Archives of Gerontology and Geriatrics 59 (2014) 528–535

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The contribution of personality to longevity: Findings from the Australian Centenarian Study Jenaleen Law a,*, Robyn L. Richmond b, Frances Kay-Lambkin a,c,d a

Faculty of Medicine, University of New South Wales, Sydney, NSW 2052, Australia Faculty of Medicine, School of Public Health and Community Medicine, University of New South Wales, Sydney, NSW 2052, Australia c Centre for Translational Neuroscience and Mental Health, University of Newcastle, NSW 2308, Australia d National Drug and Alcohol Research Centre, University of New South Wales, Sydney, NSW 2052, Australia b

A R T I C L E I N F O

A B S T R A C T

Article history: Received 4 November 2011 Received in revised form 19 June 2014 Accepted 27 June 2014 Available online 6 July 2014

Objectives: To examine whether centenarians have a unique set of personality traits, which may in part explain their longevity. Methods: 79 Australian centenarians completed the NEO Five Factory Inventory (NEO-FFI), Connor– Davidson Resilience Scale (CD-RISC) and Life Orientation Test Revised (LOT-R) to assess different dimensions of their personalities. Centenarians were asked to answer items of the NEO-FFI, CD-RISC and LOT-R based on current views, and were then asked to recall in the presence of an informant (e.g. carers, offspring) on past personality (i.e. at mid-adult-life). Both sets of answers were recorded and analysed. Results: Centenarians were currently low in Openness and Extraversion and high in Neuroticism, but were low in Openness and high in Neuroticism, Conscientiousness and Extraversion when reflecting on past traits. Currently, centenarians in high care facilities reported higher levels of Neuroticism, as did centenarians who did not socialize. Cognitively intact centenarians reported higher levels of Agreeableness; and males reported lower Neuroticism compared to females when reflecting on past experiences. Discussion: Centenarians were characterized by several personality traits, which facilitated positive health behaviors and thus contributed to their longevity. It is possible that personality may not be static across the lifespan, but instead, reflect advancing age, psychosocial factors and changes in life circumstances. ß 2014 Elsevier Ireland Ltd. All rights reserved.

Keywords: Centenarians Longevity Personality NEO-FFI CD-RISC LOT-R

1. Introduction The association between personality and longevity has received increasing attention in the literature, with personality being proposed as the fourth most important contributor to longevity alongside genetic, physical and biological factors (Lehr, 1982). It is thought that some aspects of adult personalities will emerge in response to crises and other events, but generally, after the age of 20 years, there is increasing consistency in personality up until age 75 (Roberts & DelVecchio, 2000), with some evidence to suggest stability of personality traits even into the eighth and ninth decades of life (Mo˜ttus, Johnson, & Deary, 2011). This enduring personality, referred to as ‘‘personality traits’’, may be partly related to the ability of centenarians to outlive their contemporaries (Perls, Silver, & Lauerman, 1999). Accordingly,

* Corresponding author at: Faculty of Medicine, University of New South Wales, Sydney, NSW 2052, Australia. Fax: +61 2 9313 6185. E-mail address: [email protected] (J. Law). http://dx.doi.org/10.1016/j.archger.2014.06.007 0167-4943/ß 2014 Elsevier Ireland Ltd. All rights reserved.

centenarian study groups worldwide have begun profiling the personality of centenarians, as a group who has attained ‘‘absolute longevity’’ by surviving to 100 years old (Martin et al., 2006; Thomae, 1993). No research has reported on the personality traits of Australian centenarians. 1.1. Absolute longevity As the current cohort of centenarians have lived through difficult and disappointing times such as world wars and the loss of loved ones, it seems plausible that their longevity is not a result of having avoided stress, but rather of having responded to it in a favorable manner (Perls et al., 1999). In other words, centenarians’ personalities may be a key factor in their ability to survive life’s stressful episodes (Martin et al., 1992). The personality traits of centenarians have since been examined using standardized personality inventories, to see whether they have unique characteristics. These studies are difficult to synthesize, given the different approaches in measuring the personality of centenarians, in terms of actual

J. Law et al. / Archives of Gerontology and Geriatrics 59 (2014) 528–535

measurements used and whether information has been provided first-hand (reported by centenarians) or via proxy participants (reported by the centenarian’s family member). A summary of studies on centenarian personalities is provided in Table 1. One of the earliest reports came from The New England Centenarian Study, which reported that centenarians had low levels of Neuroticism, particularly female centenarians, when assessed on the NEO Personality Inventory (NEO-PI) (Perls et al., 1999). Although different inventories were used in the Italian (Tafaro et al., 2009) and Swedish (Samuelsson et al., 1997) studies of centenarians, both agreed that a low anxiety trait was characteristic of their participants. In fact, centenarians in the Swedish study (Samuelsson et al., 1997) reported low scores in hypomania and psychasthenia on the Minnesota Multiphasic Personality Inventory (MMPI), meaning that centenarians were dependable, reliable, mature, conscientious, and less frequently participating in social activities. They were also responsible, easygoing, capable, and relaxed (Samuelsson et al., 1997). The Georgia Centenarian Study found in the first of their three studies that centenarians scored significantly higher on dominance, suspiciousness, and imagination; and scored lower on intelligence, emotional stability and conformity (Martin et al., 1992). The second study, also using the 16 Personality Factor (16PF), confirmed higher scores in suspiciousness, lower scores in intelligence; but also found low stress scores among centenarians (Martin, Long, & Poon, 2002). Results from the third study, which used the NEO-PI, found that centenarians had low levels of Neuroticism, high levels of Extraversion, competence (a facet of Conscientiousness) and trust (a facet of Agreeableness; Martin et al., 2006). Overall, it was felt that the personality configuration of low Neuroticism, high competence and high Extraversion (a resilient personality profile) was common among this sample of

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centenarians in the United States (Martin et al., 2006). Interpreting this result in light of studies described above also substantiates the converse: that high Neuroticism and low Conscientiousness is a risky combination in health. A novel study design used in the Tokyo Centenarian Study (Masui, Gondo, Inagaki, & Hirose, 2006) compared the actual personality test scores for centenarians with a predicted test score for a 100-year-old as extrapolated from younger controls. This method made it possible to separate the age-related changes in personality from the ‘‘longevity personality’’ of centenarians. They also discovered a discrepancy between genders, with female centenarians having higher levels of Conscientiousness and Extraversion; and although Openness was a significant result for centenarians overall, this result was more pronounced in males (Masui et al., 2006). 1.2. Research questions Overall, there is support for low Neuroticism, high Extraversion and high Conscientiousness as being personality traits typical of longevity; but the literature also reveals many conflicting results. Dominance was a prominent trait among US centenarians (Martin et al., 1992), whereas femininity was characteristic of Japanese centenarians (Shimonaka, Nakazato, & Homma, 1996). Even within the same region, initial results described Georgian centenarians as suspicious (using the 16-PF) (Martin et al., 1992), whereas a high level of trust was later detected based on the NEO-PI (Martin et al., 2006). Inconsistencies between studies were possibly due to differences in the personality inventories employed and/or cultural differences, and highlight the need for more research to help distil the longevity traits. Furthermore, longitudinal studies have reported gradual but significant age-related changes in personality traits. Terracciano, McCrae, Brant, and Costa (2005) found that Neuroticism, Extraversion,

Table 1 A summary of studies measuring personality traits in centenarians. Centenarian study

Country

Personality inventory

Sample size (number)

Characteristic traits of centenarians

Martin et al. (1992)

United States (Georgia)

16 Personality Factor

165

Dominance (high) Suspiciousness (high) Imagination (high) Intelligence (low) Emotional stability (low) Conformity (low)

Martin et al. (2002)

United States (Georgia)

16 Personality Factor

55

Suspiciousness (high) Intelligence (low) Stress (low)

Martin et

United States (Georgia)

NEO Personality Inventory

285

Neuroticism (low) Extraversion (high) Competence (high) Trust (high)

Shimonaka et al. (1996)

Japan

Bortner Pattern A Behavior Scale and the Bem Sex-Role Inventory

82

Type B personality (high)

Samuelsson et al. (1997)

Sweden

Minnesota Multiphasic Personality Inventory

86

Hypomania (low) Psychasthenia (low)

Perls et al. (1999)

United States (New England)

NEO Personality Inventory

60

Neuroticism (low)

Masui et al. (2006)

Japan (Tokyo)

NEO Personality Inventory (Japanese version)

70

Openness (high)

al. (2006)

Femininity (high)

Conscientiousness (only high in women) Extraversion (only high in women) Tafaro et al. (2009)

Italy (Rome)

State-Trait Anxiety Inventory

40 (personal communication with researcher)

Anxiety (low)

Optimism (high)

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Openness decreases whereas Agreeableness and Conscientiousness increases as individuals aged. This was also reported by Mo˜ttus et al. (2011), but who additionally found that although levels of Extraversion, Agreeableness, Conscientiousness and intellect declined with age, the very old had higher levels of Agreeableness and Conscientiousness on comparing 81–87 year olds with those aged 69–72. However, a reverse trend was demonstrated by Terracciano et al. (2005) whereby Neuroticism increased and Conscientiousness decreased between ages 75–84 and 85-plus years of age (Terracciano et al., 2005). It was then suggested that across the lifespan, a U-shaped trend existed for Neuroticism (Terracciano et al., 2005) and therefore an inherent problem in studying centenarians (for personality and all other areas) is that most of the centenarians are at the terminal stage of their lives in which there is a global decline in health and function (Perls & Terry, 2003). Therefore, the current personality of centenarians (which has been the focus of previous centenarian studies) may not demonstrate the characteristics associated with living to 100 years old, but rather reflect the personality traits associated with the last few years of the centenarian life. The primary aim of this study was to assess whether centenarians have unique personalities, which may, in part, be responsible for their exceptional longevity. However, this study uses a novel approach to separate the earlier personality traits of centenarians from their current personality, as the use of retrospective personality ratings is one of the central aspects of this study. As Resilience and Optimism and longevity show promising associations, these variables will also be assessed in our study of the centenarian personality. So far, researchers have shown that centenarians high in emotional stability function better in terms of activities of daily living (Samuelsson et al., 1997) and in terms of mental health (Martin, Rott, Poon, Courtenay, & Lehr, 2001). Given that personality traits are seen as individual resources that have possibly helped centenarians attain extreme longevity, we will also examine associations between personality characteristics and other factors including gender, current cognitive function, living arrangements and social relationships. Thus, the specific research questions are the following. First, how can centenarians be characterized by personality traits? Second, have centenarians shown these traits for many years or only in recent years? Third, what other factors (such as cognitive function, living arrangements, gender, education, Optimism, Resilience) influence the centenarian personality profile?

centenarians, information was obtained from centenarians and their carers (often their children). This parallel method of selfreport and informant report is useful when self-reports may be unreliable (McCrae & Weiss, 2007). Written informed consent was obtained from centenarians and/or a family member. This study was approved by the University of New South Wales Human Research Ethics Committee (HREC 07144).

2. Methods

2.4. CD-RISC

2.1. Participants

The 25-item CD-RISC was used to measure centenarians’ Resilience, which was defined as a positive stress coping ability (Connor & Davidson, 2003). This positive capacity to deal with stress has not been quantified in centenarian studies to date. Participants were asked to rate the 25 CD-RISC items as ‘‘not true at all’’, ‘‘rarely true’’, ‘‘sometimes true’’, ‘‘often true’’ or ‘‘true nearly all of the time’’. The CD-RISC is considered a reliable and valid instrument with the test–retest reliability reported to be 0.87 (Connor & Davidson, 2003) and the a = 0.92 (Lamond et al., 2008).

The study recruited a small cross-sectional sample of Australian centenarians. A total of 79 Australian centenarians living in New South Wales (NSW), Queensland (QLD) and Victoria (VIC) participated in this study. Of the participants, 80% were women and 20% were men, and all were Caucasian. The mean age of the participants was 101.3 years old (standard deviation = 1.711, range 100–108 years). These participants were part of the larger Australian Centenarian Study (Richmond, Law, & KayLambkin, 2011; Richmond, Law, & KayLambkin, 2012), which collected information regarding sociodemographics, medical and family history, functional status, and environmental factors. Participants were recruited through systematically calling aged care facilities in NSW, QLD and VIC. One-hundredth birthday congratulatory letters from Queen Elizabeth II, and from the Governor-General and Prime Minister of Australia were used to validate the ages of centenarians. The study was conducted between June and November 2009. The researchers visited the participants individually at their place of residence to perform personality assessments by interview. Two separate visits were often required to complete the assessments, with their carers present. For assessing the past personalities of

2.2. Measures We collected socio-demographic details from participants including date of birth, age, living arrangement, and educational attainment. We used three measures of personality: the NEO Five Factor Inventory (NEO-FFI) (Costa & McCrae, 1992), the Connor Davidson Resilience Scale (CD-RISC) (Connor & Davidson, 2003), and the Life Orientation Test Revised (LOT-R) (Scheier, Carver, & Bridges, 1994). We used the Mini-Mental State Examination (MMSE) (Folstein, Folstein, & McHugh, 1975) to assess cognitive function. In addition, subjective health ratings were obtained by asking participants to rate their level of health as ‘‘excellent’’, ‘‘very good’’, ‘‘good’’, ‘‘fair’’ or ‘‘poor’’ and to categorize their social interactions as ‘‘extensive social interactions’’, ‘‘few social interactions’’ or ‘‘no social interactions’’. 2.3. NEO-FFI This study used the 60-item NEO-FFI to measure the personality domains of Neuroticism, Extraversion, Openness, Conscientiousness and Agreeableness (McCrae & Costa, 2004). Responses were graded on a five-point Likert scale, as either ‘‘strongly agree’’, ‘‘agree’’, ‘‘neutral’’, ‘‘disagree’’ or ‘‘strongly disagree’’. The 240-NEO Personality Inventory (NEO-PI-R) was not used, as it would have been near impossible to conduct the 240-item personality inventory on the centenarian population – our pilot testing found that centenarians were easily fatigued. The NEO-FFI (Japanese version) was also used in the Tokyo-based centenarian study (Masui et al., 2006) whereas a shortened version of the NEO-PI-R (68-items) was used in the Georgia Centenarian Study (Martin et al., 2006). Nevertheless, the NEO-FFI is a widely used measure for measuring personality and the test–retest reliability is uniformly high, ranging from 0.86 to 0.90 for the five scales, while the internal consistency is a = 0.76–0.87 (Holden, 1992).

2.5. LOT-R The 10-item LOT-R (Scheier, 1994) measures the degree of Optimism in terms of ‘‘one’s positive expectations for future outcomes’’ (Scheier, 1994). Responses were graded on a five-point Likert scale as ‘‘strongly agree’’, ‘‘agree’’, ‘‘neutral’’, ‘‘disagree’’ or ‘‘strongly disagree’’. Cronbach’s alpha for the six items was 0.78 and the test–retest reliability was reported to be as high as 0.79 (Scheier, 1994). Optimism has not been specifically examined among centenarians and the LOT-R has not been used in centenarian studies to date.

J. Law et al. / Archives of Gerontology and Geriatrics 59 (2014) 528–535

To assess the consistency in personality across the lifespan, participants were asked to answer the NEO-FFI (and CD-RISC) based on how they currently felt about each of the items. Participants were then asked to recall whether they felt differently about the items when they were younger and the retrospective ‘‘past response’’ was also recorded, i.e. would they have chosen the same response had they been asked this question during their mid-adult-life (30–50 years old)? This method attempts to delineate the personality associated with the last few years of the centenarians’ lives from the past personality traits, which are thought to have enabled centenarians to live to 100 years old. This method was strengthened by informant reports, i.e. centenarians’ offspring and long-time friends, who were present at the interview to validate their answers. However, this method has its limitations, which will be addressed in Section 4.

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males versus female centenarians, and cognitively-intact versus cognitively-impaired centenarians. For the latter, centenarians were divided into ‘‘cognitively-intact’’ and ‘‘cognitively-impaired’’ groups using a cut-off score of 17 on the MMSE. We used the same cut-off as in the Georgia Centenarian Study (Martin et al., 2006), in which the cognitively intact group had a MMSE score of at least 17, and the cognitively impaired group scored 16 or less on the MMSE. Finally, Pearson’s correlations were used to examine associations between the NEO-FFI, LOT-R and CD-RISC scores to check for consistency in responses. Pearson’s correlations also tested associations between the scores on the personality inventories with scores of cognitive function, which was assessed using the MMSE. For significant correlations, the proportion of shared variance between the two significant scores is reported as the square of the Pearson’s correlation.

2.6. Statistical analyses 3. Results One sample t-tests were used to compare the centenarians’ scores with defined population norms. The population norms for the NEO-FFI were obtained from the Baltimore Longitudinal Study on Ageing (McCrae and Costa, 2004). The adult norms for the CDRISC (Connor & Davidson, 2003) and LOT-R (Scheier, 1994) were provided in their respective research articles. In addition to comparing centenarians’ personality scores with the population norms established for the scales of interest, we also compared our sample with the closest age-matched sample available in the literature. One-way ANOVAs were used to compare the means of two samples, for example, comparing the personality scores of

Significant positive correlations were found between past and present Neuroticism (r = 0.925, r2 (shared variance) = 0.855, p = 0.000), past and present Extraversion (r = 0.831, r2 (shared variance) = 0.691, p = 0.000), past and present Openness (r = 0.983, r2 (shared variance) = 0.966, p = 0.000), past and present Agreeableness (r = 0.994, r2 (shared variance) = 0.988, p = 0.000) and past and present Conscientiousness (r = 0.840, r2 (shared variance) = 0.706, p = 0.000). Table 2 displays the means and standard deviations of the personality scores for male, female and total centenarians, in terms of the NEO-FFI, CD-RISC and LOT-R.

Table 2 Means of NEO-FFI, CD-RISC and LOT-R scores for male, female and total centenarians for current and past ratings compared to population norms and age-relevant means for the general population (Connor & Davidson, 2003; McCrae and Costa, 2004; Scheier, 1994). Personality variables

Male centenarians, n = 16

Female centenarians, n = 63

Total centenarians, n = 79

Population norma

Age-specific norm b

M

SD

M

SD

M

SD

M

SD

M

SD

NEO-FFI (current) Neuroticism Extraversion Openness Conscientiousness Agreeableness

15.88 25.94 21.44 34.63 33.35

6.08 5.21 5.56 5.74 4.28

19.43 24.97 21.84 34.52 33.46

8.08 6.48 4.86 5.72 5.62

18.71 25.16 21.76 34.54 33.35

7.81 6.23 4.98 5.69 5.36

15.77* 28.50* 29.32* 33.39 33.48

7.47 6.26 6.11 4.98 6.36

14.76* 28.55* 26.88* 34.28 35.42*

7.55 6.10 5.76 5.85 4.94

NEO-FFI (past) Neuroticism Extraversion Openness Conscientiousness Agreeableness

13.69 30.56 21.94 37.13 32.94

5.21 5.15 5.94 3.70 4.18

18.59 30.08 21.94 36.52 33.40

7.67 6.27 4.87 4.86 5.62

17.59 30.18 21.94 36.65 33.30

7.48 6.03 5.07 4.63 5.38

15.77* 28.50* 29.32* 33.39* 33.48

7.47 6.26 6.11 4.98 6.36

– –

– – – – –

Male centenarians, n = 14

Female centenarians, n = 62

Total centenarians, n = 76

Population normc

Age-specific normd

M

SD

M

SD

M

SD

M

SD

M

SD

CD-RISC (current) Resilience CD-RISC (past) Resilience

72.57

11.66

71.03

10.79

71.32

10.89

71.80

18.4

72.60

16.7

74.86

9.02

73.32

10.61

73.61

10.30

71.80

18.4

–

–

Personality variable

Male centenarians, n = 14

Female centenarians, n = 62

Total centenarians, n = 76

Population norme

Age-specific normf

M

SD

M

SD

M

SD

M

SD

M

SD

LOT-R (current) Optimism

14.57

4.27

15.00

3.38

14.92

3.53

14.33

4.28

14.90

3.5

Personality variables

*

t-test comparing centenarian score to norm was p < 0.05. Mean (and standard deviation) for study participants in the Baltimore Longitudinal Study on Ageing, aged 19–93years, N = 1492 (McCrae & Costa, 2004). b Mean (and standard deviation) for study participants aged 65–97 years, N = 449 (Chapman et al., 2007). c Mean (and standard deviation) for study participants in the normative sample published by the scale developers, mean age = 43.8 (SD = 15.4) years, N = 194 (Connor & Davidson, 2003). d Mean (and standard deviation) for study participants aged 83.7 years, N = 25 (Montross et al., 2006). e Mean (and standard deviation) for study participants in the normative sample published by the scale developers, college students, N = 2055 (Scheier et al., 1994). f Mean (and standard deviation) for study participants aged 71 years and over, N = 274 (Glaesmer et al., 2012). a

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J. Law et al. / Archives of Gerontology and Geriatrics 59 (2014) 528–535

3.1. Comparisons with general population norms One sample t-tests evaluated whether the total centenarian mean scores were significantly different from the means of the general population for current personality ratings and ratings based on recall of past personality traits (see Table 2). This was done by comparing centenarian test scores to established normative values for the general population. The population norms for the NEO-FFI were based on 1492 adults 19–93 years old on the 60-item version of the scale (McCrae and Costa, 2004). The normative sample for the CD-RISC (N = 194) was a primary outpatient population (mean age 43.8 years, Connor & Davidson, 2003), while the normative sample for the LOT-R (N = 2055) were college students in their first year of their degree (Scheier, Carver & Bridges, 1994). The main findings were that centenarians were currently significantly lower in Extraversion and Openness than the population norm for the scale, and significantly higher on Neuroticism. The centenarian group scored similarly on Resilience when compared to population norms (see Table 2) and they were not significantly different from the general population in terms of CD-RISC and LOT-R scores. 3.2. Comparisons with age-matched samples In addition to comparing centenarians’ personality scores with population norms established for the scales of interest, we also compared our sample with the closest age-matched sample available in the literature. For the NEO-FFI, raw mean scores were compared for our Centenarians at the time of assessment (current), relative to those aged 65–97 years (average 75 years), recruited as outpatients from a primary care setting in the United States (N = 449, aged 65–97 years, Chapman, Lynes, & Duberstein, 2007). Our sample reported significantly higher Neuroticism scores, and significantly lower scores on Extraversion, Openness and Conscientiousness, than did the Chapman et al. (2007) sample (see Table 2). No significant difference in Resilience was found between our centenarian sample and the closest in age reported in the literature (N = 25, aged 83.7 years, Montross et al., 2006). The same was true for Optimism (N = 274, aged 71 years and over; Glaesmer et al., 2012). 3.3. Gender One-way ANOVAs compared the current and past personality scores between females and males. We found that male centenarians (n = 16, M = 13.69) had lower levels of Neuroticism compared to females (n = 63, M = 18.59), when both were reflecting on past personalities (F(1,78) = 5.82, p = 0.018). There were no significant differences for the other domains.

indicating that as cognitive impairment increased, scores on the Extraversion scale decreased. No other significant correlations were found. To account for the potential confound of cognitive impairment on Agreeableness and Extraversion (current), the mean scores for these traits were re-calculated to include only those who were cognitively intact; Agreeableness (present) = 34.12; Agreeableness (past) = 34.12; Extraversion (current) = 25.00. These revised means were compared with the test norms for the NEO-FFI. Relative to the norm of 32.84, participants without cognitive impairment were significantly higher on Agreeableness currently (t(57) = 2.101, p = 0.040) and in the past (t(57) = 2.073, p = 0.043). In addition, centenarians without cognitive impairment were significantly lower on Extraversion than the norm of 27.69 (t(57) = 3.228, p = 0.002). 3.5. Schooling and education One-way ANOVAs with Bonferroni post hoc analyses examined the relationship between current scores on the NEO-FFI, CD-RISC and LOT-R and levels of educational attainment. In our sample, 39% left school with no qualifications, 10% finished secondary school, 10% received a tertiary education, 18% completed a trade certificate or apprenticeship, and 22% received a diploma or other. There were no significant mean differences for any of the personality traits in terms of educational attainment. 3.6. Current living arrangement One-way ANOVAs examined the relationship between current scores on the NEO-FFI, CD-RISC and LOT-R and current living arrangement. Participants currently living in nursing homes were categorized into ‘‘high care’’ (n = 42) while those in hostels and in private dwellings were categorized as living in ‘‘low care’’ (n = 37). We found that centenarians living in high care facilities reported significantly high levels of Neuroticism (M = 20.48, SD = 7.41) compared to those currently living in low care settings (M = 16.70, SD = 7.88, F(1,78) = 4.81, p = 0.031) (Fig. 1). 3.7. Current social participation One-way ANOVAs compared the current scores on the NEO-FFI, CD-RISC and LOT-R and current social participation. We found that centenarians who had ‘‘at least a few social interactions’’ (n = 51, M = 17.31, SD = 8.00) had significantly lower Neuroticism scores compared to those who did not currently socialize at all (n = 22, M = 21.13, SD = 7.08, F(1,75) = 6.552, p = 0.013). Current Resilience, as measured by the CD-RISC, was also significantly associated with

3.4. Cognitive function One-way ANOVAs compared current scores on the personality inventories (NEO-FFI, CD-RISC and LOT-R) with current MMSE scores. The only difference between cognitively intact and impaired centenarians was that cognitively intact centenarians (M = 34.19, SD = 4.64) had higher levels of Agreeableness compared to cognitively impaired centenarians (M = 30.85, SD = 5.29, F(1,70) = 5.02, p = 0.029). Pearson correlations between actual MMSE scores and personality produced similar associations, with significant positive correlations found for current Agreeableness (r = 0.331, p = 0.005) and past Agreeableness and MMSE score (r = 0.347, p = 0.003), indicating that as Agreeableness increased, so did the cognitive performance of centenarians on the MMSE. In addition, a significant negative correlation was found between current Extraversion and MMSE scores (r = 0.275, p = 0.020),

Fig. 1. Current personality scores according to current living arrangement, where N = Neuroticism, E = Extraversion, O = Openness, A = Agreeableness, C = Conscientiousness, R = Resilience, Opt = Optimism.

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current social participation, with centenarians reporting ‘‘at least a few social interactions’’ being significantly more resilient than their counterparts with no social contacts (M = 73.12 vs. M = 67.39, F(1,75) = 4.564, p = 0.036). 4. Discussion Prior studies reported that centenarians were currently low in Neuroticism (Martin et al., 2006; Perls et al., 1999) and high in Conscientiousness and Extraversion (Martin et al., 2006; Masui et al., 2006), but did not evaluate whether these traits developed with older age or whether centenarians had possessed these personality traits throughout their lives. Using our approach in assessing the current and past personality of centenarians, validated by informant reports, centenarians were found to be presently high in Neuroticism, low in Extraversion and Openness, with past personalities described as high in Neuroticism, Conscientiousness and Extraversion, and low in Openness. Scores for ‘present’ and ‘past’ personalities were consistent for high Neuroticism and low Openness, and centenarians were higher on these domains than established population norms for the NEO-FFI. Given scores for our centenarians on each of the personality subscales were significantly highly and positively correlated, with 60–97% of the variation in current personality associated with past personality ratings, it would appear that our sample felt these personality traits were somewhat enduring across their lifespan. This is consistent with the rank-order stability definition of personality traits over the lifespan, in which personality rankings do not tend to change across different time points (Funder, 2010). However, high Extraversion in the past was significantly correlated with low Extraversion currently, supporting previous work by Lucas and Donnellan (2011), who reported that Extraversion generally declined over the lifespan, and Terracciano et al. (2005) who specifically described declining Extraversion with older age. For Extraversion, then, our study adds weight to the idea that some personality traits may not necessarily be static, but reflective of life circumstances, sculpted by advancing age, crises and other life events. Greater emphasis is placed on the ‘‘past’’ personality of centenarians in this section, as we believe the past personality traits (demonstrated over the majority of their lives) had greater influence on their ability to live to 100 years old. 4.1. Extraversion The NEO-FFI items for which centenarians reported the most difference between current and past states were within the Extraversion domain such as, ‘‘I often feel as if I’m bursting with energy’’, ‘‘My life is fast-paced’’ and ‘‘I am a very active person’’. These questions were possibly influenced by age-related changes more so than other items of the NEO-FFI. Given the age-related deteriorations and self-reported experiences of fatiguing easily (which was also identified from interviews), the ability for centenarians to lead a fast and active life should be considered within the context of their physical limitations. In our sample, 69% centenarians experienced sight loss, 73% experienced hearing loss, and many required mobility aids. Such physical limitations likely contributed to lower scores on the Extraversion domain, and we suggest that devising more appropriate personality measures for very old individuals may be of interest to future studies. In contrast, centenarians were characterized as having high Extraversion levels in the past, which may have conferred health benefits given Extraversion is associated with greater subjective wellbeing, vitality and longevity (Givens et al., 2010). Givens et al. (2010) also found higher levels of Extraversion in centenarian offspring, even when compared with an adult sample of a lower mean age. We speculate that extroverted persons tend to be socially well-connected, and are therefore able to depend on the

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people within their rich web of social networks at times of difficulty, which would serve to minimize the impact of stressful events on themselves. It may also be that extroverted individuals are at ease with seeking the company of others, and this may be beneficial for health as shown in studies which describe good social connections being fundamental to psychological well-being and mental health(Kawachi & Berkman, 2001). 4.2. Openness Previous research among Japanese Centenarians reported that high levels of Openness exist in this cohort (Masui et al., 2006; Shimonaka et al., 1996). In contrast, Openness was low for present and past reports in our centenarian sample, in comparison to the age-specific sample. Openness has not received much attention as a health-related factor and at present, the effects of Openness even in younger individuals, who comprise the bulk of current healthrelated personality research, is unclear. On one hand, high Openness is correlated with a sense of adventure (Costa & McCrae, 1992), which is clearly limited by current health status among centenarians. On the other hand, people who are low in Openness tend to be more conventional and pragmatic (Costa & McCrae, 1992). Thus, we propose that a practical approach to life (as embodied by low past/present Openness) has enabled centenarians to find realistic solutions to problems and better adapt to the limitations encountered with advanced age. 4.3. Agreeableness Our centenarian sample was significantly lower in current levels of Agreeableness compared to the age-specific comparison group, but not the population norm. Agreeableness is associated with warmth, amiability and trust (Chapman et al., 2007). One explanation for this result may be that our sample were fatigued by our research assessment interview, which was quite lengthy and required sustained attention over several hours face-to-face with an interviewer. In contrast, the age-specific sample (Chapman et al., 2007) was engaged in a longitudinal research project, and completed their personality assessment in pen-and-paper format, at a time convenient to them, returning their responses by post, potentially with more ‘‘agreeable’’ participants self-selecting into the study. This possibility is strengthened, with the population norm for Agreeableness being close to our centenarian sample (rather than the age-specific sample). 4.4. Neuroticism It is unclear why our centenarians reported significantly higher levels of Neuroticism than did the population of 19–93 year olds providing the normative data for the scale. There is strong evidence that high levels of Neuroticism are associated with disease, particularly in relation to the development and recurrence of coronary heart disease (Boyle et al., 2004; Everson-Rose et al., 2006; Suls & Bunde, 2005), and that low levels are more commonly associated with survival (Miller, Smith, Turner, Guijarro, & Hallet, 1996). Studies in much younger cohorts found that survivors were relatively relaxed and less likely to worry (Terracciano, Lockenhoff, Zonderman, Ferrucci, & Costa, 2008; Wilson et al., 2005). In centenarian studies, subjects were often characterized as having low Neuroticism (Martin et al., 2006; Perls et al., 1999) and being less prone to anxiety (Samuelsson et al., 1997; Tafaro et al., 2009). However, the underlying association is complex, and further research is needed to elicit the exact causal pathways between Neuroticism, health and disease, given the findings of the current study. We found that males demonstrated lower levels of Neuroticism compared to females, but this result should be interpreted with caution due to the lack of statistical power from

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the small number of male centenarians examined (n = 16). However, it is important to note that our sample included significantly more females than did both the normative sample of the NEO-FFI, and the age-specific comparison sample. Typically, women score higher than men in Neuroticism (see Lynn & Martin, 1997 for a meta-analysis), and so the over-representation of females in our sample could well have contributed to this particular result. 4.5. Conscientiousness High Conscientiousness is increasingly recognized as a predictor of survival. Studies have found lower all-cause mortality rates among individuals with high Conscientiousness (Iwasa et al., 2008; Martin, Friedman, & Schwartz, 2007; Terracciano et al., 2008), and these were corroborated by studies that reported high Conscientiousness among long-lived individuals such as centenarians (Martin et al., 2006; Masui et al., 2006). In a meta analysis conducted on the relationship between Conscientiousness and longevity, Bogg and Roberts (2004) revealed that Conscientiousness-related traits were negatively related to all risky health behaviors (e.g. tobacco use, excessive alcohol/drug use, violence, risky sexual behaviors, suicide), and positively related to beneficial behaviors (e.g. good diet, exercise) (Terracciano & Costa, 2004). Other authors have confirmed these relationships, for example, high Conscientiousness and regular exercise (Terracciano et al., 2008), a tendency to dutifully follow medical advice and better self-control (Marshall, Wortman, Vickers, Kusulas, & Hervig, 1994). It therefore seems that individuals with higher Conscientiousness may be more capable of maintaining healthy habits and thus good health. 4.6. Cognitive function One study compared personality scores on the NEO-FFI to MMSE scores but found no significant differences for any of the personality traits in terms of cognitive function (Martin et al., 2006). In contrast to Martin et al’s (2006) study, we found that higher cognitive scores were associated with higher scores on Agreeableness. Previous research has indicated that, generally, Agreeableness increases with increasing age (Terracciano et al., 2005). Although we had few cognitively impaired participants, our findings reflect those of psychogeriatric studies, which generally support the belief that a negative personality change is common in dementia (e.g. Aitken, Simpson, & Burns, 1999). 4.7. Social interactions We found that centenarians who participated in a few social activities had lower levels of Neuroticism compared to those who did not participate at all, which supports the New England Centenarian Study findings that centenarians who were more socially integrated report better health and higher morale than those who were not socially integrated (Perls et al., 1999). Past studies have also shown that individuals who did not have a rich social network were more prone to mental illnesses, particularly depression (Kawachi & Berkman, 2001), which is a subfacet of Neuroticism (Costa & McCrae, 1992; Smith & MacKenzie, 2006). 4.8. Living arrangement We found that centenarians currently residing in high care facilities demonstrated higher Neuroticism than those in low care facilities. This finding supports Australian statistics, which report a particularly high prevalence of depression in aged care settings (Beyondblue, 2009). The reason why centenarians in this study did not currently demonstrate low levels of Neuroticism may be

related to their current living arrangement. On personal communication, we found that of the 285 participants in the Georgia Centenarian Study, many (45%) were still living in private homes, and only 37% lived in nursing homes and 18% lived in assisted living [Martin, P 2009, personal communication, December 2009]. In addition, the age-specific sample for Chapman et al. (2007) were all living in community dwellings. On the other hand, a vast majority of our participants (76%) were living in nursing homes due to our recruitment strategies and potentially contributing to the higher levels of Neuroticism reported by our participants in comparison to the two samples used in Table 2. 4.9. Methodological limitations This study has several limitations. Firstly, centenarians in this study were from NSW, QLD and VIC, and results cannot be generalized to the broader centenarian community in Australia. In addition, assessments of centenarians are challenging, so the more comprehensive NEO-PI could not be used, and not all personality facets could be examined. Furthermore, although we have used a novel approach to assess the past personalities of centenarians, the reliability of this recall is controversial. In an attempt to address this issue, family members who were present at the centenarian interviews, and who knew the centenarians when they were young, were asked to take note of any items for which the centenarian’s response was not in accord with their views of them. This was brought to the attention of the researcher at the conclusion of the personality section, and a consensus was generally reached between the centenarian and family member. However, this rarely occurred, and family members mostly agreed that the centenarians had good insight of their personalities (past and present). Using this parallel method of informant self-report on personality scales is not an uncommon practice in this area, and can be used in almost every context in which self-reports are normally used, and are particularly valuable when self-reports may be unreliable (McCrae & Weiss, 2007). There is also a solid body of evidence emerging that ratings by informants well acquainted with the target provide reliable, stable, and valid assessments of personality traits (McCrae & Weiss, 2007). Even so, this method of measuring personality is still problematic, and caution in generalizing these results should be taken. Mention should also be made of the potential influence of secular trends on the development of personality, for example, social trends and environmental influences that have, in previous longitudinal research, been associated with Extraversion and Neuroticism (Terracciano, 2010). We cannot determine whether our results reflect the characteristics of any person who reaches exceptional old age, or are as a result of a birth cohort effect, that is, a generational effect from growing up in a particular era and not necessarily linked to developmental patterns. Terracciano (2010) suggests that one way to examine this issue further is to include multiple birth cohorts, across cultural and social groups, and this certainly remains an important direction for future research to consider. As offspring of centenarians also demonstrate lower mortality than other members of their birth cohort (Perls et al., 1999), centenarian offspring studies as per Givens et al. (2010) would also be of value. In conclusion, our findings show that centenarians are characterized by a specific set of personality traits. As a group, centenarians were currently low in Extraversion and Openness and high in Neuroticism, and were low in Openness and high in Neuroticism, Conscientiousness and Extraversion when reflecting on past traits. Further, we found that personality traits were influenced by internal factors such as cognitive function and external factors such as living arrangement.

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