Previous research has shown an association between certain personality characteristics and suicidality. Methodological differences including small sample sizes and missing adjustment for possible confounding factors could explain the varying results. The aim of this study was to assess the impact of the Big Five personality dimensions on suicidality in a representative population based sample of adults.
Interviews were conducted in a representative German population-based sample (n=2555) in 2011. Personality characteristics were assessed using the Big Five Inventory-10 (BFI-10) and suicide risk was assessed with the Suicidal Behaviors Questionnaire-Revised (SBQ-R). Multivariate logistic regression models were calculated adjusting for depression, anxiety, and various sociodemographic variables.
Neuroticism and openness were significantly associated with suicide risk, while extraversion and conscientiousness were found to be protective. Significant sex differences were observed. For males, extraversion and conscientiousness were protective factors. Neuroticism and openness were found to be associated with suicide risk only in females. These associations remained significant after adjusting for covariates.
Citation: Blüml V, Kapusta ND, Doering S, Brähler E, Wagner B, Kersting A (2013) Personality Factors and Suicide Risk in a Representative Sample of the German General Population. PLoS ONE 8(10): e76646. https://doi.org/10.1371/journal.pone.0076646
Editor: Brett Thombs, McGill University, Canada
Received: July 15, 2013; Accepted: September 2, 2013; Published: October 4, 2013
Copyright: © 2013 Blüml et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: The authors have no support or funding to report.
Competing interests: The authors have declared that no competing interests exist.
Suicide is a major public health issue accounting for over one million deaths per year making it the tenth leading cause of death worldwide . Known risk factors include age, sex, presence of psychiatric disorders, and other sociodemographic characteristics such as religious denomination and unemployment [1,2].
An increasing body of evidence suggests an association between certain personality factors and suicidality . Past research applied a variety of different concepts of personality complicating definite conclusions about the influence of personality traits on suicidality . The five-factor model of personality is one of the most comprehensive and best established models to assess personality [4,5]. It aims to empirically describe personality along five major dimensions, namely neuroticism, extraversion, openness, agreeableness, and conscientiousness [4,5]. These five personality dimensions show clear heritable characteristics [6,7] and have been shown to be associated with different psychiatric disorders such as anxiety, depressive, substance use, and personality disorders [8,9,10,11].
In a systematic review of the association between personality traits and suicide risk, Brezo et al. (2006) found neuroticism and extraversion to be the most consistently replicated characteristics to be associated with suicide-related behaviors. Specifically, higher neuroticism was associated with suicidal ideation, suicide attempts, and completed suicide, while extraversion was found to be a resilience factor for suicidality . In a clinical sample of depressed adults 50 years of age or older, higher scores of neuroticism and openness were associated with suicidal ideation . Similar results in another sample of depressed adults 50 years of age or older were reported for the association between personality facets (sub-scales of the Big Five dimensions) and suicide attempts . High neuroticism and low extraversion together with low agreeableness and low conscientiousness were reported to be associated with increased suicidal ideation in a college student sample , whereas only neuroticism was found to be a predictor for suicide ideation in another sample of university students . Additionally, the influence of personality traits on suicidality was found to be influenced by gender . In a sample of young adults, neuroticism was associated with suicidal ideation in females, while conscientiousness was negatively associated with suicidal ideation in males . In one of the few studies investigating personality characteristics and completed suicide, a personality style characterized by a combination of high neuroticism and low extraversion was found to increase suicide risk in an adult sample in rural China .
However, a major limitation of these studies, which possibly accounts for the varying results, is that they have been based on different clinical and non-representative subsamples. Previous research on the association between personality factors and suicidality has also been criticized for a lack of controlling for potentially important covariates such as the presence of psychiatric disorders or certain sociodemographic characteristics known to influence suicide risk . Although large scale research primarily used aggregated data to conduct state-level analyses of the association between personality dimensions and suicide rates [19,20], such study designs are incapable to adjust for individual psychiatric comorbidity.
Aims of the study
Considering all of the above it was the aim of this study to assess the relationship between the Big Five personality dimensions and suicidality in a representative sample of the German general population while controlling for anxiety and depression and other possible confounding sociodemographic factors. To our knowledge, this is the first study to assess this association in a representative population-based sample.
A cross-sectional questionnaire survey of a randomly generated population sample in Germany was conducted through face-to-face contact by a demographic consulting company (USUMA, Berlin, Germany). The fieldwork was conducted in April and May 2011. Random multistage sampling procedures were used. Germany was divided into 258 sampling areas representing Eastern and Western parts as well as different (rural and urban) regions of the country. Members of households in the selected areas were randomly chosen. The inclusion criteria were that participants were aged at least 18, able to read and to understand German. The sample was designed to be representative of the German population in terms of age, gender, and education. The selected individuals were personally approached by interviewers, who collected the sociodemographic information face-to-face; the respondents then themselves anonymously filled out the self-report questionnaires. The interviewers did not read or evaluate the results. Contact was attempted for 4,386 subjects, of whom 4,327 fitted the criteria. A total of 2,555 subjects agreed to participate.
All the participants volunteered and received a data protection declaration in agreement with the Helsinki Declaration. The study was approved by the Ethics Committee of the Medical Faculty of the University of Leipzig. It was also approved according to the ethical guidelines of the “German Professional Institutions for Social Research” [Arbeitskreis Deutscher Markt- und Sozialforschungsinstitute, Arbeitsgemeinschaft Sozialwissenschaftlicher Institute, Berufsverband Deutscher Markt und Sozialforscher].
Detailed sociodemographic characteristics were collected from each study participant. The following psychometrically validated instruments were used to assess personality, anxiety, depression, and suicidality in the population sample.
Big Five Inventory-10 (BFI-10) 
The BFI-10 is a short self-rating instrument based on the Big Five Inventory-44  reducing the original number of items from 44 to 10 with two items measuring each of the five personality dimensions (extraversion, agreeableness, conscientiousness, neuroticism, openness). The German version of the instrument was used . It was shown to have acceptable psychometric properties with a clear five factor structure and good external validity .
The German version of the GAD-7 (original version :) was used to measure anxiety symptoms. It consists of 7 items with total scores ranging from 0 to 21. A score of ≥ 10 has been identified as indicating a possible diagnosis of generalized anxiety disorder in the general population . The GAD-7 was also shown to be useful in identifying people with panic disorder, social anxiety disorder, and posttraumatic stress disorder . It was shown to have high internal consistency and reliability . For the purpose of this study a cut-off score of ≥ 10 was used to identify participants with moderate or severe anxiety symptoms.
Patient Health Questionnaire – 9 (PHQ-9) 
Depression was assessed using the German version of the depression scale of the PHQ . Each of its nine items is scored on a four-point Likert scale and describes one of the DSM-IV criteria for major depressive disorder. Numerous studies have shown excellent validity and reliability of the PHQ-9 [28,29]. A cut-off score of ≥ 10 has been recommended for detecting the presence of severe depressive symptoms and has been used in our study .
Suicidal Behaviors Questionnaire-Revised (SBQ-R) 
Suicidality was assessed using the SBQ-R. It is a short, 4-item self-report questionnaire measuring different dimensions of suicidality: lifetime suicide ideation and / or suicide attempt, frequency of suicidal ideation over the past twelve months, threats of suicide attempt, and self-reported likelihood of suicidal behavior in the future. It has been validated in the adult general population and showed good internal consistency and reliability . A cut-off score of ≥ 7 was recommended for use in general population samples for identifying groups at risk of suicide. The validity of the SBQ-R was established by differentiating between individuals with suicide-risk status from non-suicidal groups. Suicide-risk status was defined as past or present suicidal behavior (i.e. suicide attempts or suicide ideation). The SBQ-R showed very good sensitivity (93%) and specificity (95%), a positive predictive value of 70% and a negative predictive value of 99% for identifying individuals with suicide-risk status . The SBQ-R was translated into German and back-translated by a native speaker. The German version of the SBQ-R in the present study had adequate internal consistency (α = 0.76) .
All analyses were calculated using IBM SPSS Statistics 21. Chi-square tests were calculated for group differences for categorical variables and independent t-tests for metric variables. Binary logistic regression analyses were conducted to assess predictors of suicide risk with multivariate models incorporating covariates. Alpha for all analyses was p < 0.05 and all reported p-values are two-tailed.
In total, 2555 persons participated in the study. Due to missing data in one of the key instruments (BFI-10, SBQ-R, PHQ-9, GAD-7) 128 participants had to be excluded in this study. The final dataset comprised 2427 participants with a mean age of 49.3 years (SD±18.1, range: 14-97). Further sample characteristics are shown in table 1.
|East vs. West of Germany||East of Germany||473 (19.5%)|
|West of Germany||1954 (80.5%)|
|Urbanity||Rural area||2123 (87.5%)|
|Urban area||304 (12.5%)|
|Family Status||Married, living together||1174 (48.4%)|
|Married, living apart||38 (1.6%)|
|Religious Denomination||Protestant||956 (39.4%)|
|No denomination||545 (22.5%)|
|No information||55 (2.3%)|
|Employment status||Employed||1208 (49.8%)|
|In training / schooling||211 (8.7%)|
|No information||3 (0.1%)|
|Household income||<1250€/month||567 (23.4%)|
|1250 to 2500€/month||1094 (45.1%)|
|No information||68 (2.8%)|
Mean scores of the PHQ-9, GAD-7, and SBQ-R and prevalence rates of depression, anxiety, and suicidality for the whole sample and separated by sex are given in table 2. Significant sex differences were observed for the mean scores of the PHQ-9, GAD-7, and SBQ-R and for the presence of anxiety. The scores of the BFI-10 are shown in table 3. Significant sex differences were also found in the personality dimensions agreeableness, conscientiousness, and neuroticism.
|Depression (PHQ-9)||Mean scores||3.22 (SD ±3.92)||2.83 (±3.63)||3.58 (SD ±4.14)||-4.69||<0.001|
|Depression (PHQ ≥ 10)||189 (7.8%)||80 (6.9%)||109 (8.6%)||0.079|
|No depression (PHQ < 10)||2238 (92.2%)||1073 (93.1%)||1165 (91.4%)|
|Anxiety (GAD-7)||Mean scores||2.51 (SD ±3.05)||2.22 (SD ±2.78)||2.78 (SD ±3.26)||-4.52||<0.001|
|Anxiety (GAD ≥ 10)||108 (4.4%)||4ß (3.5%)||68 (5.3%)||0.016|
|No anxiety (GAD < 10)||2319 (95.6%)||1113 (96.5%)||1206 (94.7%)|
|Suicidality (SBQ-R)||Mean scores||3.79 (SD ±1.77)||3.71 (SD ±1.56)||3.86 (SD ±1.94)||-2.11||0.035|
|Suicide risk (SBQ-R ≥ 7)||112 (4.6%)||47 (4.1%)||65 (5.1%)||0.134|
|No suicide risk (SBQ-R < 7)||2315 (95.4%)||1106 (95.9%)||1209 (94.9%)|
|Personality factors||Extraversion||3.40 (SD ±0.9)||3.44 (SD ±0.88)||3.36 (SD ±0.92)||2.20||0.028|
|Agreeableness||3.38 (SD ±0.72)||3.29 (SD ±0.74)||3.46 (SD ±0.7)||-5.85||<0.001|
|Conscientiousness||3.96 (SD ±0.81)||3.93 (SD ±0.83)||3.98 (SD ±0.79)||-1.39||0.165|
|Neuroticism||2.57 (SD ±0.8)||2.43 (SD ±0.76)||2.70 (SD ±0.81)||-8.22||<0.001|
|Openness||3.17 (SD ±0.88)||3.05 (SD ±0.88)||3.30 (SD ±0.86)||-7.08||<0.001|
The logistic regression model with suicide risk (SBQ-R score ≥ 7) as the dependent variable is shown in table 4. The Hosmer-Lemeshow-test indicated a satisfactory model fit (χ2=4.41, p=0.82) and the correlation matrix showed no signs of multicollinearity. The personality factors extraversion, conscientiousness, neuroticism, and openness, and the presence of depression were significantly associated with suicidality.
|East vs. West||-0.12||0.31||0.14||0.89||0.48-1.65||0.71|
Next, the results of the logistic regression analyses performed separately for males and females are shown in tables 5 and 6. For males, extraversion, conscientiousness, and the presence of anxiety were significantly associated with suicidality. The model fit was satisfactory (Hosmer-Lemeshow-test: χ2=7.24, p=0.51) and no signs of multicollinearity were detected. In the model for females, neuroticism, openness, and the presence of depression were significantly associated with suicidality. Again, the model fit was satisfactory (Hosmer-Lemeshow-test: χ2=9.89, p=0.27) and no multicollinearity was detected.
|East vs West||-0.23||0.44||0.26||1.25||0.53-2.99||0.61|
|East vs West||-0.29||0.48||0.36||0.75||0.29-1.92||0.55|
This study of the relationship between personality dimensions based on the Big Five model and suicidality in a representative sample of the German general population yielded several noteworthy findings. An increased suicide risk indicated by a SBQ-R score ≥ 7  was detected in 4.6% (n=112) of the respondents. The SBQ-R is an instrument which taps into different dimensions of suicidality including current and lifetime suicide ideation and attempt and self-reported likelihood of suicidal behavior in the future . Therefore, a direct comparison with studies measuring only one aspect of suicidality is not recommendable. Nevertheless, similar results measuring suicidality in general population samples have recently been reported. A recent German population based study found a prevalence of suicidal ideation of 8.0%  and a European study reported a prevalence of 7.2% for lifetime suicide ideation and 1.3% for suicide attempts .
The multivariate logistic regression analyses showed that neuroticism and openness are associated with suicidality, while extraversion and conscientiousness are inversely associated with suicide-related behavior, thus posing protective factors. Overall, these findings corroborate previous research on the association between the big five personality dimensions and suicidality. Neuroticism, a personality trait frequently associated with negative affectivity and maladaptive coping strategies [34,35], has consistently been found to be associated with increased suicidality [3,12,13,14,15,18]. Likewise, extraversion has regularly been associated with reduced suicidal behavior [3,14,18]. Extraversion has been described as a tendency towards positive affect and low levels of extraversion are related to hopelessness and a negative outlook on life [34,36]. There is less evidence for the impact of the remaining personality dimensions on suicidality. In line with our results, openness was reported to be associated with suicide ideation in a sample of elderly depressed patients . The authors argued that on the one hand openness may increase the likelihood of reporting suicide ideation as measured by self-report instruments and on the other hand it may decrease actual risk of death by suicide, presumably by increasing the chance of clinical intervention through timely reporting of suicidality . High levels of openness have also been linked to cognitive distortion, lack of insight, and impulsivity, which could also explain the association with suicide-related behaviors in our sample [37,38]. Finally, low levels of conscientiousness have been found to be associated with increased suicidal ideation in previous studies [14,17]. There is evidence that low levels of conscientiousness are related to impulsive tendencies and substance use disorders as well as deficits in active coping strategies [8,39,40], which might explain increased suicide risk in these individuals.
The presence of moderate to severe depressive symptoms was the only other variable with a significant impact in the multivariate regression model. Depression is a well-known risk factor for suicidality . No other variables showed a significant association with suicide risk including well established risk factors for completed suicide such as male sex, older age, or unemployment . Additionally, it can be hypothesized that there are characteristic differences between suicide completers and persons with elevated suicide risk as assessed by self-report questionnaires such as the SBQ-R in our study. For example, it is known, that women are more likely to engage in nonfatal suicide attempts while the risk for completed suicide is greater in men [42,43,44].
In the separate analyses for males and females a distinctive pattern of personality factors was associated with suicide risk. For males, low levels of extraversion and low levels of conscientiousness were significant predictors. Velting (1999) also reported low levels of conscientiousness to be associated with suicidal ideation and a facet level analysis of the conscientiousness personality dimension identified lack of self-discipline as the most powerful predictor of suicidal ideation in men. On the other hand, low extraversion has not been previously reported to be specifically associated with male suicide risk, but is a well-established risk factor for both sexes.
Interestingly, high anxiety levels were associated with suicide-related behaviors in the male population, an association not found in women. These findings are in contrast to previous research on the association between anxiety disorders and suicidality, which found anxiety disorders to be an independent risk factor for suicide ideation and attempt for both sexes [45,46]. Cougle et al. (2009) report that for women all four anxiety disorders (social anxiety disorder, posttraumatic stress disorder, generalized anxiety disorder, panic disorder) were predictive of suicidality, while for men only posttraumatic stress disorder and panic disorder were identified as risk factors.
In our study, suicide-related behavior of females was predicted by high levels of neuroticism and openness and the presence of moderate to severe depressive symptoms. Velting (1999) also found neuroticism to be associated with suicide ideation in females. Neuroticism has strong links with a vulnerability for the development of depressive episodes and the prevalence of depression is known to be substantially higher in women [47,48]. This interaction could possibly explain the significance of neuroticism as a risk factor for suicide in women but not in men. High levels of openness together with high levels of neuroticism could be described as a personality style reflecting impulsive behavior and maladaptive, ineffective coping strategies [37,38,40]. These maladaptive strategies could help to explain greater suicide risk especially when combined with a tendency for negative affectivity (high levels of neuroticism).
In summary, the findings of this study highlight the role of personality dimensions as risk factors for suicide-related behaviors. Different personality dimensions are significantly associated with suicide-related behaviors even when adjusting for other known risk factors of suicidality. In the multidimensional diathesis-stress model of suicide , these personality features can be conceptualized as representing a trait-like vulnerability for suicide-related behaviors. While these personality factors are arguably of only marginal clinical utility in the assessment of acute suicidality, they may constitute an important component of a comprehensive evaluation of individuals at long-term risk of suicide-related behaviors . Since these personality dimensions are known to be rather stable over time, they underscore the necessity of more intensive psychological or psychotherapeutic treatments of at-risk individuals, e.g. by focusing on maladaptive coping strategies, which are characteristic for certain combinations of personality factors. These findings may also serve as a base for future research into neurobiological mechanisms underlying these relationships .
While a response rate of 58.3% is relatively high for a population-based survey, a possible bias of the respondents cannot be ruled out, which has to be taken into account when generalizing our findings. Due to time constraints in this population-based study, the short BFI-10 was used to assess personality, which does not allow a more in depths analysis of the facets that constitute the higher- order personality dimensions. Further research taking into account sex differences in the interaction between personality variables and suicide risk is warranted. Another limitation of this study is its reliance on self-reported suicidality, even though there is evidence that shows high-levels of agreement between self-report suicide assessment and face-to-face interviews . The respondents anonymously filled out the self-report suicide questionnaires and the interviewers did not read or evaluate the results. There is a risk that suicidal participants were not immediately identified and provided with professional support. Further research should consider this ethical issue in order to distinguish between the research participants’ right to privacy and uncovering suicide ideation among respondents . Researchers should carefully assess the value of anonymous answers versus the welfare of the participants. The SBQ-R is a well-validated and commonly used tool to assess suicidality. But the ability of the SBQ-R to predict future suicide attempts or completed suicide has not been established in prospective longitudinal studies yet. Finally, due to the cross-sectional design of this study, no causal conclusions can be inferred from the results. Longitudinal research into the association of personality characteristics and suicide risk with the inclusion of completed suicides is needed.
Conceived and designed the experiments: EB BW AK. Analyzed the data: VB NDK SD EB BW AK. Contributed reagents/materials/analysis tools: VB NDK. Wrote the manuscript: VB NDK SD.
- 1. Hawton K, van Heeringen K (2009) Suicide. Lancet 373: 1372-1381. doi:https://doi.org/10.1016/S0140-6736(09)60372-X. PubMed: 19376453.
- 2. Mann JJ, Apter A, Bertolote J, Beautrais A, Currier D et al. (2005) Suicide prevention strategies: a systematic review. JAMA 294: 2064-2074. doi:https://doi.org/10.1001/jama.294.16.2064. PubMed: 16249421.
- 3. Brezo J, Paris J, Turecki G (2006) Personality traits as correlates of suicidal ideation, suicide attempts, and suicide completions: a systematic review. Acta Psychiatr Scand 113: 180-206. doi:https://doi.org/10.1111/j.1600-0447.2005.00702.x. PubMed: 16466403.
- 4. Costa PT Jr, McCrae RR (1992) Normal Personality Assessment in Clinical Practice: The NEO Personality Inventory. Psychol Assess 4: 5-13. doi:https://doi.org/10.1037/1040-35188.8.131.52.
- 5. McCrae RR, Costa PT Jr (1987) Validation of the Five-Factor Model of Personality Across Instruments and Observers. J Pers Soc Psychol 52: 81-90. doi:https://doi.org/10.1037/0022-35184.108.40.206. PubMed: 3820081.
- 6. Jang KL, Livesley WJ, Vernon PA (1996) Heritability of the Big Five Personality Dimensions and Their Facets: A Twin Study. J Pers 64: 577-591. doi:https://doi.org/10.1111/j.1467-6494.1996.tb00522.x. PubMed: 8776880.
- 7. Terracciano A, Sanna S, Uda M, Deiana B, Usala G et al. (2010) Genome-wide association scan for five major dimensions of personality. Mol Psychiatry 15: 647-656. doi:https://doi.org/10.1038/mp.2008.113. PubMed: 18957941.
- 8. Hayward RD, Taylor WD, Smoski MJ, Steffens DC, Payne ME (2013) Association of five-factor model personality domains and facets with presence, onset, and treatment outcomes of major depression in older adults. Am J Geriatr Psychiatry 21: 88-96. doi:https://doi.org/10.1016/j.jagp.2012.12.114. PubMed: 23290206.
- 9. Koorevaar AML, Comijs HC, Dhondt ADF, van Marwijk HWJ, van der Mast RC et al. . (2013) Big Five personality and depression diagnosis, severity and age of onset in older adults. J Affect Disord (. (2013)) doi:https://doi.org/10.1016/j.jad.2013.05.075. PubMed: 23820093.
- 10. Kotov R, Gamez W, Schmidt F, Watson D (2010) Linking "Big" personality traits to anxiety, depressive, and substance use disorders: A meta-analysis. Psychol Bull 136: 768-821. doi:https://doi.org/10.1037/a0020327. PubMed: 20804236.
- 11. Weber K, Giannakopoulos P, Bacchetta JP, Quast S, Herrmann FR et al. (2012) Personality traits are associated with acute major depression across the age spectrum. Aging Ment Health 16: 472-480.
- 12. Heisel MJ, Duberstein PR, Conner KR, Franus N, Beckman A et al. (2006) Personality and reports of suicide ideation among depressed adults 50 years of age or older. J Affect Dis 90: 175-180. PubMed: 22128822.
- 13. Useda JD, Duberstein PR, Conner KR, Conwell Y (2004) Personality and attempted suicide in depressed adults 50 years of age and older: A facet level analysis. Compr Psychiatry 45: 353-361. doi:https://doi.org/10.1016/j.comppsych.2004.06.002. PubMed: 15332198.
- 14. Kerby DS (2003) CART analysis with unit-weighted regression to predict suicidal ideation from Big Five traits. Pers Individ Dif 35: 249-261. doi:https://doi.org/10.1016/S0191-8869(02)00174-5.
- 15. Chioqueta AP, Stiles TC (2005) Personality traits and the development of depression, hopelessness, and suicide ideation. Pers Individ Dif 38: 1283-1291. doi:https://doi.org/10.1016/j.paid.2004.08.010.
- 16. Rozanov VA, Mid’ko AA (2011) Personality patterns of suicide attempters: Gender differences in Ukraine. Span J Psychol 14: 693-700. doi:https://doi.org/10.5209/rev_SJOP.2011.v14.n2.17. PubMed: 22059315.
- 17. Velting DM (1999) Suicidal ideation and the five-factor model of personality. Pers Individ Dif 27: 943-952. doi:https://doi.org/10.1016/S0191-8869(99)00046-X.
- 18. Fang L, Heisel MJ, Duberstein PR, Zhang J (2012) Combined effects of neuroticism and extraversion: Findings from a matched case control study of suicide in Rural China. J Nerv Ment Dis 200: 598-602. doi:https://doi.org/10.1097/NMD.0b013e31825bfb53. PubMed: 22759937.
- 19. McCann SJH (2010) Suicide, big five personality factors, and depression at the american state level. Arch Suicide Res 14: 368-374. doi:https://doi.org/10.1080/13811118.2010.524070. PubMed: 21082452.
- 20. Voracek M (2009) Big five personality factors and suicide rates in the United States: A state-level analysis. Percept Mot Skills 109: 208-212. doi:https://doi.org/10.2466/pms.109.1.208-212. PubMed: 19831101.
- 21. Rammstedt B, John OP (2007) Measuring personality in one minute or less: A 10-item short version of the Big Five Inventory in English and German. J Res Pers 41: 203-212. doi:https://doi.org/10.1016/j.jrp.2006.02.001.
- 22. John OP, Donahue EM, Kentle RL (1991) The Big Five Inventory - Versions 4a and 54. Berkeley, CA: University of California, Berkeley, Institute of Personality and Social Research.
- 23. Löwe B, Decker O, Müller S, Brähler E, Schellberg D et al. (2008) Validation and standardization of the generalized anxiety disorder screener (GAD-7) in the general population. Med Care 46: 266-274. doi:https://doi.org/10.1097/MLR.0b013e318160d093. PubMed: 18388841.
- 24. Spitzer RL, Kroenke K, Williams JBW, Löwe B (2006) A brief measure for assessing generalized anxiety disorder: The GAD-7. Arch Intern Med 166: 1092-1097. doi:https://doi.org/10.1001/archinte.166.10.1092. PubMed: 16717171.
- 25. Kroenke K, Spitzer RL, Williams JBW, Monahan PO, Löwe B (2007) Anxiety disorders in primary care: Prevalence, impairment, comorbidity, and detection. Ann Intern Med 146: 317-325. doi:https://doi.org/10.7326/0003-4819-146-5-200703060-00004. PubMed: 17339617.
- 26. Löwe B, Spitzer RL, Zipfel S, Herzog W (2002) Gesundheitsfragebogen für Patienten (PHQ-D). Komplettversion und Kurzform. Authorized German version of the Prime MD Patient Health Questionnaire (PHQ). Karlsruhe: Pfizer Pharmaceuticals.
- 27. Spitzer RL, Williams JBW, Kroenke K, Linzer M, DeGruy FV iii et al. (1994) Utility of a new procedure for diagnosing mental disorders in primary care: The PRIME-MD 1000 study. JAMA 272: 1749-1756. doi:https://doi.org/10.1001/jama.272.22.1749. PubMed: 7966923.
- 28. Kroenke K, Spitzer RL, Williams JBW (2001) The PHQ-9: Validity of a brief depression severity measure. J Gen Intern Med 16: 606-613. doi:https://doi.org/10.1046/j.1525-1497.2001.016009606.x. PubMed: 11556941.
- 29. Spitzer RL, Kroenke K, Williams JBW (1999) Validation and utility of a self-report version of PRIME-MD: The PHQ Primary Care Study. JAMA 282: 1737-1744. doi:https://doi.org/10.1001/jama.282.18.1737. PubMed: 10568646.
- 30. Osman A, Bagge CL, Gutierrez PM, Konick LC, Kopper BA et al. (2001) The suicidal behaviors questionnaire-revised (SBQ-R): Validation with clinical and nonclinical samples. Assessment 8: 443-454. doi:https://doi.org/10.1177/107319110100800409. PubMed: 11785588.
- 31. Wagner B, Klinitzke G, Brähler E, Kersting A (2013) Extreme Obesity Is Associated with Suicidal Behavior and Suicide Attempts in Adults: Results of a Population-Based Representative Sample. Depress Anxiety 2013. doi:https://doi.org/10.1002/da.2210532. PubMed: 23576272;
- 32. Forkmann T, Brähler E, Gauggel S, Glaesmer H (2012) Prevalence of suicidal ideation and related risk factors in the German general population. J Nerv Ment Dis 200: 401-405. doi:https://doi.org/10.1097/NMD.0b013e31825322cf. PubMed: 22551793.
- 33. Bernal M, Haro JM, Bernert S, Brugha T, de Graaf R et al. (2007) Risk factors for suicidality in Europe: Results from the ESEMED study. J Affect Disord 101: 27-34. doi:https://doi.org/10.1016/j.jad.2006.09.018. PubMed: 17074395.
- 34. DeNeve KM, Cooper H (1998) The Happy Personality: A Meta-Analysis of 137 Personality Traits and Subjective Well-Being. Psychol Bull 124: 197-229. doi:https://doi.org/10.1037/0033-2909.124.2.197. PubMed: 9747186.
- 35. Gunthert KC, Cohen LH, Armeli S (1999) The role of neuroticism in daily stress and coping. J Pers Soc Psychol 77: 1087-1100. doi:https://doi.org/10.1037/0022-35220.127.116.117. PubMed: 10573882.
- 36. Duberstein PR, Conner KR, Conwell Y, Cox C (2001) Personality correlates of hopelessness in depressed inpatients 50 years of age and older. J Pers Assess 77: 380-390. doi:https://doi.org/10.1207/S15327752JPA7702_16. PubMed: 11693865.
- 37. Piedmont RL, Sherman MF, Sherman NC (2012) Maladaptively High and Low Openness: The Case for Experiential Permeability. J Pers 80: 1641-1668. doi:https://doi.org/10.1111/j.1467-6494.2012.00777.x. PubMed: 22320184.
- 38. Piedmont RL, Sherman MF, Sherman NC, Dy-Liacco GS, Williams JEG (2009) Using the Five-Factor Model to Identify a New Personality Disorder Domain: The Case for Experiential Permeability. J Pers Soc Psychol 96: 1245-1258. doi:https://doi.org/10.1037/a0015368. PubMed: 19469599.
- 39. Manuck SB, Flory JD, McCaffery JM, Matthews KA, Mann JJ et al. (1998) Aggression, impulsivity, and central nervous system serotonergic responsivity in a nonpatient sample. Neuropsychopharmacology 19: 287-299. doi:https://doi.org/10.1038/sj.npp.1395199. PubMed: 9718592.
- 40. Watson D, Hubbard B (1996) Adaptational Style and Dispositional Structure: Coping in the Context of the Five-Factor Model. J Pers 64: 736-774.
- 41. Hawton K, Casañas I, Comabella C, Haw C, Saunders K (2013) Risk factors for suicide in individuals with depression: A systematic review. J Affect Disord 147: 17-28. doi:https://doi.org/10.1016/j.jad.2013.01.004. PubMed: 23411024.
- 42. Hawton K (2000) Sex and suicide: Gender differences in suicidal behaviour. Br J Psychiatry 177: 484-485. doi:https://doi.org/10.1192/bjp.177.6.484. PubMed: 11102320.
- 43. Mościcki EK (1994) Gender differences in completed and attempted suicides. Ann Epidemiol 4: 152-158. doi:https://doi.org/10.1016/1047-2797(94)90062-0. PubMed: 8205283.
- 44. Schmidtke A, Bille-Brahe U, DeLeo D, Kerkhof A, Bjerke T et al. (1996) Attempted suicide in Europe: Rates, trends and sociodemographic characteristics of suicide attempters during the period 1989-1992. Results of the WHO/EURO Multicentre Study on Parasuicide. Acta Psychiatr Scand 93: 327-338. doi:https://doi.org/10.1111/j.1600-0447.1996.tb10656.x. PubMed: 8792901.
- 45. Sareen J, Cox BJ, Afifi TO, De Graaf R, Asmundson GJG et al. (2005) Anxiety disorders and risk for suicidal ideation and suicide attempts: A population-based longitudinal study of adults. Arch Gen Psychiatry 62: 1249-1257. doi:https://doi.org/10.1001/archpsyc.62.11.1249. PubMed: 16275812.
- 46. Cougle JR, Keough ME, Riccardi CJ, Sachs-Ericsson N (2009) Anxiety disorders and suicidality in the National Comorbidity Survey-Replication. J Psychiatr Res 43: 825-829. doi:https://doi.org/10.1016/j.jpsychires.2008.12.004. PubMed: 19147159.
- 47. Kendler KS, Neale MC, Kessler RC, Heath AC, Eaves LJ (1993) A longitudinal twin study of personality and major depression in women. Arch Gen Psychiatry 50: 853-862. doi:https://doi.org/10.1001/archpsyc.1993.01820230023002. PubMed: 8215811.
- 48. Kendler KS, Kuhn J, Prescott CA (2004) The Interrelationship of Neuroticism, Sex, and Stressful Life Events in the Prediction of Episodes of Major Depression. Am J Psychiatry 161: 631-636. doi:https://doi.org/10.1176/appi.ajp.161.4.631. PubMed: 15056508.
- 49. Johnson WB, Lall R, Bongar B, Nordlund MD (1999) The role of objective personality inventories in suicide risk assessment: An evaluation and proposal. Suicide Life Threat Behav 29: 165-185. PubMed: 10407969.
- 50. Bjørnebekk A, Fjell AM, Walhovd KB, Grydeland H, Torgersen S et al. (2013) Neuronal correlates of the five factor model (FFM) of human personality: Multimodal imaging in a large healthy sample. NeuroImage 65: 194-208. doi:https://doi.org/10.1016/j.neuroimage.2012.10.009. PubMed: 23063449.
- 51. Kaplan ML, Asnis GM, Sanderson WC, Keswani L, De Lecuona JM et al. (1994) Suicide assessment: Clinical interview vs. self-report. J Clin Psychol 50: 294-298. doi:https://doi.org/10.1002/1097-4679(199403)50:2. PubMed: 8014256.
- 52. Wilson CM, Christensen BK (2012) Ethical issues relevant to the assessment of suicide risk in nonclinical research settings. Crisis 33: 54-59. PubMed: 21945844.