Age changes in personality traits and their heritabilities during the adult years: evidence from Australian twin registry samples

Trajectories and determinants of acute stress disorder during the COVID-19 centralized quarantine: A latent class growth analysis

COVID-19 centralized quarantine may cause acute stress disorder (ASD). However, it is unknown how individuals present heterogeneous ASD trajectories during the COVID-19 centralized quarantine and what factors contribute to these patterns. This study aimed to identify the ASD trajectories and their determinants during the centralized quarantine period, and the mediating effects of resilience on these associations. A longitudinal survey with three waves was conducted in a randomly selected quarantine hotel in Shenzhen, China from October to November 2020. A total of 273 participants completed online measures assessing ASD symptoms, Eysenck's personality constructs of extraversion (E), neuroticism (N), psychoticism (P), and resilience on Day 1, and reported ASD symptoms on Days 7 and 14 during their 14-day centralized quarantine periods. Latent class growth analysis identified three trajectories: constantly high symptoms (CHS, 4.76%), decreasing symptoms (DS, 11.72%), and constantly low symptoms (CLS, 83.52%). The CHS and DS subgroups both reported lower E and higher N scores, but not P, compared with the CLS subgroup. Resilience mediated the effects of three personality constructs on ASD trajectories, except for the association between N and DS membership. Our study highlights the heterogeneity in stress responses to the COVID-19 centralized quarantine. The high-risk subgroup with persistent ASD symptoms was characterized by lower E and higher N. The resilience process accounted for the effects of personality in shaping distinct ASD trajectories. Our findings have implications to detect the populations vulnerable to ASD and provide insights for developing timely resilience enhancement intervention programs.

Extraversion and Neuroticism as antecedents of emotion regulation and dysregulation in adulthood

This longitudinal study examined the role of Extraversion and Neuroticism as antecedents of emotion regulation and dysregulation among 89 women and 81 men. When participants were 27 years old, their Extraversion and Neuroticism were assessed with the standardized version of the Eysenck Personality Questionnaire. At age 33, they completed the Big‐Five Personality Inventory, an authorized adaptation of the NEO Personality Inventory. Emotion regulation, operationalized as an active attempt to turn a negative emotion toward a more positive direction, and measured by the Repair subscale of the Meta‐Regulation Scale, and emotional social support, as measured by the Life Situation Questionnaire, were assessed when participants reached 36 years of age. Emotional ambivalence, a type of emotion dysregulation, was also assessed in this wave. Structural equation modelling demonstrated that prior Neuroticism led to higher emotional ambivalence and lowered use of Repair at age 36. Prior Extraversion, on the other hand, was linked to lower emotional ambivalence at age 36. Extraversion also led to higher attempts to rely on emotional social support to regulate emotions, but less interest in using Repair. Correlational findings revealed that Extraversion and Neuroticism showed differential continuity between ages 27 and 33. Copyright © 2001 John Wiley & Sons, Ltd.

Construct validation using multitrait‐multimethod‐twin data: The case of a general factor of personality

We describe a behavioural genetic extension of the classic multitrait‐multimethod study design that allows estimating genetic and environmental influences on method effects in twin studies (MTMM‐T). Genetic effects and effects of the environment shared by siblings are interpreted as indicators of convergent validity. In an application of the MTMM study design, we used self‐ and peer report data to examine the higher‐order structure of the NEO‐PI‐R. Structural equation modelling did not support a general factor of personality in multimethod data. The higher‐order factor Stability turns out to be, at most, a weak trait factor. Genetic effects on method factors indicate that especially self‐reports but also peer reports show convergent validity between twins but not between methods. Copyright © 2010 John Wiley & Sons, Ltd.

GHQ score changes from teenage to young adulthood

This study investigated the change in the General Health Questionnaire (GHQ-12) scores from teenage years to young adulthood using a large, nationally representative sample in the UK. It took account of socio-demographic variables, childhood intelligence, behavioural problems and self-esteem at teenage and educational qualifications in early adulthood. In total, 3942 cohort members had the complete data on GHQ at ages 16 and 30 years. T-tests showed that there was statistically significant increase of GHQ mean scores over the 14 years (p < .001), however at the item level there were changes in both directions. The analysis showed that over 14 years the test-retest correlation was r = 0.24, indicating a modest level of stability. The GHQ was significantly and negatively associated with self-esteem, and positively associated with childhood behavioural problems. Regression analysis showed that gender, self-esteem, and behavioural problems measured in the teenage years were all significant predictors of GHQ at both time points, indicating the long-term effects of psychological and behavioural factors on teenagers and young adults' mental health outcome. The implications for early interventions in school and family settings are discussed.

Neuroticism and extraversion mediate the association between loneliness and the dorsolateral prefrontal cortex

Loneliness is an unpleasant and distressing feeling that a person experiences when he/she perceives that his/her social relationships are lacking in someway, either quantitatively or qualitatively; this can be linked to anxiety, depression, and suicide risk. Previous studies have found that certain personality traits (which are temporally stable and heritable) are predictors of loneliness. However, little empirical evidence is available on the brain structures associated with loneliness, as well as how personality traits impact the relationship between loneliness and brain structure. Thus, the current study used voxel-based morphometry to identify the brain structures underlying individual differences in loneliness (as measured by the UCLA Loneliness Scale) in a large sample, and then, applied multiple mediation analyses to explore the nature of the influence of personality traits on the relationship between loneliness and brain structure. The results showed that lonely individuals had greater regional gray matter volume in the left dorsolateral prefrontal cortex (DLPFC), which might reflect immature functioning in terms of emotional regulation. More importantly, we found that neuroticism and extraversion partially mediated the relationship between the left DLPFC and loneliness. In summary, through morphometric and multiple mediation analyses, this paper further validates the influence of both neuroticism and extraversion on loneliness.

The Behavioural Genetics of Personality Development in Adulthood—Classic, Contemporary, and Future Trends

Behavioural genetic research has led to important advances in the field of personality psychology. When carried out on longitudinal data, behavioural genetic studies also offer promising ways to examine the genetic and environmental origins of personality stability and change. Here, we review the findings of longitudinal twin studies, discuss their implications for our understanding of adult personality development, and point out open questions that need to be addressed by future research. Three general conclusions stand out. First, there is a strong and relatively stable genetic foundation of individual differences in personality throughout the adult life span; second, environmental influences become more important and contribute to an increasing rank–order stability of personality traits from early to middle adulthood; and third, both genetic and nonshared environmental influences contribute to both stability and change in personality traits. Equipped with this knowledge, the most urgent tasks for the next generation of behavioural genetic studies on personality development will be to (i) identify measurable environmental factors that matter and (ii) to capture the interplay between genetic and environmental influences on personality stability and change throughout adulthood. Copyright © 2014 European Association of Personality Psychology

Does human presynaptic striatal dopamine function predict social conformity?

Socially desirable responding (SDR) is a personality trait which reflects either a tendency to present oneself in an overly positive manner to others, consistent with social conformity (impression management (IM)), or the tendency to view one's own behaviour in an overly positive light (self-deceptive enhancement (SDE)). Neurochemical imaging studies report an inverse relationship between SDR and dorsal striatal dopamine D₂/₃ receptor availability. This may reflect an association between SDR and D₂/₃ receptor expression, synaptic dopamine levels or a combination of the two. In this study, we used a [¹⁸F]-DOPA positron emission tomography (PET) image database to investigate whether SDR is associated with presynaptic dopamine function. Striatal [¹⁸F]-DOPA uptake, (k(i)(cer), min⁻¹), was determined in two independent healthy participant cohorts (n=27 and 19), by Patlak analysis using a cerebellar reference region. SDR was assessed using the revised Eysenck Personality Questionnaire (EPQ-R) Lie scale, and IM and SDE were measured using the Paulhus Deception Scales. No significant associations were detected between Lie, SDE or IM scores and striatal [¹⁸F]-DOPA k(i)(cer). These results indicate that presynaptic striatal dopamine function is not associated with social conformity and suggests that social conformity may be associated with striatal D₂/₃ receptor expression rather than with synaptic dopamine levels.

The big five personality traits: psychological entities or statistical constructs?

The present study employed multivariate genetic item-level analyses to examine the ontology and the genetic and environmental etiology of the Big Five personality dimensions, as measured by the NEO Five Factor Inventory (NEO-FFI) [Costa and McCrae, Revised NEO personality inventory (NEO PI-R) and NEO five-factor inventory (NEO-FFI) professional manual, 1992; Hoekstra et al., NEO personality questionnaires NEO-PI-R, NEO-FFI: manual, 1996]. Common and independent pathway model comparison was used to test whether the five personality dimensions fully mediate the genetic and environmental effects on the items, as would be expected under the realist interpretation of the Big Five. In addition, the dimensionalities of the latent genetic and environmental structures were examined. Item scores of a population-based sample of 7,900 adult twins (including 2,805 complete twin pairs; 1,528 MZ and 1,277 DZ) on the Dutch version of the NEO-FFI were analyzed. Although both the genetic and the environmental covariance components display a 5-factor structure, applications of common and independent pathway modeling showed that they do not comply with the collinearity constraints entailed in the common pathway model. Implications for the substantive interpretation of the Big Five are discussed.

Nature and Nurture in Personality Development

The stability of interindividual differences (i.e., rank-order continuity) in personality traits tends to increase with age until it plateaus in middle adulthood and finally decreases in old age. Rank-order continuity also tends to decrease as the time intervals between occasions of personality assessment increase, irrespective of age. These patterns show that personality development is a lifelong process. Yet the sources of these patterns are unknown. Theories suggest that personality continuity and change may result from environmentally mediated processes of identity development due to age-graded social roles and individual life experiences, but also from biological maturation. Genetically informative longitudinal studies across different age cohorts allow a differentiated picture of genetic and environmental sources. In this article, I give a short overview of the genetic and environmental contributions to rank-order continuity and change in neuroticism and extraversion. Both genetic and environmental factors contribute to personality continuity and change, but genetic factors affect rank-order change only in younger decades of life, whereas environmental influences appear to represent a lifelong source of interindividual differences in personality development.

Stability of Genetic and Environmental Effects from Adolescence to Young Adulthood: Results of Croatian Longitudinal Twin Study of Personality

The primary aim of this study was to conduct a bivariate genetic analysis investigating the extent to which genetic and environmental factors contribute to stability and change in personality factors in the period from adolescence to young adulthood on a sample of Croatian twins. The sample used in this research was formed in 1992 based on a register of citizens of Zagreb and data was collected for 160 twin pairs (75 monozygotic and 85 dizygotic twin pairs). Twins were tested twice, 4 years apart with the Eysenck Personality Questionnaire (mean age at first time point was 17 years). Univariate analyses indicate that the best fitting model for extraversion, neuroticism, psychoticism and lie scale at both time points includes additive genetic (A) and nonshared environmental (E) influences, with heritability estimates in the .40 to .50 range. Longitudinal analyses using AE correlated factors model indicate that genetic factors contribute mainly to stability, while environmental factors contribute mainly to change in personality during that 4-year period of transition from adolescence to young adulthood.

Genetic and environmental influences on impulsivity: a meta-analysis of twin, family and adoption studies

A meta-analysis of twin, family and adoption studies was conducted to estimate the magnitude of genetic and environmental influences on impulsivity. The best fitting model for 41 key studies (58 independent samples from 14 month old infants to adults; N=27,147) included equal proportions of variance due to genetic (0.50) and non-shared environmental (0.50) influences, with genetic effects being both additive (0.38) and non-additive (0.12). Shared environmental effects were unimportant in explaining individual differences in impulsivity. Age, sex, and study design (twin vs. adoption) were all significant moderators of the magnitude of genetic and environmental influences on impulsivity. The relative contribution of genetic effects (broad sense heritability) and unique environmental effects were also found to be important throughout development from childhood to adulthood. Total genetic effects were found to be important for all ages, but appeared to be strongest in children. Analyses also demonstrated that genetic effects appeared to be stronger in males than in females. Method of assessment (laboratory tasks vs. questionnaires), however, was not a significant moderator of the genetic and environmental influences on impulsivity. These results provide a structured synthesis of existing behavior genetic studies on impulsivity by providing a clearer understanding of the relative genetic and environmental contributions in impulsive traits through various stages of development.

Sexual orientation and psychiatric vulnerability: a twin study of neuroticism and psychoticism

Recent evidence indicates that homosexuals and bisexuals are, on average, at greater risk for psychiatric problems than heterosexuals. It is assumed with some supporting evidence that prejudice often experienced by nonheterosexuals makes them more vulnerable to psychiatric disorder, but there has been no investigation of alternative explanations. Here we used Eysenck's Neuroticism and Psychoticism scales as markers for psychiatric vulnerability and compared heterosexuals with nonheterosexuals in a community-based sample of identical and nonidentical twins aged between 19 and 52 years (N = 4904). Firstly, we tested whether apparent sexual orientation differences in psychiatric vulnerability simply mirrored sex differences-for our traits, this would predict nonheterosexual males having elevated Neuroticism scores as females do, and nonheterosexual females having elevated Psychoticism scores as males do. Our results contradicted this idea, with nonheterosexual men and women scoring significantly higher on Neuroticism and Psychoticism than their heterosexual counterparts, suggesting an overall elevation of psychiatric risk in nonheterosexuals. Secondly, we used our genetically informative sample to assess the viability of explanations invoking a common cause of both nonheterosexuality and psychiatric vulnerability. We found significant genetic correlation between sexual orientation and both Neuroticism and Psychoticism, but no corresponding environmental correlations, suggesting that if there is a common cause of both nonheterosexuality and psychiatric vulnerability it is likely to have a genetic basis rather than an environmental basis.

Variation in DRD2 dopamine gene predicts Extraverted personality

Quantitative geneticists estimate the heritability of Extraverted personality to be around 40-60%. Theory and research which links Extraversion with variation in dopaminergic function suggests that dopaminergic genes should be a start-point for molecular genetic investigations of this trait. Recent endeavours in this area have met with some encouragement but also setbacks. In this study, we investigate the relationship between Extraversion and the DRD2 TaqIA/ANKK1 polymorphism in 224 university students. Presence of at least one copy of the A1 allele was associated with significantly higher Extraversion. The robustness of this finding was confirmed through bootstrap analysis. Findings are discussed in relation to the broader literature, in particular, methodological issues which may have obscured this finding in previous research.

Are there shared environmental influences on adolescent behavior? Evidence from a study of adoptive siblings

The failure to identify specific non-shared environmental influences on behavior coupled with the belief that shared environmental factors contribute minimally to individual differences in behavior has led to the concern that major environmental determinants of behavior may be idiosyncratic, and therefore undetectable. We used data on adoptive (N = 246) and biologically related (N = 130) same-sex sibling pairs (mean ages = 16.1 years older sibling; 13.8 years younger sibling) from the Sibling Interaction and Behavior Study (SIBS) to determine whether non-idiosyncratic environmental factors shared by siblings contributed to individual differences in a diverse set of behavioral outcomes. Evidence for shared environmental influence was sought for eight composite measures covering a wide array of adolescent functioning: Academic Achievement, Total IQ, Substance Use Disorders, Externalizing Disorders, Internalizing Disorders, Peer Groups, Disinhibited Personality, and Negative Emotionality. For six of eight composites, significant shared environmental effects, accounting for 14-22% of the variance, were observed for these same-sex sibling pairs. These findings support the use of adoptive sibling designs to directly estimate shared environmental effects and implicate the existence of systematic environmental influences on behavior that are potentially detectable.

Personal Goals of Older Female Twins

This study examined genetic and environmental influences on older women’s personal goals by using data from the Finnish Twin Study on Aging. The interview for the personal goals was completed by 67 monozygotic (MZ) pairs and 75 dizygotic (DZ) pairs. The tetrachoric correlations for personal goals related to health and functioning, close relationships, and independent living were higher in MZ than DZ twins, indicating possible genetic influence. The pattern of tetrachoric correlations for personal goals related to cultural activities, care of others, and physical exercise indicated environmental influence. For goals concerning health and functioning, independent living, and close relationships, additive genetic effect accounted for about half of the individual variation. The rest was the result of a unique environmental effect. Goals concerning physical exercise and care of others showed moderate common environmental effect, while the rest of the variance was the result of a unique environmental effect. Personal goals concerning cultural activities showed unique environmental effects only.

Marriage and Genetic Variation across the Lifespan: Not a Steady Relationship?

The prevalence of marriage varies across the lifespan, as does its importance to reproduction and the nurturance of children. We examined genetic and environmental influences on self-reported marriage at each decade from 20 through 70 years of age, using data collected for the Duke Dementia Study, a followed-up subset of the World War II Veteran Twin Registry. Genetic influences best fit a common factor model, supplemented by another, age-specific, genetic factor at age 30. Broad heritability increased from age 20 through 40, and then decreased to zero by ages 60 and 70. A longitudinal Cholesky model best described environmental influences on marriage across the lifespan. Shared environmental factors showed their greatest influence at age 20, no influence at 30 or 40 years, and then, reappeared with influence at 60 and 70. Variance due to error and unique environmental influences increased steadily to age 50 years and then declined slightly.

Sensational Interests, Mating Effort, and Personality: Evidence for Cross-Cultural Validity

Abstract. We assessed whether violent or macabre interests (“sensational interests”) were related to mating effort and a higher-order personality construct reflecting the combined features of higher Extraversion, lower Psychoticism, and lower Neuroticism in 1321 participants from English-speaking (Tucson, Arizona, and Glasgow, Scotland) and Spanish-speaking (Hermosillo, Mexico, and Talca, Chile) communities. Participants from Spanish-speaking communities generally had more sensational interests. Mating effort was positively related to sensational interests, though the relationship was slightly weaker in Spanish-speaking communities. Personality effects were modest and entirely moderated by language; personality was negatively related to sensational interests in English-speaking communities, but positively associated to sensational interests in Spanish-speaking communities. These findings suggest that the relationship between mating effort and sensational interests is universal and reflects general intrasexual competition, whereas the relationship between personality and sensational interests is more culture-specific.

Words of wisdom: language use over the life span

Two projects explored the links between language use and aging. In the first project, written or spoken text samples from disclosure studies from over 3,000 research participants from 45 different studies representing 21 laboratories in 3 countries were analyzed to determine how people change in their use of 14 text dimensions as a function of age. A separate project analyzed the collected works of 10 well-known novelists, playwrights, and poets who lived over the last 500 years. Both projects found that with increasing age, individuals use more positive and fewer negative affect words, use fewer self-references, use more future-tense and fewer past-tense verbs, and demonstrate a general pattern of increasing cognitive complexity. Implications for using language as a marker of personality among current and historical texts are discussed.

Happiness and Health: Environmental and Genetic Contributions to the Relationship Between Subjective Well-Being, Perceived Health, and Somatic Illness

The aim was to identify genetic and environmental influences on the covariances between subjective well-being (SWB), perceived health, and somatic illness. Analyses were based on 6576 Norwegian twins aged 18-31. Heritabilities ranged from .24 to.66. SWB correlated .50 with perceived health, -.25 with musculoskeletal pain, and -.07 with allergy. Common genetic factors accounted for 45%-60% of associations. SWB and perceived health was to a high extent influenced by the same genes (r(g)=.72 and.82 for males and females, respectively). For SWB and musculoskeletal pain, r-sub(g) =-.29 and -.42 for males and females, respectively. Effects were partly sex specific. Environmental factors shared by twins did not affect the covariances. Results support a differentiated view of SWB-health relations, and imply that both genes and environment play important roles in the associations between well-being and health.