years (SD = 18.59). To ensure that the results were nationally representative, the data were weighted to account for non-response, gender, age, and region. Details of the survey methods can be found in McManus et al. [54].
Measures Mood and anxiety disorders The Clinical Interview Schedule Revised (CIS-R) [34], a structured clinical interview, was used to generate diagnoses of (1) generalized anxiety disorder (GAD), (2) mixed anxiety and depression disorder (MAD), (3) any phobia, and (4) depressive episode. It is divided into 14 sections based on neurotic symptoms (e.g., depressive ideas, anxiety, sleep disturbances, and fatigue) which assess the presence, frequency, severity, and duration of symptoms over the past week. Scores range from zero to four, apart from depressive ideas, which has a maximum score of five [55]. Diagnoses of disorders are obtained through the application of algorithms reflecting the ICD-10 diagnostic criteria for research [55]. The CIS-R was administered to respondents as part of a computer-assisted self-completion interview (CASI) [54]. The binary diagnostic variables were used in this study. Post-traumatic stress disorder (PTSD) The Trauma Screening Questionnaire (TSQ) was used to establish the prevalence of PTSD. The TSQ consists of 10
yes/no questions regarding the past week occurrence of the DSM-IV [56] specified symptoms of re-experience and arousal [57]. Research indicates that the TSQ is a valid measure of PTSD, independent of trauma type [57]. The TSQ is scored by giving one point to each item endorsed, with a score of six or higher predictive of clinical levels of PTSD [57]. The TSQ was completed by respondents as part of a CASI [54]. Those who suffered a traumatic event after age 16 years and who endorsed more than six items on the TSQ were deemed to have screened positive for PTSD [54]. It must be noted that those who screened positive were not assigned a clinical diagnosis of PTSD, as this would have required full clinical assessments [54]. Psychosis A two-phase procedure was used to make a diagnosis of psychosis. Phase one involved interviews which included questions about (1) anti-psychotic medication, (2) admissions to hospital for mental health reasons, (3) self-reported diagnosis or symptoms of psychosis, and (4) endorsement of the probe and secondary item relating to auditory hallucinations in the Psychosis Screening Questionnaire [58]. The PSQ has been shown to be an effective measure of psychosis in general population [59]. Of the 630 participants who were screened into phase two, 313 met one or more of the psychosis criteria and were, therefore, eligible for a clinical assessment of psychosis. This involved the administration of the Schedule for Assessment in Neuropsychiatry (SCAN) [60] by trained clinical interviewers. Due to initial (N = 64, 20 %) and subsequent refusals (N = 59, 24 %) to take part in phase two, there were 190 participants who completed the SCAN assessment. Identification of a psychotic disorder was based on the results of the SCAN. Subsequently, weighting was used for those who met the phase one criteria for SCAN assessment but did not take part in the assessment to adjust for nonresponse. The binary psychosis variable represented a diagnosis of schizophrenia or affective psychosis in the year prior to the interview based on ICD-10 criteria. Victimization Victimization was assessed using the ‘Domestic Violence and Abuse’ section of the survey. Participants were informed that this section of the interview could potentially cause emotional upset. This section of the interview was self-completed on the computer so the interviewer could not see the responses. Childhood sexual abuse (CSA) was assessed by two questions, ‘‘Before the age of 16, did anyone touch you, or get you to touch them, in a sexual way without your consent?’’ and ‘‘Before the age of 16, did anyone have sexual intercourse with you without your
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consent?’’ A binary variable representing childhood sexual abuse was created that represented the endorsement of either or both of the questions. Childhood physical abuse (CPA) was assessed using responses to the question ‘‘Before the age of 16, were you ever severely beaten by a parent, step-parent, or carer?’’ A four category variable was computed to summarize the CSA and CPA: (1) No CSA or CPA, (2) CPA only, (3) CSA only, and (4) CPA and CSA. Loneliness Loneliness was assessed using a question from the Social Functioning Questionnaire [61]. Respondents were asked to what degree the statement ‘‘I feel lonely and isolated from other people’’ applied to them over the past 2 weeks. Responses were indicated on a four-point Likert scale, ranging from ‘‘1–Not at all’’ to ‘‘4–Very much’’. This question has been used as a measure of loneliness in previous epidemiological studies [42]. Background variables In addition to age and sex, a range of demographic and clinical variables that have been identified as potential risk
factors for general psychopathology were also used in the analysis. These were: Education A variable assessing educational achievement in the survey captured qualifications ranging from no qualifications to degree level and above. This variable was re-coded into a dichotomous variable, which identified respondents as either having attained an educational qualification (1) or not (0). Ethnicity Ethnic background was re-coded into a dichotomous variable, which identified respondents as being of white ethnic origin (1) or of non-white ethnic origin (0). Cannabis use Information about cannabis use was taken from the ‘Drugs’ section of the questionnaire. The questions about drug use were prefixed by ‘‘Have you EVER taken any of the drugs listed below even if it was a long time ago?’’ The first option was ‘‘Cannabis (marijuana, grass, hash, ganja, blow, draw, skunk, weed, and spliff)’’. Answers to this question were coded as yes (1) or no (0). Adult physical and sexual abuse (adult victimization) Questions regarding adult physical and sexual abuse (i.e., abuse suffered aged 16 years or older) came from the ‘Domestic Violence and Abuse’ section of the questionnaire, which was completed confidentially on the Model 3
Loneliness Model 2
Model 1
GAD
MAD
Trauma
Phobia
Depression
PTSD
Psychosis
Covariates
Fig. 1 Model of direct and indirect (via loneliness) effects of trauma on disorders
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computer. Questions focussing on inappropriate sexual touching, rape, assault, bullying, and violence in the home were considered as abuse in adulthood. Abuse in adulthood was recoded into a binary variable where respondents endorsed one or more of the above forms of abuse (1) or no abuse (0) in adulthood.
Analysis A series of regression models were specified and tested to determine if loneliness was a significant mediator of the relationships between childhood trauma and adult psychiatric diagnoses while controlling for background risk factors and adult victimization. The general model is shown in Fig. 1. The model was estimated in three cumulative phases. In phase 1, the four category childhood victimization variable was recoded into three dummy coded variables representing CSA, CPA, and both CSA and CPA. The reference category represented those participants who experienced no childhood trauma. These three dummy coded variables served as the independent variables. The dependent variables were the six psychiatric diagnoses (GAD, MAD, phobia, depressive episode, PTSD, and psychosis). The background risk variables were included at this stage; however, their paths to the mediator and dependent variables were fixed to zero, thereby allowing a Chi square difference test to be conducted. This was a multivariate binary logistic regression model and was estimated in Mplus 6.1 [62] using robust maximum likelihood. In phase 2, the model added the direct paths from the background risk variables (age, sex, education, ethnicity, cannabis use, and adult victimization) to the psychiatric disorder variables. All parameters were estimated simultaneously so that the differences in the estimates for the trauma variables between phase 1 and phase 2 showed the effects of controlling for background risk and adult victimization. In phase 3, the loneliness variable was introduced as a
mediator between the trauma and diagnoses variables. The effects from the trauma variables to the loneliness variable were linear regression estimates and the effects from loneliness to the diagnoses were logistic estimates reported as odds ratios. The adequacy of each phase of the model was assessed using the Akaike Information Criterion (AIC) [63], the Bayesian Information Criterion (BIC) [64], and the samplesize-adjusted Bayesian Information Criterion (ssaBIC) [65] with lower values indicating better model fit. These fit statistics balance model fit with parsimony to determine the optimum model. In addition, Chi-square difference tests were used to determine the best fitting model.
Results The mean loneliness score of respondents was 1.64 (SD = 0.90). A total of 561 respondents reported CSA (7.6 %), 254 reported CPA (3.4 %), while 97 endorsed both CSA and CPA (1.3 %). Table 1 shows the frequencies, percentages, and Chi square statistics of respondents who met the criteria for psychiatric diagnosis by trauma type. Prevalence of psychiatric disorders was highest for both CSA and CPA, and lowest for those who endorsed no CA. Moreover, prevalence of diagnosis was higher for those who reported CPA only compared to those who endorsed CSA only, although these differences were small. The odds ratios (ORs) from the multivariate binary logistic regression analyses are presented in Table 2. Phase 1 estimated the direct effects of the CA variables on the adult psychiatric diagnoses. For this model, the likelihood ratio Chi square was statistically significant (v2 = 164.50, df = 28, p \ 0.01). The addition of the background risk variables (phase 2; Dv2 = 540.04, Ddf = 36, p \ 0.01) and the loneliness mediator variable (phase 3; Dv2 = 1,710.92, Ddf = 15, p \ 0.01) made significant improvements to the overall model (Table 3).
Table 1 Frequencies, percentages, and Chi square statistics of psychiatric diagnoses by trauma type GAD (N = 363)
MAD (N = 676)
Phobia (N = 146)
Depression (N = 207)
PTSD (N = 215)
Psychosis (N = 23)
No CA
264 (4.1 %)
526 (8.1 %)
88 (1.4 %)
140 (2.2 %)
148 (2.3 %)
13 (0.2 %)
CSA
51 (9.1 %)
87 (15.5 %)
23 (4.1 %)
31 (5.5 %)
29 (5.2 %)
4 (0.7 %)
CPA
29 (11.4 %)
41 (16.1 %)
21 (8.3 %)
24 (9.4 %)
25 (9.8 %)
2 (0.8 %)
CSA and CPA
19 (19.6 %)
22 (22.7 %)
14 (14.4 %)
12 (12.4 %)
13 (13.4 %)
4 (4.3 %)
X2(df)
98.80 (3)**
72.26 (3)**
155.87 (3)**
99.22 (3)**
100.45 (3)**
53.93 (3)**
Percentages within trauma type levels No CA no child abuse endorsed, CSA childhood sexual abuse endorsed only, CPA childhood physical abuse endorsed only, CSA and CPA both CPA and CSA endorsed **p \ 0.01
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Soc Psychiatry Psychiatr Epidemiol Table 2 Logistic regression odds ratios and indirect effects (via loneliness) of psychiatric diagnoses by CA and background risk variables Variable
Indirect effect b (S.E.)
Phase 1 OR (95 % CI)
Phase 2 OR (95 % CI)
Phase 3 OR (95 % CI)
CSA
2.39** (1.70–3.37)
1.71** (1.20–2.43)
1.42 (0.99–2.05)
0.203** (0.045)
CPA
3.41** (2.11–5.51)
2.36** (1.44–3.87)
1.55 (0.92–2.61)
0.381** (0.076)
CSA and CPA
6.46** (3.64–11.46)
3.28** (1.79–6.01)
2.21* (1.17–4.20)
Age
–
1.00 (0.99–1.01)
1.00 (0.99–1.01)
-0.003** (0.001)
Sex
–
0.62** (0.48–0.79)
0.71* (0.55–0.92)
-0.112** (0.022)
Ethnicity
–
0.46** (0.31–0.68)
0.48** (0.32–0.72)
-0.081 (0.043)
Qualifications
–
0.67** (0.49– 0.90)
0.79 (0.59– 1.07)
-0.094** (0.027)
Cannabis use
–
1.54** (1.15–2.07)
1.35 (0.99–1.83)
0.161**(0.031)
Re-victimization
–
2.82** (2.16–3.69)
2.10** (1.60–2.76)
0.280**(0.029)
–
–
2.57** (2.26–2.94)
CSA
1.97** (1.50–2.57)
1.43* (1.071–1.90)
1.24 (0.93–1.67)
0.140** (0.031)
CPA
1.74** (1.18–2.58)
1.32 (0.87–2.00)
0.95 (0.60–1.53)
0.263** (0.051)
CSA and CPA
3.01** (1.75–5.16)
1.69 (0.93–3.06)
1.21 (0.66–2.30)
Age
–
0.99** (0.98–0.1.00)
0.99** (0.99–0.99)
Sex
–
0.58** (0.47– 0.70)
0.63** (0.51– 0.77)
Ethnicity
–
0.94 (0.67–1.31)
0.99 (0.70–1.41)
-0.056 (0.030)
Qualifications
–
0.64** (0.51–0.79)
0.69** (0.55–0.875)
-0.065** (0.019)
Cannabis use
–
1.53** (1.22– 1.91)
1.38** (1.09– 1.75)
0.111** (0.022)
Re-victimization
–
2.20** (1.81–2.68)
1.77** (1.44–2.18)
0.193** (0.021)
Loneliness
–
–
1.92** (1.745–2.11)
CSA
3.12** (1.84–5.31)
2.12** (1.22–3.71)
1.66 (0.92–2.99)
0.281** (0.064)
CPA
6.70** (3.79–11.84)
4.98** (2.77–8.96)
2.92** (1.53–5.59)
0.527** (0.107)
CSA and CPA
12.29** (6.04–24.99)
6.40** (2.99–13.42)
3.95** (1.68–9.27)
0.698** (0.160)
Age Sex
– –
0.98** (0.97–0.98) 0.50** (0.33–0.75)
0.98** (0.97–0.99) 0.61 (0.39–0.94)
-0.005** (0.001) -0.155** (0.032)
Ethnicity
–
0.99 (0.50–1.97)
1.14 (0.55–2.38)
-0.113 (0.059)
Qualifications
–
0.60* (0.39–0.93)
0.82 (0.52–1.29)
-0.130** (0.038)
Cannabis use
–
1.16 (0.75–1.80)
0.91 (0.57–1.47)
0.223** (0.044)
Re-victimization
–
2.83** (1.79–4.46)
1.78* (1.09–2.88)
0.388** (0.045)
Loneliness
–
–
3.69** (2.96–4.62)
2.66** (1.68–4.21)
1.92** (1.19–3.10)
1.66 (0.92–2.55)
0.283** (0.064)
CPA
5.38** (3.11–9.29)
3.67** (2.10–6.41)
2.92** (1.23–3.77)
0.531** (0.107)
CSA and CPA
7.41** (3.76–14.96)
3.71** (1.82–7.56)
3.95 (0.97–5.12)
0.703** (0.160)
Age
–
0.99* (0.98–1.00)
0.98 (0.98–1.01)
-0.005** (0.001)
Sex
–
0.67* (0.48–0.94)
0.61 (0.59–1.21)
Ethnicity
–
0.77 (0.43–1.37)
1.14 (0.49–1.59)
-0.113 (0.060)
Qualifications
–
0.47** (0.32– 0.69)
0.82* (0.42– 0.90)
-0.131** (0.131)
Cannabis use Re-victimization
– –
1.24 (0.83–1.85) 3.14** (2.14–4.59)
0.91 (0.65–1.52) 1.78** (1.40–3.01)
0.225** (0.044) 0.391** (0.043)
Loneliness
–
–
3.69** (3.04–4.57)
2.22** (1.411–3.51)
1.63* (1.00–2.64)
1.32 (0.80–2.18)
0.232** (0.052)
CPA
5.54** (3.27–9.39)
3.79** (2.22–6.47)
2.41** (1.37–4.23)
0.436** (0.089)
CSA and CPA
5.55** (2.59–12.04)
2.74* (1.22–6.14)
1.73 (0.76–3.96)
0.577** (0.133)
GAD
Loneliness MAD
0.504** (0.113)
0.348** (0.791) -0.002** (0.000) 0.077** (0.015)
Phobia
Depression CSA
0.156** (0.032)
PTSD CSA
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Soc Psychiatry Psychiatr Epidemiol Table 2 continued Phase 1 OR (95 % CI)
Phase 2 OR (95 % CI)
Phase 3 OR (95 % CI)
Indirect effect b (S.E.)
Age
–
0.97** (0.96–0.98)
0.98** (0.97–0.98)
-0.004**(0.001)
Sex
–
0.78 (0.56–1.08)
0.94 (0.67–1.32)
0.128**(0.026)
Ethnicity Qualifications
– –
0.91 (0.52–1.60) 0.50** (0.35–0.72)
1.03 (0.59–1.81) 0.61* (0.42–0.90)
-0.093 (0.049) -0.107** (0.032)
Cannabis use
–
1.03 (0.70–1.51)
0.82 (0.54–1.22)
0.184** (0.036)
Re-victimization
–
3.31** (2.27–4.83)
2.28** (1.55–3.34)
0.320** (0.036)
Loneliness
–
–
2.94** (2.48–3.50)
CSA
2.68 (0.83–8.69)
1.60 (0.5–5.14)
1.25 (0.39–3.98)
0.291** (0.098)
CPA
4.44 (0.95–20.69)
2.55 (0.54–11.99)
1.31 (0.29–5.88)
0.546** (0.175)
CSA and CPA
19.55** (6.00–63.70)
7.00** (1.96–25.05)
3.81* (1.07–13.61)
Age
–
0.99 (0.97–1.00)
0.99 (0.97–1.02)
-0.005** (0.002)
Sex
–
0.57 (0.21–1.50)
0.72 (0.26–2.05)
-0.161** (0.051)
Ethnicity
–
0.71 (0.20–2.52)
0.69 (0.21–2.35)
-0.117 (0.068)
Qualifications
–
0.44 (0.15–1.30)
0.61 (0.19–1.98)
-0.134* (0.053)
Cannabis use
–
1.79 (0.69–4.67)
1.47 (0.52–4.17)
0.231** (0.072)
Re-victimization
–
6.22** (2.00–19.31)
4.02* (1.24–13.08)
0.401** (0.111)
Loneliness
–
–
3.87** (1.93–7.76)
Variable
Psychosis
0.722** (0.242)
CSA childhood sexual abuse endorsed only, CPA childhood physical abuse endorsed only, CSA and CPA both CPA and CSA endorsed, b beta coefficient, S.E. standard error ** p \ 0.01; * p \ 0.05
Table 3 Fit indices for the mediation model Model
Loglikelihood
# Free parameters
AIC
BIC
ssaBIC
Phase 1
-24,709
28
49,474
49,667
49,578
Phase 2
-24,439
64
49,006
49,447
49,244
Phase 3
-23,584
79
47,325
47,870
47,619
AIC Akaike information criterion, BIC Bayesian information criterion, ssaBIC sample-size-adjusted BIC
In phase 1, the three CA variables significantly predicted each psychiatric diagnosis, except in the case of psychosis where only the combined CSA and CPA variable had a statistically significant association. For each diagnosis, the effects were highest for the combined CSA and CPA variable, with ORs ranging from 3.01 for MAD to 19.55 for psychosis. The effects were generally higher for CPA compared to CSA, with ORs ranging from 1.74 for MAD to 6.70 for phobia. The introduction of the background variables in phase 2 resulted in an overall decrease in the ORs. Once these variables were introduced, the effects of CPA and combined CSA and CPA on MAD were no longer statistically significant. The biggest decrease in ORs was for psychosis (from 19.55 to 7.00). The smallest decrease in ORs was for MAD in the CSA group (from 1.97 to 1.43). In phase 3, adult loneliness was predicted by CSA (b = 0.25, SE = 0.05, p \ 0.01), CPA (b = 0.46,
SE = 0.08, p \ 0.01), combined CSA and CPA (b = 0.610, SE = 0.131, p \ 0.01), age (b = -0.004, SE = 0.001, p \ 0.01), sex (b = 0.135, SE = 0.03, p \ 0.01), qualifications (b = 0.11, SE = 0.03, p \ 0.01), lifetime cannabis use (b = 0.195, SE = 0.04, p \ 0.01) and re-victimization (b = 0.34, SE = 0.03, p \ 0.01). The loneliness variable significantly predicted each of the adult psychiatric diagnoses, with ORs ranging from 1.92 (95 % CI 1.745–2.11) for MAD to 3.87 (95 % CI 1.93–7.76) for psychosis. The products of the direct paths between the CA variables and the mediator variable, and the mediator variable and the psychiatric diagnoses variables are presented in Table 2. These indirect effects (via loneliness) for each of the CA variables on each psychiatric diagnosis were statistically significant. Also, the introduction of this mediator led to an overall reduction in the ORs for the direct effects between CA and the diagnosis variables. On the basis of these estimates, and the Chi square difference
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test which indicated that the introduction of the loneliness variable significantly improved the model, it was concluded that loneliness was a significant mediator between CA and the psychiatric disorders.
Discussion The present study aimed to (1) examine whether CA was significantly associated with adult loneliness and psychopathology, (2) examine whether cumulative CSA and CPA were associated with greater levels of psychopathology and loneliness compared to CSA or CPA alone, and (3) test whether loneliness mediated the relationship between CA and six adult psychiatric disorders. The CA variables significantly predicted all six of the adult psychiatric diagnoses and adult loneliness; therefore, the first hypothesis was supported. These findings were consistent with a large body of evidence that links CA with the development of psychopathology and loneliness in adulthood [8, 13, 14, 16, 38, 39, 66, 67]. An examination of the ORs indicated that the likelihood of meeting the diagnostic criteria of GAD, phobia, and psychosis was higher for those who reported both CSA and CPA. In cases of MAD, depression and PTSD, however, this pattern was not observed. As such, the second hypothesis was only partially supported. This finding appears to contradict previous research which suggests that exposure to multiple forms of CA is more detrimental to adult mental health than repeated exposure to one specific type [30, 31]. It must be noted, however, that the present study did not take the frequency and severity of CA into account. As such, it was not possible to make direct comparisons between multiple forms of CA and sustained single forms of CA. Further research, taking frequency and severity of CA into account, may be required to properly compare these forms of CA. The introduction of the loneliness mediator variable led to a reduction in the direct effects of CSA only and CPA only on six of the psychiatric diagnoses. For most of the diagnoses these effects became statistically non-significant, suggesting full mediation. The introduction of this variable saw a reduction in effects at the combined CSA and CPA level; however, the effects at this level remained statistically significant for most of the diagnoses, suggesting partial mediation. Overall, this provides broad support for the third hypothesis. These results are consistent with previous research which has found similar mediated effects [50, 52]. The present study expands upon this previous work by including a variety of adult psychiatric diagnoses, using a large general population sample of both males and females, and controlling for revictimization in adulthood.
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Limitations The above findings should be considered in light of the following limitations. First, as cross-sectional data were used, the temporal ordering of loneliness and psychiatric disorders cannot be unequivocally determined. However, research indicates that loneliness is relatively stable across the life span [48, 49], while the past year diagnoses reported in the APMS peaked at the age group 45–54 years for women and 25–54 years for men [54]. As such, it is likely the feelings of loneliness preceded these diagnoses. Further research employing a fully longitudinal design is required before firm causal inferences can be made (see Maxwell & Cole, [68]). Second, loneliness was measured by a single item. While this measure of loneliness has been used in previous epidemiological research [42], single item measures may have poorer validity and reliability compared to multi-item scales, resulting in attenuated statistical associations. Also, research has indicated that males tend to under-report loneliness when single item scales are used [69], although gender was included as a covariate in the present analysis to statistically control for this effect. Third, as the mean age was 51.12 years, the reliability of respondent’s reports of CA could be questioned. However, research indicates that retrospective recall is an acceptable method for measuring childhood trauma such as physical or sexual abuse as it is more likely to result in the underreporting of CA rather than over-reporting [70]. Fourth, the frequency and severity of CA, beyond the co-occurrence of CSA and CPA, was not assessed. This could have had a confounding effect on the results given that research suggests a dose–response relationship between CA and adult psychopathology [16, 18, 20–22]. Also, reports of CPA were restricted to abuse at the hands of parents or caregivers. This excludes physical abuse from other potential sources (e.g., peers) which has been shown to have a deleterious effect on adult mental health [71, 72]. Theoretical and practical implications The results of this study have both theoretical and clinical implications. Although this paper did not aim to explicitly test the ‘loneliness loop’ model proposed by Hawkley and Cacioppo [32], the present findings compliment this theoretical framework. This model suggests that feelings of loneliness may trigger hypervigilance regarding the social environment. This in turn produces cognitive biases and self-fulfilling prophecies which cause distress, and which may eventually lead to the development of psychiatric disorders [32]. Introducing CA to this framework builds upon this model; along with the direct effects of CA on the development of adult psychopathology, CA may also have an indirect effect on psychopathology through loneliness
Soc Psychiatry Psychiatr Epidemiol
Fig. 2 Graphical illustration of CA within the ‘loneliness loop’ framework proposed by Hawkley and Cacioppo (2010)
(Fig. 2). It is possible that CA precedes and leads to the initial feelings of loneliness. CA survivors may perceive the social world as more threatening than others, causing them to become more socially withdrawn and lonely. This in turn may lead to the cognitive biases and self-fulfilling prophecies that constitute the ‘loneliness loop’. This selfreinforcing loop may ultimately lead to the development of psychopathology. Further research using longitudinal data would be required to properly test this model. In relation to psychosis, the findings from this study fit within the social deafferentation framework. The social deafferentation hypothesis posits that prolonged social withdrawal may lead to the development of social cognition programmes which produce false social meaning in the form of hallucinations and/or delusions [45]. Recent research has taken this idea a step further, suggesting that subjective rather than objective social isolation may be influential in the development of psychosis [33]. Indeed, in an analysis of the British Psychiatric Morbidity Survey (BPMS; N = 8,580) Murphy and colleagues [33] found that avoidant personality traits mediated the relationship between childhood trauma and psychosis, while selfreported social contact did not. The findings from the present study corroborate the work of Murphy and colleagues [33] and suggest that subjective feelings of social isolation, in this case characterized by loneliness, may be influential in the development of psychosis. It is important to note that many societal and life events are associated with the development of loneliness, such as advancing age, widowhood, and low level of education [73]. The present study focussed on one particular antecedent of loneliness; CA. Further research could be required to establish whether such trauma-based loneliness represents a greater threat to adult mental health than other forms of loneliness. The findings from this study highlight the importance of adequate social relationships for individuals presenting
with mental health problems. At the assessment level, clinicians should be encouraged to consider the individual’s perceived level of social isolation, rather than their objective level of social isolation. An accurate assessment of social needs could lead to the development of social conditioning interventions aimed at reducing feelings of loneliness (e.g., access to work, education, recreation, social skills training, and improved access to meaningful activities). Such interventions could lead to more meaningful social relationships and reduced feelings of loneliness. This in turn may lead to positive outcomes across a variety of mental health problems.
Conclusion The present study examined whether loneliness mediated the relationship between CA and adult psychopathology in a large general population sample. Results indicated that loneliness was a significant mediator in the relationship between CA and six adult psychiatric diagnoses. Although limited by the cross-sectional nature of the data, this study highlights the theoretical and clinical importance of loneliness to the development of psychopathology. Further research using longitudinal designs is recommended.
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