SHORT COMMUNICATION
Post-traumatic Stress Disorder Symptoms Mediate the Relationship Between Trauma Exposure and Smoking Status in College Students Crystal A. Gabert-Quillen1‡, Arielle Selya2 & Douglas L. Delahanty1*† 1
Department of Psychology, Kent State University, Kent, OH, USA Department of Psychology, Wesleyan University, Middletown, CT, USA
2
Abstract The present study examined the relationship between trauma exposure and smoking status and the extent to which post-traumatic stress disorder symptoms mediated this relationship in a sample of 329 college students who experienced a prior traumatic event. Participants experienced an average of 2.2 prior traumas, and approximately 15% (n = 49) were smokers. Bootstrapping analyses revealed that after controlling for age, gender and time since trauma, post-traumatic stress disorder symptoms served as a pathway through which trauma exposure increased the risk of smoking [BC 95% CI (0.02, 0.18)]. Results appeared to be due largely to the influence of hyperarousal symptoms [BC 95% CI (0.05, 0.22)]. Comprehensive interventions for undergraduate smokers may be improved by attending to the impact of prior trauma and mental health needs. Copyright © 2014 John Wiley & Sons, Ltd. Received 12 April 2013; Revised 17 June 2013; Accepted 19 September 2013 Keywords smoking; college students; PTSD symptoms; trauma; hyperarousal *Correspondence Douglas L. Delahanty, Department of Psychology, 118 Kent Hall, Kent State University, Kent, OH 44242 USA. † Email: [email protected] ‡ Present Address: Wesleyan University, Middletown, CT, USA. Published online 14 January 2014 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/smi.2543
Prior research has demonstrated a positive relationship between extent of trauma exposure (i.e. number of prior traumas) and smoking (Roberts, Fuemmeler, McClernon, & Beckham, 2008; Hapke et al., 2005). Reviews and empirical studies have suggested that post-traumatic stress disorder (PTSD) is more strongly related to smoking behaviour than trauma exposure (Breslau, Davis, & Schultz, 2003; Feldner, Babson, & Zvolensky, 2007; Fu et al., 2007). However, some studies have shown that trauma exposure increases the risk of smoking independent of PTSD (Hapke et al., 2005). Therefore, it is unclear whether PTSD may explain the relationship between trauma exposure and smoking. Further, this relationship has not been well-established in specific populations such as college students. Trauma history prevalence rates for college students (56–84%; Smyth, Hockenmeyer, Heron, Wonderlich, & Pennebaker, 2008) are comparable with, and often higher than, prevalence rates in adults (55–69%; Kessler, Sonnega, Bromet, Hughes, & Nelson, 1995), with undergraduates often experiencing more than one traumatic event in their lifetime (55–63%; Frazier et al., 2009; Smyth et al., 2008). Additionally, in 78
undergraduates, exposure to more than one trauma increases risk for PTSD over exposure to one trauma (Frazier et al., 2009). Although the prevalence rates of adult smokers with trauma exposure/PTSD have been reported (Lasser et al., 2000), the relationship between smoking and trauma exposure/PTSD in college student is unclear. College students (aged 18–25 years) report the highest current smoking rates (41%) compared with youth (aged 12–17 years; 13%) and adults (aged 26 years or older, 25%; Office of Applied Studies, 2011) in the United States. PTSD symptoms have been associated with a greater number of cigarettes smoked in undergraduates (Flood, McDevitt-Murphy, Weathers, Eakin, & Benson, 2009), and college freshmen with a PTSD diagnosis had higher rates of smoking than freshmen without a PTSD diagnosis (Read et al., 2013). However, these studies have not separately examined the impact of trauma exposure versus PTSD symptoms. In addition, results have been mixed as to whether specific PTSD symptom clusters (i.e. reexperiencing, avoidance/numbing and hyperarousal) are differentially related to smoking behaviour (Beckham et al., Stress Health 31: 78–82 (2015) © 2014 John Wiley & Sons, Ltd.
C. A. Gabert-Quillen, A. Selya and D. L. Delahanty
2005; Greenberg et al., 2012; Thorndike, Wernicke, Pearlman, & Haaga, 2006; Weaver & Etzel, 2003). As an understanding of specific PTSD symptoms associated with smoking in college students would better inform specific intervention efforts, the current study sought to examine the extent to which PTSD symptoms and symptom clusters mediated the relationship between number of prior trauma exposures and smoking behaviour in college students. It was hypothesized that PTSD symptoms would mediate the relationship between number of prior traumatic experiences and smoking status. Because of the lack of prior findings concerning specific symptoms of PTSD and smoking, we did not make directional hypotheses, and consider these analyses exploratory.
Method Participants Participants consisted of 329 college students from a large Midwestern university who reported at least one prior traumatic experience. Of these, 17.3% (n = 57) were male, and 82.7% (n = 272) were female. Approximately 88% (n = 287) reported that they were either in their first or second year of college. Students ranged in age from 18 to 28 years, with a mean of 19 years [standard deviation (SD) = 1.8]. Procedure The University’s human subjects review board committee approved the following procedures. Participants who were enrolled in Psychology classes were invited to participate in an online survey. After consenting, students were instructed to complete questionnaires pertaining to their trauma exposure, PTSD symptoms and smoking status from a private location. Participants received course credit for completing these measures. Measures Trauma exposure and post-traumatic stress disorder symptoms Trauma exposure and PTSD symptoms were assessed with the Post-traumatic Stress Diagnostic Scale (Foa, 1995). This 48-item measure includes a trauma exposure checklist and a symptom severity portion that participants are asked to complete with reference to the most stressful trauma they have experienced. Participants had to endorse both criteria A1 (experience or witness an event that involved actual or threatened death or serious injury) and A2 (experience fear, helplessness or horror) to be eligible to participate. Symptom severity within the past month was rated on a scale from 0 (not at all bothered by symptom) to 3 (bothered more than five times a week). Symptom clusters (i.e. reexperiencing, avoidance/numbing, hyperarousal) were assessed with a continuous score. A cutoff score of 26 identified undergraduates with a ‘probable’ PTSD diagnosis (Adkins, Weathers, McDevittStress Health 31: 78–82 (2015) © 2014 John Wiley & Sons, Ltd.
Trauma Exposure and Smoking
Murphy, & Daniels, 2008). The Post-traumatic Stress Diagnostic Scale is considered to be a valid and reliable measure of PTSD (McCarthy, 2008). Internal consistency for the present study was good (α = 0.92). Smoking status Participants were asked to reply ‘yes’ or ‘no’ to the following question: ‘Do you currently smoke cigarettes?’ Data analysis In order to test for possible control variables, Pearson product-moment and Spearman’s rho correlations were conducted between continuous and ordinal variables, respectively. One-way analysis of variances were conducted between continuous and categorical variables, and chi-square analyses were conducted between categorical variables. Following suggestions by Preacher and Hayes (2004), the current study used a bootstrapping approach to estimate the total and indirect effect. This method generates 5000 bootstrap samples to estimate the indirect effect (i.e. the product of the coefficients of (1) trauma exposure—>PTSD/hyperarousal symptoms and (2) PTSD/hyperarousal symptoms—>smoking status). For mediation to be supported, the mediator (i.e. PTSD/ hyperarousal symptoms) must be associated with both the predictor (i.e. trauma exposure) and outcome (i.e. smoking status) variable after controlling for covariates. Because this indirect effect represents the difference between the total effect and the direct effect, a value significantly different from 0 (based on the 95% biascorrected confidence interval of the estimate) indicates the presence of mediation. An SPSS (IBM Corp., IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY) macro developed for testing mediation with bootstrapping was utilized (Preacher & Hayes, 2008).
Results Preliminary analyses The number of prior traumas experienced per participant ranged from 1 to 10 (M = 2.2, SD = 1.4). With respect to the worst event experienced, 27% endorsed an accident, 22.7% experienced or were exposed to a life-threatening illness, 11.4% were physically assaulted, 12% were sexually assaulted, 8.9% endorsed the death of a family member or friend, 8.3% of the sample endorsed an ‘other’ event (e.g. emotional abuse), 7.1% were involved in a natural disaster and 2.7% experienced combat, imprisonment or torture. PTSD symptom scores ranged from 0 to 44 (M = 10.5, SD = 9.8). On the basis of the previously mentioned cutoff score, 8.7% (n = 29) of the sample met criteria for a probable PTSD diagnosis. Although 15% of the entire sample labelled themselves as smokers, 27.6% of those with a probable PTSD diagnosis reported being smokers. Bivariate correlations revealed that age and time since trauma should be included as covariates for the mediation model. Older students (r = 0.17, p = 0.002) 79
Trauma Exposure and Smoking
C. A. Gabert-Quillen, A. Selya and D. L. Delahanty
symptoms significantly mediated the relationship between number of trauma exposures and smoking status [Figure 1b; BC 95% CI (0.05, 0.22)]. None of the other symptom clusters were significant mediators of the relationship between number of traumatic exposures and smoking status. Because of the cross-sectional nature of this study, it is impossible to determine the temporal relationship between number of traumatic exposures, PTSD/ hyperarousal symptoms and smoking. Therefore, on
and those with more PTSD symptoms (r = 0.29, p < 0.001) reported a greater number of prior traumas (see Supporting information). Those with greater PTSD symptoms were older (r = 0.13, p = 0.02) and had more recent traumas (r = 0.11, p = 0.05). One-way analysis of variances revealed that individuals who smoked were more likely to be older [F (1, 330) = 8.86, p = 0.003], to report a greater number of prior traumas [F (1, 330) = 11.24, p = 0.001], to have more avoidance/numbing and hyperarousal symptoms [F (1, 329) = 5.89, p = 0.02; F (1, 329) = 24.38, p < 0.001, respectively] and to have greater overall PTSD symptoms [F (1, 330) = 11.46, p = 0.001]. Gender was not significantly related to the study variables but was marginally related to smoking status (p = 0.06); therefore, it was used as a control variable in the mediation analyses.
a
Regression analyses Mediation analyses using a bootstrap approach (Table I) were conducted controlling for several variables (i.e. age, gender and time since trauma). Number of traumatic exposures was associated both with an increased likelihood of smoking (B = 0.26, p = 0.006) and with more PTSD symptoms (B = 2.01, p < 0.001). Participants with greater PTSD symptoms were significantly more likely to be smokers (B = 0.04, p = 0.01). Finally, the indirect effect of number of traumatic exposures and smoking status through PTSD symptoms was significant (B = 0.18, p = 0.08). The overall bootstrap analysis of the indirect effect was significant, indicating that PTSD symptoms served as a mediator between number of traumatic exposures and smoking status [Figure 1a; BC 95% CI (0.02, 0.18)]. Similar analyses were conducted to determine whether PTSD symptom clusters differentially mediated the relationship between number of traumatic exposures and smoking. The symptom clusters of reexperiencing, avoidance/numbing and hyperarousal symptoms were examined separately as possible mediators. A bootstrap analysis revealed that hyperarousal
b
Figure 1. (a) Results of the mediation model examining trauma exposure, post-traumatic stress disorder (PTSD) symptoms and smoking status in college students. B in parentheses: the direct path after controlling for PTSD symptoms. (b) Results of the mediation model examining trauma exposure, hyperarousal symptoms and smoking status in college students. B in parentheses: the direct effect after controlling for hyperarousal symptoms.
Table I. Path coefficients and standard errors examining the significance of the indirect effect (post-traumatic stress disorder/hyperarousal symptoms mediates the relationship between trauma exposure and smoking status) PTSD symptoms Path and variables Path A:Trauma exposure ➔ PTSD symptoms Path B:PTSD symptoms ➔ smoking status Path C (total effect):Trauma exposure ➔ smoking status Path C′ (direct effect):Trauma exposure ➔ smoking status
B
SE
t/Z
2.01 0.04 0.26 0.18
0.36 0.02 0.09 0.10
5.62*** 2.54* 2.74** 1.77†
Hyperarousal symptoms
BC 95% CI
B
SE
t/Z
BC 95% CI
[0.02, 0.18]
0.67 0.18 0.26 0.15
0.13 0.04 0.09 0.10
4.95*** 3.93*** 2.74** 1.42
[0.05, 0.22]
All path coefficients were derived from 5000 bootstrap samples. BC 95% CI not including zero represents significance of model (bolded). Models were adjusted for age, gender and time since trauma. t-score was used for Path A; Z-score was used for other paths. N = 329. PTSD, post-traumatic stress disorder; BC, bias-corrected; CI, confidence interval; SE, standard error. † p < 0.10. *p < 0.05. **p < 0.01. ***p < 0.001.
80
Stress Health 31: 78–82 (2015) © 2014 John Wiley & Sons, Ltd.
C. A. Gabert-Quillen, A. Selya and D. L. Delahanty
the basis of prior research demonstrating that smoking may help to maintain PTSD symptoms (van der Velden, Kleber, & Koenen, 2008), we ran an alternative model to assess whether smoking status might mediate the relationship between number of traumatic exposures and PTSD/hyperarousal symptoms. The mediation findings were significant for both PTSD symptoms and hyperarousal symptoms. However, comparison of effect sizes (ESs) (Preacher & Kelley, 2011) for the original model (PTSD/ hyperarousal symptoms mediating the relationship between extent of trauma exposure and smoking status) and the new model (smoking status mediates the relationship between extent of prior trauma exposure and PTSD/hyperarousal symptoms) suggest that the original model was the stronger model for both total PTSD symptoms (ES = 0.45 versus 0.08, respectively) and hyperarousal symptoms (ES = 0.80 versus 0.16, respectively).
Discussion The results of the present study add to the existing body of literature demonstrating a link between trauma exposure/PTSD and increased smoking rates (Feldner et al., 2007; Fu et al., 2007) and extend prior findings by demonstrating that PTSD symptoms served as a mechanism for the relationship between number of traumatic exposures and smoking status in college students after controlling for age, gender and time since trauma. Further, results seemed to be primarily due to the significant mediating effect of hyperarousal symptoms. Hyperarousal symptoms have been previously shown to predict smoking and nicotine dependence among participants (Beckham et al., 2005; Feldner et al., 2007; Greenberg et al., 2012; Thorndike et al., 2006). However, to our knowledge, this is the first study to find that hyperarousal symptoms mediated the relationship between number of traumatic exposures and smoking status. Hyperarousal symptoms have been found to play a large role in the maintenance of PTSD symptoms after a traumatic event (Schell, Marshall, & Jaycox, 2004) and to lead to poor health outcomes (Perez, Abrams, Lopez-Martinez, & Asmundson, 2012). Arousal symptoms may also contribute to the role substances play in coping with PTSD symptoms (Jacobsen, Southwick, & Kosten, 2001). Individuals with PTSD may smoke to decrease their hyperarousal symptoms (e.g. difficulty concentrating, hypervigilance and irritability), contributing to the relationship observed in the present study. However, given the exploratory nature of REFERENCES
Trauma Exposure and Smoking
these findings, future work is necessary to replicate these findings and to determine the role that hyperarousal symptoms have in contributing to an increased risk for smoking behaviour. The present findings may help to inform smoking cessation efforts. In a recent smoking cessation study, individuals with PTSD had worse cravings and more severe withdrawal symptoms compared with those without PTSD (Dedert et al., 2012). In addition, cigarette deprivation was shown to increase anxiety in individuals with PTSD (Vujanovic, Marshall-Berenz, Beckham, Bernstein, & Zvolensky, 2010). Results from this study may help to shed light on specific PTSD symptoms that may contribute to difficulties in smoking cessation. As withdrawal symptoms are similar to hyperarousal symptoms, this may lead to worsening of PTSD symptoms and a subsequent need to keep smoking (Jacobsen et al., 2001). There are a few limitations to this study. The crosssectional nature limits the ability to examine how the relationship between PTSD symptoms and smoking status may change over time. The sample was also predominantly female, limiting confidence for generalizing these findings to male college students. Additionally, reports of trauma exposure and PTSD symptoms were assessed via questionnaire; however, research has suggested that questionnaire assessment of post-traumatic symptoms may lead to more accurate symptom reporting than clinical assessment (Schnurr, Friedman, & Bernardy, 2002). We also used a categorical measure of smoking status. Future studies should use more comprehensive measures, especially with respect to the assessment of smoking behaviours (e.g. smoking frequency and quantity). Despite these limitations, the current study indicated that the extent of prior trauma exposure impacts the mental health of college students and their health behaviours and that attention to PTSD symptoms may increase the efficacy of smoking cessation interventions. Attention should also be focused, in particular, on the role of hyperarousal symptoms in contributing to smoking behaviours. Further understanding of these relationships will help to develop more targeted interventions for college student smokers with a trauma exposure.
Acknowledgments The authors wish to thank Bryce Hruska for his advice on revisions of this manuscript. Preparation of this manuscript was supported, in part, by the National Institute of Mental Health (R34 MH073014).
disorder in college students with mixed civilian trauma exposure. Journal of Anxiety Disorder, 22, 1393–1402.
preliminary study. Experimental and Clinical Psychopharmacology, 13(3), 219–228.
Beckham, J. C., Feldman, M. E., Vrana, S. R., Mozley, S.
Breslau, N., Davis, G. C., & Schultz, L. R. (2003).
Adkins, J. W., Weathers, F. W., McDevitt-Murphy, M.,
L., Erkanli, A., Clancy, C. P., & Rose, J. E. (2005). Im-
Posttraumatic stress disorder and the incidence of nicotine, al-
& Daniels, J. B. (2008). Psychometric properties of
mediate antecedents of cigarette smoking in smokers
cohol, and other drug disorder in persons who have experi-
seven self-report measures of posttraumatic stress
with and without posttraumatic stress disorder: A
enced trauma. Archives of General Psychiatry, 60(3), 289–294.
Stress Health 31: 78–82 (2015) © 2014 John Wiley & Sons, Ltd.
81
Trauma Exposure and Smoking Dedert, E. A., Calhoun, P. S., Harper, L. A., Dutton, C. E., McClerno, H. J., & Beckham, J. C. (2012).
C. A. Gabert-Quillen, A. Selya and D. L. Delahanty literature. American Journal of Psychiatry, 158 (8),
exposure and smoking in a population-based sample of young adults. Journal of Adolescent Health, 42(3),
1184–1190
Smoking withdrawal in smokers with and without
Kessler, R. C., Sonnega, A., Bromet, E., Hughes, M., &
posttraumatic stress disorder. Nicotine and Tobacco
Nelson, C. B. (1995). Posttraumatic stress disorder
Schell, T. L., Marshall, G. N., & Jaycox, L. H. (2004). All
Research, 14(3), 372–376.
in the National Comorbidity Survey. Archives of Gen-
symptoms are not created equal: The prominent role
eral Psychiatry, 52(12), 1048–1060.
of
Feldner, M. T., Babson, K. A., & Zvolensky, M. J. (2007). Smoking, traumatic event exposure, and
Lasser, K., Boyd, J. W., Woolhandler, S., Himmelstein,
post-traumatic stress: A critical review of the empiri-
D. U., McCormick, D., & Bor, D. H. (2000). Smoking
cal literature. Clinical Psychology Review, 27, 14–45.
and mental illness: A population-based prevalence
Flood, A. M., McDevitt-Murphy, M. E., Weathers, F. W., Eakin, D. E., & Benson, T. A. (2009). Substance use behaviors as a mediator between posttraumatic
266–274.
hyperarousal
in
the
natural
course
of
posttraumatic psychological distress. Journal of Abnormal Psychology, 113(2), 189–197. Schnurr, P. P., Friedman, M. J., & Bernardy, N. C. (2002). Research on posttraumatic stress disorder:
study. JAMA, 284(20), 2606–2610. McCarthy, S. (2008). Post-Traumatic Stress Diagnostic Scale (PDS). Occupational Medicine, 58, 379.
Epidemiology, pathophysiology, and assessment. Journal
of
Clinical
Psychology,
58,
877–889.
stress disorder and physical health in trauma-
Office of Applied Studies. (2011). Results from the 2010
exposed college students. Journal of Behavioral Medi-
National Survey on Drug Use and Health: Summary
Smyth, J. M., Hockenmeyer, J. R., Heron, K. E.,
cine, 32(3), 234–243.
of National Findings. Rockville, MD: Substance
Wonderlich, S. A., & Pennebaker, J. W. (2008). Prev-
doi:10.1002/jclp.10064
Abuse and Mental Health Services Administration.
alence, type, disclosure, and severity of adverse life
ual. Minneapolis, MN: National Computer Systems.
Perez, L. G., Abrams, M. P., Lopez-Martinez, A. E., &
events in college students. Journal of American College
Frazier, P., Anders, S., Perera, S., Tomich, P., Tennen,
Asmundson, G. J. (2012). Trauma exposure and
H., Park, C., & Tashiro, T. (2009). Traumatic events
health: The role of depression and hyperarousal
Thorndike, F. P., Wernicke, R., Pearlman, M. Y., &
among undergraduate students: Prevalence and asso-
symptoms. Journal of Traumatic Stress, 25(6),
Haaga, D. A. F. (2006). Nicotine dependence, PTSD
ciated symptoms. Journal of Counseling Psychology,
641–648.
symptoms, and depression proneness among male
Foa, E. B. (1995). Posttraumatic Diagnostic Scale Man-
56(3), 450–460.
Preacher, K. J., & Hayes, A. F. (2004). SPSS and SAS
Fu, S. S., McFall, M., Saxon, A. J., Beckham, J. C.,
procedures for estimating indirect effects in simple
Carmody, T. P., Baker, D. G., & Joseph, A. M.
mediation models. Behavior Research Methods, Instru-
(2007). Post-traumatic stress disorder and smoking: A systematic review. Nicotine and Tobacco Research, 9(11), 1071–1084. Greenberg, J. B., Ameringer, K. J., Trujillo, M. A., Sun, P., Sussman, S., Brightman, M.,…Leventhal, A. M.
Health, 57, 69–76.
and female smokers. Addictive Behaviors, 31(2), 223–231. van der Velden, P. G., Kleber, R. J., & Koenen, K. C. (2008). Smoking predicts posttraumatic stress symp-
ments, and Computers, 36(4), 717–731. Preacher, K. J., & Hayes, A. F. (2008). Asymptotic and
toms among rescue workers: A prospective study of
resampling strategies for assessing and comparing in-
ambulance personnel involved in the Enschede
direct effects in multiple mediator models. Behavior
Fireworks Disaster. Drug and Alcohol Dependence, 94 (1-3), 267–271.
Research Methods, 40(3), 879–891.
(2012). Associations between posttraumatic stress
Preacher, K. J., & Kelley, K. (2011). Effect size measures
Vujanovic, A. A., Marshall-Berenz, E. C., Beckham,
disorder symptom clusters and cigarette smoking.
for mediation models: Quantitative strategies for
J. C., Bernstein, A., & Zvolensky, M. J. (2010).
Psychology of Addictive Behaviors, 26(1), 89–98.
communicating
Posttraumatic
Hapke, U., Schumann, A., Rumpf, H. J., John, U., Konerding,
indirect
effects.
Psychological
deprivation
Methods, 16(2), 93–115.
stress in
the
symptoms prediction
and
cigarette
of
anxious
U., & Meyer, C. (2005). Association of smoking and nico-
Read, J. P., Wardell, J. D., Vermont, L. N., Colder, C. R.,
responding among trauma-exposed smokers: A
tine dependence with trauma and posttraumatic stress dis-
Ouimette, P., & White, J. (2013). Transition and
laboratory test. Nicotine & Tobacco Research, 12
order in a general population sample. Journal of Nervous
change: Prospective effects of posttraumatic stress
and Mental Disease, 193(12), 843–846.
on smoking trajectories in the first year of college.
Jacobsen, L. K., Southwick, S. M., & Kosten, T. R.
(11), 1080–1088. Weaver, T. L., & Etzel, J. C. (2003). Smoking patterns, symptoms of PTSD and depression: Preliminary
Health Psychology, 32(7), 757–767.
(2001). Substance use disorders in patients with
Roberts, M. E., Fuemmeler, B. F., McClernon, F. J., &
posttraumatic stress disorder: A review of the
Beckham, J. C. (2008). Association between trauma
findings from a sample of severely battered women. Addictive Behaviors, 28(9), 1665–167.
Supporting information Additional supporting information may be found in the online version of this article at the publisher’s web site.
82
Stress Health 31: 78–82 (2015) © 2014 John Wiley & Sons, Ltd.
Copyright of Stress & Health: Journal of the International Society for the Investigation of Stress is the property of John Wiley & Sons, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
Post-traumatic Stress Disorder Symptoms Mediate the Relationship Between Trauma Exposure and Smoking Status in College Students Crystal A. Gabert-Quillen1‡, Arielle Selya2 & Douglas L. Delahanty1*† 1
Department of Psychology, Kent State University, Kent, OH, USA Department of Psychology, Wesleyan University, Middletown, CT, USA
2
Abstract The present study examined the relationship between trauma exposure and smoking status and the extent to which post-traumatic stress disorder symptoms mediated this relationship in a sample of 329 college students who experienced a prior traumatic event. Participants experienced an average of 2.2 prior traumas, and approximately 15% (n = 49) were smokers. Bootstrapping analyses revealed that after controlling for age, gender and time since trauma, post-traumatic stress disorder symptoms served as a pathway through which trauma exposure increased the risk of smoking [BC 95% CI (0.02, 0.18)]. Results appeared to be due largely to the influence of hyperarousal symptoms [BC 95% CI (0.05, 0.22)]. Comprehensive interventions for undergraduate smokers may be improved by attending to the impact of prior trauma and mental health needs. Copyright © 2014 John Wiley & Sons, Ltd. Received 12 April 2013; Revised 17 June 2013; Accepted 19 September 2013 Keywords smoking; college students; PTSD symptoms; trauma; hyperarousal *Correspondence Douglas L. Delahanty, Department of Psychology, 118 Kent Hall, Kent State University, Kent, OH 44242 USA. † Email: [email protected] ‡ Present Address: Wesleyan University, Middletown, CT, USA. Published online 14 January 2014 in Wiley Online Library (wileyonlinelibrary.com) DOI: 10.1002/smi.2543
Prior research has demonstrated a positive relationship between extent of trauma exposure (i.e. number of prior traumas) and smoking (Roberts, Fuemmeler, McClernon, & Beckham, 2008; Hapke et al., 2005). Reviews and empirical studies have suggested that post-traumatic stress disorder (PTSD) is more strongly related to smoking behaviour than trauma exposure (Breslau, Davis, & Schultz, 2003; Feldner, Babson, & Zvolensky, 2007; Fu et al., 2007). However, some studies have shown that trauma exposure increases the risk of smoking independent of PTSD (Hapke et al., 2005). Therefore, it is unclear whether PTSD may explain the relationship between trauma exposure and smoking. Further, this relationship has not been well-established in specific populations such as college students. Trauma history prevalence rates for college students (56–84%; Smyth, Hockenmeyer, Heron, Wonderlich, & Pennebaker, 2008) are comparable with, and often higher than, prevalence rates in adults (55–69%; Kessler, Sonnega, Bromet, Hughes, & Nelson, 1995), with undergraduates often experiencing more than one traumatic event in their lifetime (55–63%; Frazier et al., 2009; Smyth et al., 2008). Additionally, in 78
undergraduates, exposure to more than one trauma increases risk for PTSD over exposure to one trauma (Frazier et al., 2009). Although the prevalence rates of adult smokers with trauma exposure/PTSD have been reported (Lasser et al., 2000), the relationship between smoking and trauma exposure/PTSD in college student is unclear. College students (aged 18–25 years) report the highest current smoking rates (41%) compared with youth (aged 12–17 years; 13%) and adults (aged 26 years or older, 25%; Office of Applied Studies, 2011) in the United States. PTSD symptoms have been associated with a greater number of cigarettes smoked in undergraduates (Flood, McDevitt-Murphy, Weathers, Eakin, & Benson, 2009), and college freshmen with a PTSD diagnosis had higher rates of smoking than freshmen without a PTSD diagnosis (Read et al., 2013). However, these studies have not separately examined the impact of trauma exposure versus PTSD symptoms. In addition, results have been mixed as to whether specific PTSD symptom clusters (i.e. reexperiencing, avoidance/numbing and hyperarousal) are differentially related to smoking behaviour (Beckham et al., Stress Health 31: 78–82 (2015) © 2014 John Wiley & Sons, Ltd.
C. A. Gabert-Quillen, A. Selya and D. L. Delahanty
2005; Greenberg et al., 2012; Thorndike, Wernicke, Pearlman, & Haaga, 2006; Weaver & Etzel, 2003). As an understanding of specific PTSD symptoms associated with smoking in college students would better inform specific intervention efforts, the current study sought to examine the extent to which PTSD symptoms and symptom clusters mediated the relationship between number of prior trauma exposures and smoking behaviour in college students. It was hypothesized that PTSD symptoms would mediate the relationship between number of prior traumatic experiences and smoking status. Because of the lack of prior findings concerning specific symptoms of PTSD and smoking, we did not make directional hypotheses, and consider these analyses exploratory.
Method Participants Participants consisted of 329 college students from a large Midwestern university who reported at least one prior traumatic experience. Of these, 17.3% (n = 57) were male, and 82.7% (n = 272) were female. Approximately 88% (n = 287) reported that they were either in their first or second year of college. Students ranged in age from 18 to 28 years, with a mean of 19 years [standard deviation (SD) = 1.8]. Procedure The University’s human subjects review board committee approved the following procedures. Participants who were enrolled in Psychology classes were invited to participate in an online survey. After consenting, students were instructed to complete questionnaires pertaining to their trauma exposure, PTSD symptoms and smoking status from a private location. Participants received course credit for completing these measures. Measures Trauma exposure and post-traumatic stress disorder symptoms Trauma exposure and PTSD symptoms were assessed with the Post-traumatic Stress Diagnostic Scale (Foa, 1995). This 48-item measure includes a trauma exposure checklist and a symptom severity portion that participants are asked to complete with reference to the most stressful trauma they have experienced. Participants had to endorse both criteria A1 (experience or witness an event that involved actual or threatened death or serious injury) and A2 (experience fear, helplessness or horror) to be eligible to participate. Symptom severity within the past month was rated on a scale from 0 (not at all bothered by symptom) to 3 (bothered more than five times a week). Symptom clusters (i.e. reexperiencing, avoidance/numbing, hyperarousal) were assessed with a continuous score. A cutoff score of 26 identified undergraduates with a ‘probable’ PTSD diagnosis (Adkins, Weathers, McDevittStress Health 31: 78–82 (2015) © 2014 John Wiley & Sons, Ltd.
Trauma Exposure and Smoking
Murphy, & Daniels, 2008). The Post-traumatic Stress Diagnostic Scale is considered to be a valid and reliable measure of PTSD (McCarthy, 2008). Internal consistency for the present study was good (α = 0.92). Smoking status Participants were asked to reply ‘yes’ or ‘no’ to the following question: ‘Do you currently smoke cigarettes?’ Data analysis In order to test for possible control variables, Pearson product-moment and Spearman’s rho correlations were conducted between continuous and ordinal variables, respectively. One-way analysis of variances were conducted between continuous and categorical variables, and chi-square analyses were conducted between categorical variables. Following suggestions by Preacher and Hayes (2004), the current study used a bootstrapping approach to estimate the total and indirect effect. This method generates 5000 bootstrap samples to estimate the indirect effect (i.e. the product of the coefficients of (1) trauma exposure—>PTSD/hyperarousal symptoms and (2) PTSD/hyperarousal symptoms—>smoking status). For mediation to be supported, the mediator (i.e. PTSD/ hyperarousal symptoms) must be associated with both the predictor (i.e. trauma exposure) and outcome (i.e. smoking status) variable after controlling for covariates. Because this indirect effect represents the difference between the total effect and the direct effect, a value significantly different from 0 (based on the 95% biascorrected confidence interval of the estimate) indicates the presence of mediation. An SPSS (IBM Corp., IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY) macro developed for testing mediation with bootstrapping was utilized (Preacher & Hayes, 2008).
Results Preliminary analyses The number of prior traumas experienced per participant ranged from 1 to 10 (M = 2.2, SD = 1.4). With respect to the worst event experienced, 27% endorsed an accident, 22.7% experienced or were exposed to a life-threatening illness, 11.4% were physically assaulted, 12% were sexually assaulted, 8.9% endorsed the death of a family member or friend, 8.3% of the sample endorsed an ‘other’ event (e.g. emotional abuse), 7.1% were involved in a natural disaster and 2.7% experienced combat, imprisonment or torture. PTSD symptom scores ranged from 0 to 44 (M = 10.5, SD = 9.8). On the basis of the previously mentioned cutoff score, 8.7% (n = 29) of the sample met criteria for a probable PTSD diagnosis. Although 15% of the entire sample labelled themselves as smokers, 27.6% of those with a probable PTSD diagnosis reported being smokers. Bivariate correlations revealed that age and time since trauma should be included as covariates for the mediation model. Older students (r = 0.17, p = 0.002) 79
Trauma Exposure and Smoking
C. A. Gabert-Quillen, A. Selya and D. L. Delahanty
symptoms significantly mediated the relationship between number of trauma exposures and smoking status [Figure 1b; BC 95% CI (0.05, 0.22)]. None of the other symptom clusters were significant mediators of the relationship between number of traumatic exposures and smoking status. Because of the cross-sectional nature of this study, it is impossible to determine the temporal relationship between number of traumatic exposures, PTSD/ hyperarousal symptoms and smoking. Therefore, on
and those with more PTSD symptoms (r = 0.29, p < 0.001) reported a greater number of prior traumas (see Supporting information). Those with greater PTSD symptoms were older (r = 0.13, p = 0.02) and had more recent traumas (r = 0.11, p = 0.05). One-way analysis of variances revealed that individuals who smoked were more likely to be older [F (1, 330) = 8.86, p = 0.003], to report a greater number of prior traumas [F (1, 330) = 11.24, p = 0.001], to have more avoidance/numbing and hyperarousal symptoms [F (1, 329) = 5.89, p = 0.02; F (1, 329) = 24.38, p < 0.001, respectively] and to have greater overall PTSD symptoms [F (1, 330) = 11.46, p = 0.001]. Gender was not significantly related to the study variables but was marginally related to smoking status (p = 0.06); therefore, it was used as a control variable in the mediation analyses.
a
Regression analyses Mediation analyses using a bootstrap approach (Table I) were conducted controlling for several variables (i.e. age, gender and time since trauma). Number of traumatic exposures was associated both with an increased likelihood of smoking (B = 0.26, p = 0.006) and with more PTSD symptoms (B = 2.01, p < 0.001). Participants with greater PTSD symptoms were significantly more likely to be smokers (B = 0.04, p = 0.01). Finally, the indirect effect of number of traumatic exposures and smoking status through PTSD symptoms was significant (B = 0.18, p = 0.08). The overall bootstrap analysis of the indirect effect was significant, indicating that PTSD symptoms served as a mediator between number of traumatic exposures and smoking status [Figure 1a; BC 95% CI (0.02, 0.18)]. Similar analyses were conducted to determine whether PTSD symptom clusters differentially mediated the relationship between number of traumatic exposures and smoking. The symptom clusters of reexperiencing, avoidance/numbing and hyperarousal symptoms were examined separately as possible mediators. A bootstrap analysis revealed that hyperarousal
b
Figure 1. (a) Results of the mediation model examining trauma exposure, post-traumatic stress disorder (PTSD) symptoms and smoking status in college students. B in parentheses: the direct path after controlling for PTSD symptoms. (b) Results of the mediation model examining trauma exposure, hyperarousal symptoms and smoking status in college students. B in parentheses: the direct effect after controlling for hyperarousal symptoms.
Table I. Path coefficients and standard errors examining the significance of the indirect effect (post-traumatic stress disorder/hyperarousal symptoms mediates the relationship between trauma exposure and smoking status) PTSD symptoms Path and variables Path A:Trauma exposure ➔ PTSD symptoms Path B:PTSD symptoms ➔ smoking status Path C (total effect):Trauma exposure ➔ smoking status Path C′ (direct effect):Trauma exposure ➔ smoking status
B
SE
t/Z
2.01 0.04 0.26 0.18
0.36 0.02 0.09 0.10
5.62*** 2.54* 2.74** 1.77†
Hyperarousal symptoms
BC 95% CI
B
SE
t/Z
BC 95% CI
[0.02, 0.18]
0.67 0.18 0.26 0.15
0.13 0.04 0.09 0.10
4.95*** 3.93*** 2.74** 1.42
[0.05, 0.22]
All path coefficients were derived from 5000 bootstrap samples. BC 95% CI not including zero represents significance of model (bolded). Models were adjusted for age, gender and time since trauma. t-score was used for Path A; Z-score was used for other paths. N = 329. PTSD, post-traumatic stress disorder; BC, bias-corrected; CI, confidence interval; SE, standard error. † p < 0.10. *p < 0.05. **p < 0.01. ***p < 0.001.
80
Stress Health 31: 78–82 (2015) © 2014 John Wiley & Sons, Ltd.
C. A. Gabert-Quillen, A. Selya and D. L. Delahanty
the basis of prior research demonstrating that smoking may help to maintain PTSD symptoms (van der Velden, Kleber, & Koenen, 2008), we ran an alternative model to assess whether smoking status might mediate the relationship between number of traumatic exposures and PTSD/hyperarousal symptoms. The mediation findings were significant for both PTSD symptoms and hyperarousal symptoms. However, comparison of effect sizes (ESs) (Preacher & Kelley, 2011) for the original model (PTSD/ hyperarousal symptoms mediating the relationship between extent of trauma exposure and smoking status) and the new model (smoking status mediates the relationship between extent of prior trauma exposure and PTSD/hyperarousal symptoms) suggest that the original model was the stronger model for both total PTSD symptoms (ES = 0.45 versus 0.08, respectively) and hyperarousal symptoms (ES = 0.80 versus 0.16, respectively).
Discussion The results of the present study add to the existing body of literature demonstrating a link between trauma exposure/PTSD and increased smoking rates (Feldner et al., 2007; Fu et al., 2007) and extend prior findings by demonstrating that PTSD symptoms served as a mechanism for the relationship between number of traumatic exposures and smoking status in college students after controlling for age, gender and time since trauma. Further, results seemed to be primarily due to the significant mediating effect of hyperarousal symptoms. Hyperarousal symptoms have been previously shown to predict smoking and nicotine dependence among participants (Beckham et al., 2005; Feldner et al., 2007; Greenberg et al., 2012; Thorndike et al., 2006). However, to our knowledge, this is the first study to find that hyperarousal symptoms mediated the relationship between number of traumatic exposures and smoking status. Hyperarousal symptoms have been found to play a large role in the maintenance of PTSD symptoms after a traumatic event (Schell, Marshall, & Jaycox, 2004) and to lead to poor health outcomes (Perez, Abrams, Lopez-Martinez, & Asmundson, 2012). Arousal symptoms may also contribute to the role substances play in coping with PTSD symptoms (Jacobsen, Southwick, & Kosten, 2001). Individuals with PTSD may smoke to decrease their hyperarousal symptoms (e.g. difficulty concentrating, hypervigilance and irritability), contributing to the relationship observed in the present study. However, given the exploratory nature of REFERENCES
Trauma Exposure and Smoking
these findings, future work is necessary to replicate these findings and to determine the role that hyperarousal symptoms have in contributing to an increased risk for smoking behaviour. The present findings may help to inform smoking cessation efforts. In a recent smoking cessation study, individuals with PTSD had worse cravings and more severe withdrawal symptoms compared with those without PTSD (Dedert et al., 2012). In addition, cigarette deprivation was shown to increase anxiety in individuals with PTSD (Vujanovic, Marshall-Berenz, Beckham, Bernstein, & Zvolensky, 2010). Results from this study may help to shed light on specific PTSD symptoms that may contribute to difficulties in smoking cessation. As withdrawal symptoms are similar to hyperarousal symptoms, this may lead to worsening of PTSD symptoms and a subsequent need to keep smoking (Jacobsen et al., 2001). There are a few limitations to this study. The crosssectional nature limits the ability to examine how the relationship between PTSD symptoms and smoking status may change over time. The sample was also predominantly female, limiting confidence for generalizing these findings to male college students. Additionally, reports of trauma exposure and PTSD symptoms were assessed via questionnaire; however, research has suggested that questionnaire assessment of post-traumatic symptoms may lead to more accurate symptom reporting than clinical assessment (Schnurr, Friedman, & Bernardy, 2002). We also used a categorical measure of smoking status. Future studies should use more comprehensive measures, especially with respect to the assessment of smoking behaviours (e.g. smoking frequency and quantity). Despite these limitations, the current study indicated that the extent of prior trauma exposure impacts the mental health of college students and their health behaviours and that attention to PTSD symptoms may increase the efficacy of smoking cessation interventions. Attention should also be focused, in particular, on the role of hyperarousal symptoms in contributing to smoking behaviours. Further understanding of these relationships will help to develop more targeted interventions for college student smokers with a trauma exposure.
Acknowledgments The authors wish to thank Bryce Hruska for his advice on revisions of this manuscript. Preparation of this manuscript was supported, in part, by the National Institute of Mental Health (R34 MH073014).
disorder in college students with mixed civilian trauma exposure. Journal of Anxiety Disorder, 22, 1393–1402.
preliminary study. Experimental and Clinical Psychopharmacology, 13(3), 219–228.
Beckham, J. C., Feldman, M. E., Vrana, S. R., Mozley, S.
Breslau, N., Davis, G. C., & Schultz, L. R. (2003).
Adkins, J. W., Weathers, F. W., McDevitt-Murphy, M.,
L., Erkanli, A., Clancy, C. P., & Rose, J. E. (2005). Im-
Posttraumatic stress disorder and the incidence of nicotine, al-
& Daniels, J. B. (2008). Psychometric properties of
mediate antecedents of cigarette smoking in smokers
cohol, and other drug disorder in persons who have experi-
seven self-report measures of posttraumatic stress
with and without posttraumatic stress disorder: A
enced trauma. Archives of General Psychiatry, 60(3), 289–294.
Stress Health 31: 78–82 (2015) © 2014 John Wiley & Sons, Ltd.
81
Trauma Exposure and Smoking Dedert, E. A., Calhoun, P. S., Harper, L. A., Dutton, C. E., McClerno, H. J., & Beckham, J. C. (2012).
C. A. Gabert-Quillen, A. Selya and D. L. Delahanty literature. American Journal of Psychiatry, 158 (8),
exposure and smoking in a population-based sample of young adults. Journal of Adolescent Health, 42(3),
1184–1190
Smoking withdrawal in smokers with and without
Kessler, R. C., Sonnega, A., Bromet, E., Hughes, M., &
posttraumatic stress disorder. Nicotine and Tobacco
Nelson, C. B. (1995). Posttraumatic stress disorder
Schell, T. L., Marshall, G. N., & Jaycox, L. H. (2004). All
Research, 14(3), 372–376.
in the National Comorbidity Survey. Archives of Gen-
symptoms are not created equal: The prominent role
eral Psychiatry, 52(12), 1048–1060.
of
Feldner, M. T., Babson, K. A., & Zvolensky, M. J. (2007). Smoking, traumatic event exposure, and
Lasser, K., Boyd, J. W., Woolhandler, S., Himmelstein,
post-traumatic stress: A critical review of the empiri-
D. U., McCormick, D., & Bor, D. H. (2000). Smoking
cal literature. Clinical Psychology Review, 27, 14–45.
and mental illness: A population-based prevalence
Flood, A. M., McDevitt-Murphy, M. E., Weathers, F. W., Eakin, D. E., & Benson, T. A. (2009). Substance use behaviors as a mediator between posttraumatic
266–274.
hyperarousal
in
the
natural
course
of
posttraumatic psychological distress. Journal of Abnormal Psychology, 113(2), 189–197. Schnurr, P. P., Friedman, M. J., & Bernardy, N. C. (2002). Research on posttraumatic stress disorder:
study. JAMA, 284(20), 2606–2610. McCarthy, S. (2008). Post-Traumatic Stress Diagnostic Scale (PDS). Occupational Medicine, 58, 379.
Epidemiology, pathophysiology, and assessment. Journal
of
Clinical
Psychology,
58,
877–889.
stress disorder and physical health in trauma-
Office of Applied Studies. (2011). Results from the 2010
exposed college students. Journal of Behavioral Medi-
National Survey on Drug Use and Health: Summary
Smyth, J. M., Hockenmeyer, J. R., Heron, K. E.,
cine, 32(3), 234–243.
of National Findings. Rockville, MD: Substance
Wonderlich, S. A., & Pennebaker, J. W. (2008). Prev-
doi:10.1002/jclp.10064
Abuse and Mental Health Services Administration.
alence, type, disclosure, and severity of adverse life
ual. Minneapolis, MN: National Computer Systems.
Perez, L. G., Abrams, M. P., Lopez-Martinez, A. E., &
events in college students. Journal of American College
Frazier, P., Anders, S., Perera, S., Tomich, P., Tennen,
Asmundson, G. J. (2012). Trauma exposure and
H., Park, C., & Tashiro, T. (2009). Traumatic events
health: The role of depression and hyperarousal
Thorndike, F. P., Wernicke, R., Pearlman, M. Y., &
among undergraduate students: Prevalence and asso-
symptoms. Journal of Traumatic Stress, 25(6),
Haaga, D. A. F. (2006). Nicotine dependence, PTSD
ciated symptoms. Journal of Counseling Psychology,
641–648.
symptoms, and depression proneness among male
Foa, E. B. (1995). Posttraumatic Diagnostic Scale Man-
56(3), 450–460.
Preacher, K. J., & Hayes, A. F. (2004). SPSS and SAS
Fu, S. S., McFall, M., Saxon, A. J., Beckham, J. C.,
procedures for estimating indirect effects in simple
Carmody, T. P., Baker, D. G., & Joseph, A. M.
mediation models. Behavior Research Methods, Instru-
(2007). Post-traumatic stress disorder and smoking: A systematic review. Nicotine and Tobacco Research, 9(11), 1071–1084. Greenberg, J. B., Ameringer, K. J., Trujillo, M. A., Sun, P., Sussman, S., Brightman, M.,…Leventhal, A. M.
Health, 57, 69–76.
and female smokers. Addictive Behaviors, 31(2), 223–231. van der Velden, P. G., Kleber, R. J., & Koenen, K. C. (2008). Smoking predicts posttraumatic stress symp-
ments, and Computers, 36(4), 717–731. Preacher, K. J., & Hayes, A. F. (2008). Asymptotic and
toms among rescue workers: A prospective study of
resampling strategies for assessing and comparing in-
ambulance personnel involved in the Enschede
direct effects in multiple mediator models. Behavior
Fireworks Disaster. Drug and Alcohol Dependence, 94 (1-3), 267–271.
Research Methods, 40(3), 879–891.
(2012). Associations between posttraumatic stress
Preacher, K. J., & Kelley, K. (2011). Effect size measures
Vujanovic, A. A., Marshall-Berenz, E. C., Beckham,
disorder symptom clusters and cigarette smoking.
for mediation models: Quantitative strategies for
J. C., Bernstein, A., & Zvolensky, M. J. (2010).
Psychology of Addictive Behaviors, 26(1), 89–98.
communicating
Posttraumatic
Hapke, U., Schumann, A., Rumpf, H. J., John, U., Konerding,
indirect
effects.
Psychological
deprivation
Methods, 16(2), 93–115.
stress in
the
symptoms prediction
and
cigarette
of
anxious
U., & Meyer, C. (2005). Association of smoking and nico-
Read, J. P., Wardell, J. D., Vermont, L. N., Colder, C. R.,
responding among trauma-exposed smokers: A
tine dependence with trauma and posttraumatic stress dis-
Ouimette, P., & White, J. (2013). Transition and
laboratory test. Nicotine & Tobacco Research, 12
order in a general population sample. Journal of Nervous
change: Prospective effects of posttraumatic stress
and Mental Disease, 193(12), 843–846.
on smoking trajectories in the first year of college.
Jacobsen, L. K., Southwick, S. M., & Kosten, T. R.
(11), 1080–1088. Weaver, T. L., & Etzel, J. C. (2003). Smoking patterns, symptoms of PTSD and depression: Preliminary
Health Psychology, 32(7), 757–767.
(2001). Substance use disorders in patients with
Roberts, M. E., Fuemmeler, B. F., McClernon, F. J., &
posttraumatic stress disorder: A review of the
Beckham, J. C. (2008). Association between trauma
findings from a sample of severely battered women. Addictive Behaviors, 28(9), 1665–167.
Supporting information Additional supporting information may be found in the online version of this article at the publisher’s web site.
82
Stress Health 31: 78–82 (2015) © 2014 John Wiley & Sons, Ltd.
Copyright of Stress & Health: Journal of the International Society for the Investigation of Stress is the property of John Wiley & Sons, Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
