Agentive steadfastness as trait marker in relation to temperament and character

BACKGROUND

Agentive steadfastness was identified as a potential trait marker with which to anticipate prognostically that a patient will persevere steadfastly and take congruent action in facing the demands of living. Taken as an enduring expression of personality, this study investigated agentive steadfastness among adult social media respondents (n = 511) in relation to temperament and character as captured in Cloninger's psychobiological model of personality.

METHODS

Participants recruited though snowball sampling on social media platforms, applied the 27-item Agentive Steadfastness Index (ASI) and the 240-item Temperament and Character Inventory (TCI-R-240).

RESULTS

Agentive steadfastness was statistically predicted by the Self-directedness (β = 0.634), Self-transcendence (β = 0.119), Harm Avoidance (β = -0.142) and the Reward Dependence (β = 0.071) scales, accounting for 63.3 % of the variance in one stepwise regression model. In another stepwise model for the TCI-R-240 subscales, the Purposeful (β = 0.359), Anticipatory Worry (β = -0.353), and the Responsibility (β = 0.259) subscales accounted for respectively 56.8 %, 11.2 % and 2.8 % of the variance in ASI scores.

LIMITATIONS

Results are limited to adult social media respondents who were willing to participate.

CONCLUSIONS

Agentive steadfastness may serve as a trait marker of well-being and the good prognostic associations that have been established for high self-directedness, low harm avoidance, as well as resilience, and character strengths. It may be assessed clinically to anticipate prognostically the extent to which a patient will persevere steadfastly and take congruent action in facing the demands of living and adversity.

Associations between affective temperament, perceived stress, and helping among Ukrainians and Poles in the context of the war in Ukraine

The Russian aggression of Ukraine has put millions of civilians under immense stress and forced many of them to leave their homes for safety and help. Poland became one of the leading destinations for waves of Ukrainians fleeing this war. The level of perceived stress in people who experienced war depends on various factors, including individual psychological variables. The main aim of this study was to analyze perceived stress levels and the predictive role of affective temperaments, as defined by Akiskal, for perceived stress in Ukrainians and Poles during the first year of the Russo-Ukrainian war. Secondly, we studied the relationship between affective temperament, stress, and commitment to help Ukrainian refugees. Self-report data from 410 Ukrainians and 146 Poles were collected. The results of this study shed light on perceived stress in war-affected populations and the role of affective temperaments in predicting its levels. We also demonstrated the links between affective temperament, perceived stress, and involvement in helping Ukrainian refugees. Understanding the mental status of people affected by war and its predictors is crucial to providing appropriate support and assistance to those in need.

Associations of lipids in adolescence and adulthood with self- and other-directed compassion in adulthood

Self- and other-directed compassion have been linked with better mental and physical health but research on factors contributing to their development is scarce. Previous studies indicate a possible causal relationship of lipids with personality and socioemotional functioning. As an extension to earlier research, in the present study we examine whether lipids assessed in adolescence and adulthood are associated with self-compassion and other-directed compassion in adulthood. The study utilizes data on lipids from two follow-ups in the Northern Finland Birth Cohort 1986 at ages 15-16 and 33-35. In the latter follow-up also self-compassion and other-directed compassion were assessed with the self-compassion scale - short form and the subscale for compassion in the dispositional positive emotions scale, respectively. The sample for the cross-sectional associations of lipids in adulthood with the compassion variables in adulthood includes 1,459 participants, whereas the sample for the longitudinal associations of lipids in adolescence and the compassion variables in adulthood consists of 1,509 participants. The associations were examined with hierarchical linear regression (lipids as continuous variables) and univariate general linear model (lipids as categorical variables). The results suggest that in women, high-density lipoprotein (HDL) cholesterol in adolescence is associated with high empathic concern (a component of other-directed compassion) in adulthood. The results show further that, in women, an HDL cholesterol level above 1.2 mmol/L in adulthood is associated with high other-directed compassion and empathic concern in adulthood. The present study provides tentative evidence that biological factors such as lipids might play a role in the development of empathic concern and other-directed compassion.

Meta-Analytic Review of Temperamental Correlates of the Five-Factor Model and Hierarchical Taxonomy of Psychopathology Domains

Background

There is little and heterogeneous knowledge on the links between the temperamental predispositions of psychopathology and the contemporary dimensional models of psychopathology, such as the Hierarchical Taxonomy of Psychopathology (HiTOP) classification system, which can be aligned with the five-factor model (FFM) of personality. This meta-analysis seeks to expand the temperamental theoretical basis of the HiTOP model by incorporating associations of temperament traits of two temperamental theories measured, respectively, by the Temperament and Character Inventory (TCI) and the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego Autoquestionnaire (TEMPS-A) with (a) the FFM's personality domains and (b) HiTOP's five psychopathological spectra.

Methods

A systematic search was done on Web of Science, Scopus, PubMed, ProQuest, Cochrane Database, and Google Scholar for all articles published in English from January 1990 to August 2020. Because of heterogeneity in the results of almost 70% of studies, pooled estimates of correlation coefficients were calculated using the random-effects method. Risk of bias (low-quality studies) and publication bias are reported.

Results

The pooled correlations obtained from the analysis of 35 studies showed that the temperamental profile associated with each FFM domain and HiTOP spectra is distinct. Specifically, TCI-harm avoidance (HA) and all TEMPS temperaments were more strongly related to neuroticism/internalizing, extraversion/low detachment, and conscientiousness/disinhibition. In contrast, TCI-novelty seeking was more strongly related to both disinhibited/antagonistic externalizing and thought disorder.

Conclusions

A large body of research supports maladaptive variants of all FFM domains and some psychopathological spectra of HiTOP related to the abnormal-range temperaments.

Personality dimensions and treatment adherence among glaucoma patients: the role of self-transcendence

BACKGROUND

Cloninger's psychobiosocial model of personality proposes that consistent patterns of health behavior are determined by the complex interaction of different neurobiological processes of the patient's temperament and character dimensions. Poor medication adherence is a pervasive problem among glaucoma patients and can lead to increased morbidity and disability. The objective of the present study was to investigate the association between Cloninger's personality dimensions and medication adherence among glaucoma patients.

METHODS

The cross-sectional study was conducted among 113 primary open-angle glaucoma (POAG) patients. The treatment adherence was assessed through a valid and reliable self-administered questionnaire, the Culig Adherence Scale (CAS). Personality dimensions were evaluated using the abbreviated version of the Temperament and Character Inventory-Revised (TCI-140). Statistical analyses were performed using TIBCO Statistica 14.0.1. The study protocol was registered in the DRKS - German Clinical Trials Register; (DRKS-ID: DRKS00022081).

RESULTS

According to CAS, only 39.8% of patients were adherent to glaucoma treatment. Adherence was significantly negatively related only to the character dimension of Self-Transcendence (p < 0.05). No other TCI-140 dimension was significantly associated with medication adherence (p > 0.05).

CONCLUSIONS

The results suggest that POAG patients with higher scores on the Self-Transcendent personality dimension are more likely to experience difficulties adhering to medication regimen. The study highlights the importance of a holistic approach to glaucoma treatment, which takes into account not only the biological aspects of disease but also the psychosocial factors that influence patient behavior. Healthcare providers may need to consider glaucoma patients' personality dimensions, beliefs and values when developing treatment plans and strategies to improve medication adherence.

Integrating trauma, self-disturbances, cognitive biases, and personality into a model for the risk of psychosis: a longitudinal study in a non-clinical sample

The hypothesis of the psychosis continuum enables to study the mechanisms of psychosis risk not only in clinical samples but in non-clinical as well. The aim of this longitudinal study was to investigate self-disturbances (SD), a risk factor that has attracted substantial interest over the last two decades, in combination with trauma, cognitive biases and personality, and to test whether SD are associated with subclinical positive symptoms (PS) over a 12-month follow-up period. Our study was conducted in a non-clinical sample of 139 Polish young adults (81 females, age M = 25.32, SD = 4.51) who were selected for frequent experience of subclinical PS. Participants completed self-report questionnaires for the evaluation of SD (IPASE), trauma (CECA.Q), cognitive biases (DACOBS) and personality (TCI), and were interviewed for subclinical PS (CAARMS). SD and subclinical PS were re-assessed 12 months after baseline measurement. The hypothesized model for psychosis risk was tested using path analysis. The change in SD and subclinical PS over the 12-month period was investigated with non-parametric equivalent of dependent sample t-tests. The models with self-transcendence (ST) and harm avoidance (HA) as personality variables were found to be well-fitted and explained 34% of the variance in subclinical PS at follow-up. Moreover, we found a significant reduction of SD and subclinical PS after 12 months. Our study suggests that combining trauma, cognitive biases, SD and personality traits such as ST and HA into one model can enhance our understanding of appearance as well as maintenance of subclinical PS.

Genetic differential susceptibility to the parent-child relationship quality and the life span development of compassion

The development of compassion for others might be influenced by the social experiences made during childhood and has a genetic component. No research has yet investigated whether the parent-child relationship quality interacts with genetic variation in the oxytocin and dopamine systems in predicting compassion over the life span. In the prospective Young Finns Study (N = 2099, 43.9% men), we examined the interaction between mother-reported emotional warmth and intolerance toward their child assessed in 1980 (age of participants, 3-18 years) and two established genetic risk scores for oxytocin levels and dopamine signaling activity. Dispositional compassion for others was measured with the Temperament and Character Inventory 1997, 2001, and 2012 (age of participants, 20-50 years). We found a gene-environment interaction (p = .031) that remained marginally significant after adjustment for multiple testing. In line with the differential susceptibility hypothesis, only participants who carry alleles associated with low dopamine signaling activity had higher levels of compassion when growing up with emotionally warm parents, whereas they had lower levels of compassion when their parents were emotionally cold. Children's genetic variability in the dopamine system might result in plasticity to early environmental influences that have a long-lasting effect on the development of compassion. However, our findings need replication.

Functional Polymorphisms in Oxytocin and Dopamine Pathway Genes and the Development of Dispositional Compassion Over Time: The Young Finns Study

Background: We define compassion as an enduring disposition that centers upon empathetic concern for another person's suffering and the motivation to act to alleviate it. The contribution of specific candidate genes to the development of dispositional compassion for others is currently unknown. We examine candidate genes in the oxytocin and dopamine signaling pathways.

Methods: In a 32-year follow-up of the Young Finns Study (N = 2,130, 44.0% men), we examined with multiple indicators latent growth curve modeling the molecular genetic underpinnings of dispositional compassion for others across the life span. We selected five single nucleotide polymorphisms (SNPs) whose functions are known in humans: rs2268498 (OXTR), rs3796863 (CD38) (related to lower oxytocin levels), rs1800497 (ANKK1/DRD2), rs4680 (COMT), and rs1611115 (DBH) (related to higher dopamine levels). Compassion was measured with Cloninger's Temperament and Character Inventory on three repeated observations spanning 15 years (1997–2012). Differences between gender were tested.

Results: We did not find an effect of the five SNPs in oxytocin and dopamine pathway genes on the initial levels of dispositional compassion for others. Individuals who carry one or two copies of the T-allele of DBH rs1611115, however, tend to increase faster in compassion over time than those homozygotes for the C-allele, b = 0.063 (SE = 0.027; p = 0.018). This effect was largely driven by male participants, 0.206 (SE = 0.046; p < 0.001), and was not significant in female participants when analyzed separately.

Conclusions: Men who are known to have, on average, lower compassion than women seem to reduce this difference over time if they carry the T-allele of DBH rs1611115. The direction of the association indicates that dopamine signaling activity rather than overall dopamine levels might drive the development of compassion.

Genetic and environmental architecture of conscientiousness in adolescence

Using a genetically informative design (about 2000 twin pairs), we investigated the phenotypic and genetic and environmental architecture of a broad construct of conscientiousness (including conscientiousness per se, effortful control, self-control, and grit). These four different measures were substantially correlated; the coefficients ranged from 0.74 (0.72–0.76) to 0.79 (0.76–0.80). Univariate genetic analyses revealed that individual differences in conscientiousness measures were moderately attributable to additive genetic factors, to an extent ranging from 62 (58–65) to 64% (61–67%); we obtained no evidence that shared environmental influences were observed. Multivariate genetic analyses showed that for the four measures used to assess conscientiousness, genetic correlations were stronger than the corresponding non-shared environmental correlations, and that a latent common factor accounted for over 84% of the genetic variance. Our findings suggest that individual differences in the four measures of conscientiousness are not distinguishable at both the phenotypic and behavioural genetic levels, and that the overlap was substantially attributable to genetic factors.

Adult temperament and childbearing over the life course

Emerging evidence suggests that temperament may predict childbearing. We examined the association between four temperament traits (novelty seeking, harm avoidance, reward dependence and persistence of the Temperament and Character Inventory) and childbearing over the life course in the population‐based Cardiovascular Risk in Young Finns study (n = 1535; 985 women, 550 men). Temperament was assessed when the participants were aged 20–35 and fertility history from adolescence to adulthood was reported by the participants at age 30–45. Discrete‐time survival analysis modelling indicated that high childbearing probability was predicted by low novelty seeking (standardized OR = 0.92; 95% confidence interval 0.88–0.97), low harm avoidance (OR = 0.90; 0.85–0.95), high reward dependence (OR = 1.09; 1.03–1.15) and low persistence (OR = 0.91; 0.87–0.96) with no sex differences or quadratic effects. These associations grew stronger with increase in numbers of children. The findings were substantially the same in a completely prospective analysis. Adjusting for education did not influence the associations. Despite its negative association with overall childbearing, high novelty seeking increased the probability of having children in participants who were not living with a partner (OR = 1.29; 1.12–1.49). These data provide novel evidence for the role of temperament in influencing childbearing, and suggest possible weak natural selection of temperament traits in contemporary humans. Copyright © 2009 John Wiley & Sons, Ltd.

The conceptualisation, measurement and scope of reinforcement sensitivity in the context of a neuroscience of personality

Reinforcement sensitivity theory (RST) is complex, and there are subtle differences between RST and other approach‐avoidance process theories of personality. However, most such theories posit a common biobehavioural mechanism underlying personality which we must therefore strive to understand: differential sensitivity to reinforcing stimuli. Reinforcement sensitivity is widely assessed using questionnaires, but should we treat such measures as (a) a proxy for reinforcement sensitivity itself (i.e. the underlying causes of personality) or (b) trait constructs potentially manifesting out of reinforcement sensitivity (i.e. the ‘surface’ of personality)? Might neuroscience paradigms, such as those I have reviewed in my target paper, provide an advantage over questionnaires in allowing us to move closer to (a), thereby improving both the measurement and our understanding of reinforcement sensitivity? Assuming we can achieve this, how useful is reinforcement sensitivity—and biological perspectives more generally—for explaining personality? These are the major questions raised in the discussion of my target paper, and among the most pertinent issues in this field today. Copyright © 2008 John Wiley & Sons, Ltd.

The genetic and environmental origins of emotional and cognitive empathy: Review and meta-analyses of twin studies

Empathy is considered a cornerstone of human social experience, and as such has been widely investigated from psychological and neuroscientific approaches. To better understand the factors influencing individual differences in empathy, we reviewed and meta-analyzed the behavioral genetic literature of emotional empathy- sharing others' emotions (k=13), and cognitive empathy- understanding others' emotions (k = 15), as manifested in twin studies. Results showed that emotional empathy is more heritable, 48.3 % [41.3 %-50.6 %], than cognitive empathy, 26.9 % [18.1 %-35.8 %]. Moreover, cognitive empathy as examined by performance tests was affected by the environment shared by family members, 11.9 % [2.6 %-21.0 %], suggesting that emotional understanding is influenced, to some degree, by environmental factors that have similar effects on family members beyond their genetic relatedness. The effects of participants' age and the method used to asses empathy on the etiology of empathy were also examined. These findings have implications for understanding how individual differences in empathy are formed. After discussing these implications, we suggest theoretical and methodological future research directions that could potentially elucidate the relations between genes, brain, and empathy.

Temperament and character dimensions of the relatives of schizophrenia patients and controls: The relationship between schizotypal features and personality

Purpose

Previous findings indicated that schizophrenia patients might have a different personality structure from the general population on several dimensions of temperament and character. Some authors proposed that HA might be a marker of underlying genetic vulnerability to schizophrenia. Studies on high-risk subjects and first degree relatives of patients is essential to test the value of a measure as a marker of genetic vulnerability to a disease. Few studies tested the biopsychosocial model of personality on unaffected relatives of schizophrenia.

Subjects and methods

We compared the Temperament and Character (TCI) profiles of 94 first degree relatives of schizophrenia and 75 controls. We also investigated the relationship between schizotypy and TCI dimensions in the study sample.

Results

The harm avoidance scores of the relatives of schizoprenia patients with schizotypal features were significantly higher. Self transcendence scores were also significantly higher among relatives with schizotypal features. In contrast, the relatives of the patients with schizophrenia who did not have schizotypal features had higher SD and C scores than the control group.

Discussion and conclusion

This finding is consistent with the previous findings which suggested harm avoidance as a vulnerability indicator of schizophrenia. Some character features like self transcendence might be also associated with schizotypal features.

Personality-obesity associations are driven by narrow traits: A meta-analysis

Obesity has inconsistent associations with broad personality domains, possibly because the links pertain to only some facets of these domains. Collating published and unpublished studies (N = 14 848), we meta-analysed the associations between body mass index (BMI) and Five-Factor Model personality domains as well as 30 Five-Factor Model personality facets. At the domain level, BMI had a positive association with Neuroticism and a negative association with Conscientiousness domains. At the facet level, we found associations between BMI and 15 facets from all five personality domains, with only some Neuroticism and Conscientiousness facets among them. Certain personality-BMI associations were moderated by sample properties, such as proportions of women or participants with obesity; these moderation effects were replicated in the individual-level analysis. Finally, facet-based personality "risk" scores accounted for 2.3% of variance in BMI in a separate sample of individuals (N = 3569), 409% more than domain-based scores. Taken together, personality-BMI associations are facet specific, and delineating them may help to explain obesity-related behaviours and inform intervention designs. Preprint and data are available at https://psyarxiv.com/z35vn/.

Assessment of Cognition and Personality as Potential Endophenotypes in the Western Australian Family Study of Schizophrenia

Phenotypic heterogeneity is a major barrier to understanding the genetic architecture underlying schizophrenia. Incorporating endophenotypes is one way to reduce heterogeneity and facilitate more powerful genetic analysis. Candidate endophenotypes require systematic assessment against endophenotype criteria, and a ranking of their potential utility for genetic analysis. In this study we assess 20 cognitive and personality measures in a sample of 127 families with at least 2 cases of schizophrenia per family (n = 535) plus a set of 30 control families (n = 121) against 4 endophenotype criteria: (a) be associated with the illness but not be a part of its diagnosis, (b) be heritable, (c) co-segregate with the illness in families, and (d) be found in unaffected relatives at a higher rate than in the general population. The endophenotype ranking score (endophenotype ranking variable [ERV]) was used to rank candidate endophenotypes based on their heritability and genetic correlation with schizophrenia. Finally, we used factor analysis to explore latent factors underlying the cognitive and personality measures. Evidence for personality measures as endophenotypes was at least equivalent to that of the cognitive measures. Factor analysis indicated that personality and cognitive traits contribute to independent latent dimensions. The results suggest for this first time that a number of cognitive and personality measures are independent and informative endophenotypes. Use of these endophenotypes in genetic studies will likely improve power and facilitate novel aetiological insights.

Normative data and effects of age and gender on temperament and character dimensions across the lifespan in an Italian population: A cross-sectional validation study

BACKGROUND

The short version of the Temperament and Character Inventory (TCI-125) has been employed for the study of personality traits in both clinical and normal populations. However, to the best of our knowledge, no studies explored the psychometric properties of this instrument in healthy individuals across the lifespan. We here provide the Italian normative data and present the personality features according to age and gender in a sample of healthy individuals.

METHODS

A cross-sectional study was carried out in a total of 1430 Italian healthy individuals ranging from 13 to 67 years (59.3% females). We evaluated the factorial model of the TCI-125, explored the internal consistency of the scales and carried out univariate analyses of variance for the investigation of age and gender differences in temperament and character dimensions.

RESULTS

Confirmatory factor analysis only partially confirmed the factor structure, with some Reward Dependence, Self-Directedness, and Cooperativeness items showing poor fit. Overall we found acceptable internal consistencies for all the dimensions of the TCI-125 across all age groups, except for Reward Dependence, Persistence, and Novelty Seeking, which showed unsatisfactory internal consistency in younger age groups. Furthermore, we found significant age differences in most temperament and all character dimensions. Finally, in specific age groups we also observed significantly lower scores in males compared to females in Harm Avoidance, Reward Dependence and all character dimensions except for Self-Directedness, on which males scored higher than females.

CONCLUSIONS

Although this study only partially confirmed the factor structure of the TCI-125 and suggested limited homogeneity for some temperament scales, overall our results supported the reliability of the TCI-125, which can therefore be considered a useful tool for exploring personality traits in both clinical and normal samples. Moreover, this study suggested the need of using this instrument with caution in adolescents.

Personality profiles in adults with attention deficit hyperactivity disorder (ADHD)

BACKGROUND

Previous studies suggested that the presence of ADHD in children and young adolescents may affect the development of personality. Whether or not the persistence of ADHD in adult life is associated with distinct personality patterns is still matter for debate. To address this issue, we compared the profiles of the Temperament and Character Inventory (TCI) that assesses personality dimensions in 119 adults ADHD and 403 controls.

METHODS

ANCOVA were used to examine group differences (controls vs. ADHD and ADHD inattentive type vs. ADHD combined + hyperactive/impulsive types) in Temperaments and Characters. Partial correlation coefficients were used to assess correlation between TCI and expression and severity of symptoms of ADHD.

RESULTS

High novelty seeking (NS), harm avoidance (HA) and self-transcendence (ST) scores as well as low self-directedness (SD) and cooperativeness (C) scores were associated with ADHD diagnosis. Low SD was the strongest personality trait associated with adult ADHD. Cases with the ADHD inattentive type showed higher HA and lower SD scores compared to the combined and hyperactive/impulsive types. High HA scores correlated with inattention symptoms whereas high NS and ST scores were related to hyperactive symptoms. Finally low SD and high NS were associated with increased ADHD severity.

CONCLUSIONS

Distinct temperaments were associated with inattentive versus hyperactive/impulsive symptoms supporting the heterogeneous nature of the disorder.

The genetic and environmental structure of the character sub-scales of the temperament and character inventory in adolescence

BACKGROUND

The character higher order scales (self-directedness, cooperativeness, and self-transcendence) in the temperament and character inventory are important general measures of health and well-being [Mens Sana Monograph 11:16-24 (2013)]. Recent research has found suggestive evidence of common environmental influence on the development of these character traits during adolescence. The present article expands earlier research by focusing on the internal consistency and the etiology of traits measured by the lower order sub-scales of the character traits in adolescence.

METHODS

The twin modeling analysis of 423 monozygotic pairs and 408 same sex dizygotic pairs estimated additive genetics (A), common environmental (C), and non-shared environmental (E) influences on twin resemblance. All twins were part of the on-going longitudinal Child and Adolescent Twin Study in Sweden (CATSS).

RESULTS

The twin modeling analysis suggested a common environmental contribution for two out of five self-directedness sub-scales (0.14 and 0.23), for three out of five cooperativeness sub-scales (0.07-0.17), and for all three self-transcendence sub-scales (0.10-0.12).

CONCLUSION

The genetic structure at the level of the character lower order sub-scales in adolescents shows that the proportion of the shared environmental component varies in the trait of self-directedness and in the trait of cooperativeness, while it is relatively stable across the components of self-transcendence. The presence of this unique shared environmental effect in adolescence has implications for understanding the relative importance of interventions and treatment strategies aimed at promoting overall maturation of character, mental health, and well-being during this period of the life span.

The influence of genes on "positive valence systems" constructs: A systematic review

In 2009, the U.S. National Institute of Mental Health (NIMH) proposed an approach toward the deconstruction of psychiatric nosology under the research domain criteria (RDoC) framework. The overarching goal of RDoC is to identify robust, objective measures of behavior, emotion, cognition, and other domains that are more closely related to neurobiology than are diagnoses. A preliminary framework has been constructed, which has connected molecules, genes, brain circuits, behaviors, and other elements to dimensional psychiatric constructs. Although the RDoC framework has salience in emerging studies, foundational literature that pre-dated this framework requires synthesis and translation to the evolving objectives and nomenclature of RDoC. Toward this end, we review the candidate-gene association, linkage, and genome-wide studies that have implicated a variety of loci and genetic polymorphisms in selected Positive Valence Systems (PVS) constructs. Our goal is to review supporting evidence to currently listed genes implicated in this domain and novel candidates. We systematically searched and reviewed literature based on keywords listed under the June, 2011, edition of the PVS matrix on the RDoC website (http://www.nimh.nih.gov/research-priorities/rdoc/positive-valence-systems-workshop-proceedings.shtml), which were supplemented with de novo keywords pertinent to the scope of our review. Several candidate genes linked to the PVS framework were identified from candidate-gene association studies. We also identified novel candidates with loose association to PVS traits from genome-wide studies. There is strong evidence suggesting that PVS constructs, as currently conceptualized under the RDoC initiative, index genetically influenced traits; however, future research, including genetic epidemiological, and psychometric analyses, must be performed.

Maternal personality traits associated with patterns of prenatal smoking and exposure: Implications for etiologic and prevention research

BACKGROUND

Little is known about the characteristics of women who smoke during pregnancy beyond demographic factors. We examined the relationship between novelty seeking, harm avoidance, and self-directedness and (a) abstinence from smoking during pregnancy and (b) average daily cigarette consumption during pregnancy.

METHODS

Participants were 826 birth mothers who made adoption placements in the Early Growth and Development Study and completed the Temperament and Character Inventory - Short Form, and interview-based smoking assessments 3-6 months postpartum. Never smokers (n=199), pregnancy abstainers (n=277), pregnancy light smokers (n=184), and pregnancy heavy smokers (n=166) were compared on personality dimensions and smoking-related processes. Using regression analyses we examined relationships between personality and (a) abstinence versus smoking during pregnancy; and (b) average daily cigarette consumption among lifetime smokers, controlling for nicotine dependence, birth father substance dependence, maternal antisocial behavior, and depressive symptoms during pregnancy.

RESULTS

Smokers with higher self-directedness and lower harm avoidance were more likely to abstain during pregnancy [O.R. 1.380; 95% C.I. (1.065-1.787); B(SE)=.322(.132); p=.015] and [O.R. .713; 95% C.I. (.543-.935); B(SE)=-.339(.138); p=.014], respectively. Novelty seeking differentiated never smokers from lifetime smokers (t=-3.487; p=.001), but was not significant in multivariate models. Lifetime smokers who abstained during pregnancy reported fewer depressive symptoms relative to never smokers.

CONCLUSIONS

Personality dimensions associated with abstinence from smoking and cigarettes per day during pregnancy may be important to consider in etiologic and intervention research.

Validation of the Italian translation of the Revised Temperament and Character Inventory--TCI-140--in adult participants and in participants with medical diseases

INTRODUCTION

This study aimed at assessing the reliability and construct validity of the TCI-140.

SAMPLE

428 Italian participants.

EXCLUSION CRITERIA

psychiatric disorders. 100 subjects - longitudinal retest study.

RESULTS

The results of descriptive statistics of internal consistency reliabilities (Cronbach coefficient) of TCI-R dimensions showed: a strong internal consistence of the scales: HA (α = 0.84); RD (α = 0.70); SD (α = 0.86); C (α = 0.75); ST (α = 0.83); a low level in NS (α = 0.60). In relation to facets, internal consistency reliabilities (Cronbach coefficient) ranged from 0.14 C3 to 0.79 C4 (from 3rd to 4th facet of C scale). Correlations: highest inverse correlation between HA and SD (r = -0.56); moderate inverse correlations for: HA and PS (r = -0.37); C and RD(r = 0.32); C and SD (r = 0.44). P, SD, C and ST showed good inter class correlations (ICC) ≥ 70 maintaining a good stability of the measures over the time. Four factors accounted for 56.3% of the variance for temperament subscale. Subscales of: PS4, PS3 PS2, PS1, NS3 for factor 1; HA2, HA1, HA4, HA3 for factor 2; RD1, RD2 and RD3 for factor 3; NS4, NS1 and NS2 for factor 4. Three factors that were identified accounted for 58.3% of the variance for character subscales of: SD3, SD5, SD1, SD2 for factor 1; C4, C1, C5, SD4, C3 for factor 2; ST2, ST1, ST3, C2 for factor 3.

CONCLUSION

The reliability coefficients were significantly good for some dimensions of TCI-140 and showed a good correlation after time, while some dimensions as NS have low reliability. In the principal components analysis does not saturate all dimensions in its theoretical factor. Moreover TCI-140 is a useful inventory for the evaluation of the principal dimensions of temperament and character.

Some personality traits converge gradually by long-term partnership through the lifecourse--genetic and environmental structure of Cloninger's temperament and character dimensions

Temperament and Character Inventory (TCI) is a comprehensive personality inventory that is widely used in behavioral genetics. The original theory suggested that temperament traits were under genetic influences, whereas character traits were gradually built by an interaction between temperaments and environment until early adulthood. This study attempted to evaluate TCI by examining the genetic and environmental contributions to personality with particular attention to spousal effects. From 687 families, a total of 3459 Korean adult individuals completed the survey. Among them, there were 542 Monozygotic (MZ) twin pairs and 122 Dizygotic twin pairs. Intraclass correlation coefficients (ICCs) and heritability were calculated to examine the genetic and shared environmental contributions to personality. Moderate genetic contributions (0.17-0.43) were found for all TCI traits along with the evidence of shared environment (0.11-0.31) for harm avoidance (HA) and all characters. The ICCs of TCI in MZ pairs ranged 0.36-0.46. Spouses' had little resemblance for temperament, whereas for character dimensions, spouses (0.27-0.38) were more similar than first degree relatives (0.10-0.29). Resemblance between spouses increased with duration of marriage for most characters and HA. When the growing similarities between spouses were compared with their MZ cotwins' for subgroup of 81 trios, self-directedness (SD) of character showed even more similarities toward their spouses than cotwins as partnership duration increased (r = 0.32). Our findings with regard to change in SD into late adulthood support the psychobiological theory of temperament and character, which suggests that both personality domains have distinct developmental trajectories despite equally large genetic influences.

Genetic and environmental influences underlying the relationship between autistic traits and temperament and character dimensions in adulthood

BACKGROUND

In recent years, several twin studies adopted a dimensional approach to Autism Spectrum Disorders (ASD) and estimated the contribution of genetic and environmental influences to variation in autistic traits. However, no study was performed on adults over 18 years of age and all but two studies were based on parent or teacher ratings. Also, the genetic and environmental contributions to the interplay between autistic traits and adult personality dimensions have not been investigated.

METHODS

A sample of 266 complete twin pairs (30% males, mean age 40 ± 12 years) drawn from the population-based Italian Twin Register was administered the Autism-Spectrum Quotient, Temperament and Character Inventory (TCI-125), and General Health Questionnaire (GHQ-12). Genetic structural equation modelling was performed with the Mx program. Estimates were adjusted for gender, age, and GHQ-12 score.

RESULTS

Genetic factors accounted for 44% and 20%-49% of individual differences in autistic traits and TCI dimensions, respectively. Unshared environmental factors explained the remaining proportion of variance. Consistently with the notion of a personality profile in ASD characterised by obsessive temperament, autistic traits showed significant phenotypic correlations with several TCI dimensions (positive: HA; negative: NS, RD, SD, C). Genetic and unshared environmental correlations between AQ and these TCI dimensions were significant. The degree of genetic overlap was generally greater than the degree of environmental overlap.

CONCLUSIONS

Despite some limitations, this study suggests that genetic factors contribute substantially to individual differences in autistic traits in adults, with unshared environmental influences also playing an important role. It also suggests that autistic traits and the majority of temperament and character dimensions share common genetic and environmental aetiological factors.

The prosocial personality and its facets: genetic and environmental architecture of mother-reported behavior of 7-year-old twins

Children vary markedly in their tendency to behave prosocially, and recent research has implicated both genetic and environmental factors in this variability. Yet, little is known about the extent to which different aspects of prosociality constitute a single dimension (the prosocial personality), and to the extent they are intercorrelated, whether these aspects share their genetic and environmental origins. As part of the Longitudinal Israeli Study of Twins (LIST), mothers of 183 monozygotic (MZ) and dizygotic (DZ) 7-year-old twin pairs (51.6% male) reported regarding their children’s prosociality using questionnaires. Five prosociality facets (sharing, social concern, kindness, helping, and empathic concern) were identified. All five facets intercorrelated positively (r > 0.39) suggesting a single-factor structure to the data, consistent with the theoretical idea of a single prosociality trait. Higher MZ than DZ twin correlations indicated genetic contributions to each prosociality facet. A common-factor-common-pathway multivariate model estimated high (69%) heritability for the common prosociality factor, with the non-shared environment and error accounting for the remaining variance. For each facet, unique genetic and environmental contributions were identified as well. The results point to the presence of a broad prosociality phenotype, largely affected by genetics; whereas additional genetic and environmental factors contribute to different aspects of prosociality, such as helping and sharing.

Ventral striatal dopamine synthesis capacity is associated with individual differences in behavioral disinhibition

Pathological gambling, alongside addictive and antisocial disorders, forms part of a broad psychopathological spectrum of externalizing disorders, which share an underlying genetic vulnerability. The shared externalizing propensity is a highly heritable, continuously varying trait. Disinhibitory personality traits such as impulsivity and novelty seeking (NS) function as indicators of this broad shared externalizing tendency, which may reflect, at the neurobiological level, variation in the reactivity of dopaminergic (DAergic) brain reward systems centered on the ventral striatum (VS). Here, we examined whether individual differences in ventral striatal dopamine (DA) synthesis capacity were associated with individual variation in disinhibitory personality traits. Twelve healthy male volunteers underwent 6-[¹⁸F]Fluoro-L-DOPA (FDOPA) positron emission tomography (PET) scanning to measure striatal DA synthesis capacity, and completed a measure of disinhibited personality (NS). We found that levels of ventral, but not dorsal, striatal DA synthesis capacity were significantly correlated with inter-individual variation in disinhibitory personality traits, particularly a propensity for financial extravagance and irresponsibility. Our results are consistent with preclinical models of behavioral disinhibition and addiction proneness, and provide novel insights into the neurobiology of personality based vulnerability to pathological gambling and other externalizing disorders.

Deletion of SHATI/NAT8L increases dopamine D1 receptor on the cell surface in the nucleus accumbens, accelerating methamphetamine dependence

In a previous report, we identified a novel molecule, SHATI/NAT8L, having an inhibitory effect on methamphetamine (METH)-induced hyperlocomotion, sensitization, and conditioned place preference (CPP). SHATI/NAT8L attenuates the METH-induced increase in dopamine overflow in the nucleus accumbens (NAc) by promoting plasmalemmal and vesicular dopamine uptake. However, the biological functions of the protein remain unclear. In this study, we explored NAT8L-binding proteins using pull-down assays and identified a number of components of the adaptor protein (AP)-2 complex, which is a multimeric protein localized to the plasma membrane that functions to internalize cargo during clathrin-mediated endocytosis. To investigate whether NAT8L regulates the receptor localization to the cell surface, cell-surface dopamine D1 receptor in the NAc of Nat8l knockout (KO) mice was quantified. We found that dopamine D1 receptor on the cell surface was increased in the NAc of Nat8l KO mice compared with the wild type (WT) animals. Consistent with this finding, Nat8l KO mice showed higher basal locomotor activity and heightened sensitivity to D1 agonist compared with WT mice. In addition, METH-induced sensitization and CPP were enhanced in Nat8l KO mice. These results suggest that NAT8L might regulate the localization of cell-surface dopamine D1 receptor, thereby controlling basal behaviour and sensitivity to METH. Furthermore, we observed a single nucleotide polymorphism (SNP) in the human NAT8L gene related to reward dependence, a personality trait, and grey matter volume in the caudate nucleus in healthy subjects, suggesting that NAT8L might also affect human personality.

Genetic and environmental bases of the interplay between magical ideation and personality

Sub-threshold psychotic symptoms are quite commonly present in general population. Among these, Magical Ideation (MI) has been proved to be a valid predictor of psychosis. However, the genetic and environmental influences on the interplay between MI and personality have not fully been explored. A total of 534 adult twins from the population-based Italian Twin Register were assessed for MI using the MI Scale (MIS) and for personality with the temperament and character inventory (TCI). A Multivariate Cholesky model was applied with Mx statistical program. The best-fitting model showed that additive genetic and unshared environmental factors explain approximately the same proportion of variance in MI, whereas a less strong genetic influence on personality traits emerged. Relevant correlations between MI and specific personality traits (novelty seeking, cooperativeness, self-directedness, self-transcendence) were found, suggesting shared influences for MI and these traits. Both genetic and environmental factors explained these correlations, with genetic factors playing a predominant role. Moderate-to-substantial genetic effects on MI and personality were found. Shared genetic and environmental effects underlie the phenotypic correlation between MI (psychosis-proneness) and personality traits, i.e. self-directedness (negative association) and self-transcendence (positive association), potentially representing predictive markers of psychosis liability related to schizotypy and personality.

ADHD, autism spectrum disorder, temperament, and character: phenotypical associations and etiology in a Swedish childhood twin study

OBJECTIVE

To explore the links between neurodevelopmental disorders - attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) - and personality in a population-based, genetically sensitive study of children.

METHOD

A population-based sample of 1886 twins aged 9 and 12, enriched for childhood mental health problems, was recruited from the Child and Adolescent Twin Study in Sweden (CATSS). Parents were interviewed over the telephone using the Autism-Tics, AD/HD and other Comorbidities (A-TAC) inventory, and in a second step they rated their children according to the Junior Temperament and Character Inventory (JTCI).

RESULTS

ADHD was strongly correlated with novelty seeking, while ASD was correlated positively with harm avoidance and negatively with reward dependence. The strongest associations between personality traits and neurodevelopmental disorders were negative correlations between the character dimensions of self-directedness and cooperativeness and ADHD and ASD alike. Cross-twin cross-trait correlations between ADHD, ASD, and personality dimensions in monozygotic twins were more than double those in dizygotic twins, indicating a strong genetic effect behind the phenotypic covariation between neurodevelopmental disorders and personality.

CONCLUSIONS

Neurodevelopmental disorders are linked specifically to particular temperament profiles and generally to hampered development of the self-governing strategies referred to as "character." Poor self-agency and cooperation may be core functional outcomes in the separation of children with handicapping conditions from those with traits only reminiscent of neurodevelopmental disorders. The associations between neurodevelopmental disorders and personality are at least partly due to genetic effects influencing both conditions. As a consequence, personality must be broadly considered in neuropsychiatry, just as neuropsychiatric disorders and their genetic, neurodevelopmental, and cognitive susceptibilities have to be in personality research and clinical treatment.

Temperament and character in the Child and Adolescent Twin Study in Sweden (CATSS): comparison to the general population, and genetic structure analysis

Background

The Child and Adolescent Twin Study in Sweden (CATSS) is an on-going, large population-based longitudinal twin study. We aimed (1) to investigate the reliability of two different versions (125-items and 238-items) of Cloninger's Temperament and Character Inventory (TCI) used in the CATSS and the validity of extracting the short version from the long version, (2) to compare these personality dimensions between twins and adolescents from the general population, and (3) to investigate the genetic structure of Cloninger's model.

Method

Reliability and correlation analyses were conducted for both TCI versions, 2,714 CATSS-twins were compared to 631 adolescents from the general population, and the genetic structure was investigated through univariate genetic analyses, using a model-fitting approach with structural equation-modeling techniques based on same-sex twin pairs from the CATSS (423 monozygotic and 408 dizygotic pairs).

Results

The TCI scores from the short and long versions showed comparable reliability coefficients and were strongly correlated. Twins scored about half a standard deviation higher in the character scales. Three of the four temperament dimensions (Novelty Seeking, Harm Avoidance, and Persistence) had strong genetic and non-shared environmental effects, while Reward Dependence and the three character dimensions had moderate genetic effects, and both shared and non-shared environmental effects.

Conclusions

Twins showed higher scores in character dimensions compared to adolescents from the general population. At least among adolescents there is a shared environmental influence for all of the character dimensions, but only for one of the temperament dimensions (i.e., Reward Dependence). This specific finding regarding the existence of shared environmental factors behind the character dimensions in adolescence, together with earlier findings showing a small shared environmental effects on character among young adults and no shared environmental effects on character among adults, suggest that there is a shift in type of environmental influence from adolescence to adulthood regarding character.

Genetic associations between the ADHD symptom dimensions and Cloninger's temperament dimensions in adult twins

Previous studies have identified phenotypic associations between Cloninger's temperament dimensions and the symptoms of attention deficit hyperactivity disorder (ADHD) in adults. However the underlying aetiology of these associations remains unclear. We investigate the extent to which genetic and environmental influences contribute to the relationship between temperament and ADHD, examining the ADHD symptoms of inattention (IA) and hyperactivity/impulsivity (HI) separately. Participants were 886 adult twin pairs aged 19-20 years. ADHD symptoms of IA and HI were measured using a DSM-IV based rating scale. Temperament was measured using Cloninger's Temperament and Character Inventory (TCI), across four dimensions: novelty seeking (NS), harm avoidance (HA), reward dependence (RD) and persistence (PS). The twin method was used to decompose phenotypic variance/covariance among these variables into genetic and environmental components. We found that NS was genetically associated with both ADHD symptom dimensions (IA and HI), but that HA was genetically associated with IA only. There was also some evidence of genetic association between PS, IA and HI. These findings suggest that unique profiles of temperament are genetically related to the two ADHD symptom dimensions in adults. Further work is now needed to elucidate the mechanisms that underlie both the combined and separate symptom factor domains of ADHD.

Temperament, character and serotonin activity in the human brain: a positron emission tomography study based on a general population cohort

BACKGROUND

The psychobiological model of personality by Cloninger and colleagues originally hypothesized that interindividual variability in the temperament dimension 'harm avoidance' (HA) is explained by differences in the activity of the brain serotonin system. We assessed brain serotonin transporter (5-HTT) density in vivo with positron emission tomography (PET) in healthy individuals with high or low HA scores using an 'oversampling' study design. Method Subjects consistently in either upper or lower quartiles for the HA trait were selected from a population-based cohort in Finland (n = 2075) with pre-existing Temperament and Character Inventory (TCI) scores. A total of 22 subjects free of psychiatric and somatic disorders were included in the matched high- and low-HA groups. The main outcome measure was regional 5-HTT binding potential (BPND) in high- and low-HA groups estimated with PET and [11C]N,N-dimethyl-2-(2-amino-4-methylphenylthio)benzylamine ([11C]MADAM). In secondary analyses, 5-HTT BPND was correlated with other TCI dimensions.

RESULTS

5-HTT BPND did not differ between high- and low-HA groups in the midbrain or any other brain region. This result remained the same even after adjusting for other relevant TCI dimensions. Higher 5-HTT BPND in the raphe nucleus predicted higher scores in 'self-directedness'.

CONCLUSIONS

This study does not support an association between the temperament dimension HA and serotonin transporter density in healthy subjects. However, we found a link between high serotonin transporter density and high 'self-directedness' (ability to adapt and control one's behaviour to fit situations in accord with chosen goals and values). We suggest that biological factors are more important in explaining variability in character than previously thought.

Two Cohort and Three Independent Anonymous Twin Projects at the Keio Twin Research Center (KoTReC)

The Keio Twin Research Center has conducted two longitudinal twin cohort projects and has collected three independent and anonymous twin data sets for studies of phenotypes related to psychological, socio-economic, and mental health factors. The Keio Twin Study has examined adolescent and adult cohorts, with a total of over 2,400 pairs of twins and their parents. DNA samples are available for approximately 600 of these twin pairs. The Tokyo Twin Cohort Project has followed a total of 1,600 twin pairs from infancy to early childhood. The large-scale cross-sectional twin study (CROSS) has collected data from over 4,000 twin pairs, from 3 to 26 years of age, and from two high school twin cohorts containing a total of 1,000 pairs of twins. These data sets of anonymous twin studies have mainly targeted academic performance, attitude, and social environment. The present article introduces the research designs and major findings of our center, such as genetic structures of cognitive abilities, personality traits, and academic performances, developmental effects of genes and environment on attitude, socio-cognitive ability and parenting, genes x environment interaction on attitude and conduct problem, and statistical methodological challenges and so on. We discuss the challenges in conducting twin research in Japan.

The heritability of Cluster B personality disorders assessed both by personal interview and questionnaire

Whereas the heritability of common personality traits has been firmly established, the results of the few published studies on personality disorders (PDs) are highly divergent, with some studies finding high heredity and others very low. A problem with assessing personality disorders by means of interview is errors connected with interviewer bias. A way to overcome the problem is to use self-report questionnaires in addition to interviews. This study used both interview and questionnaire for assessing DSM-IV Cluster B personality disorders: antisocial personality disorder (APD), borderline (BPD), narcissistic (NPD), and histrionic (HPD). We assessed close to 2,800 twins from the Norwegian Institute of Public Health Twin Panel using a self-report questionnaire and, a few years later, the Structured Interview for DSM-IV Personality (SIDP-IV). Items from the self-report questionnaire that best predicted the PDs captured by the interview were then selected. Measurement models combining questionnaire and interview information were applied and were fitted using Mx. Whereas the heritability of Cluster B PDs assessed by interview was around .30, and around .40-.50 when assessed by self-report questionnaire, the heritability of the convergent latent factor, including information from both interview and self-report questionnaire was .69 for APD, .67 for BPD, .71 for NPD, and .63 for HPD. As is usually found for personality, the effect of shared-in families (familial) environment was zero. In conclusion, when both interview and self-report questionnaire are taken into account, the heritability of Cluster B PD appears to be in the upper range of previous findings for mental disorders.

Culture Moderates the Genetic and Environmental Etiologies of Parenting

A cultural behavior genetic approach was introduced as a prospective means to describe psychological differences between cultures. We compared genetic and environmental influences on remembered parenting for samples of twins from Japan and Sweden. Data were collected from 720 pairs of young adult Japanese twins and 824 pairs of adult Swedish twins using the Parental Bonding Instrument. In both samples, a very similar phenotypic factor structure was developed for maternal and paternal parenting. However, the genetic and environmental contributions were different. Parenting in Japan showed more genetic influences, whereas parenting in Sweden showed more shared environmental influences. Moreover, covariation among the six dimensions of parenting (i.e., maternal and paternal Warmth, Protectiveness, and Authoritarianism) was due to genetic correlations in Japan and to shared environmental correlations in Sweden. These results are consistent with the cultural psychology argument that parenting practices are child centered in Japan but parent centered in the West.

Investigating the development of temperament and character in school-aged children using a self-report measure

BACKGROUND

Developmental studies of temperament and character dimensions are crucial for a better understanding of how genetic and environmental factors interact in shaping individual personality. However, although several studies have been conducted in adults, a few studies have addressed the evaluation of temperament and character in children. Here, we tested the suitability of self-report evaluation and the developmental trend of temperament and character dimensions among school-aged children using an Italian version of the junior Temperament and Character Inventory (jTCI).

METHODS

The jTCI was completed by 572 Italian children (292 girls and 280 boys) aged 8 to 12 years. We evaluated the internal consistency of the 7 jTCI scales at each age, the intercorrelations between the scales, and the factorial model of the questionnaires. Furthermore, we tested the differences between the development of the temperament and character dimensions in girls and boys.

RESULTS

Although the data from 8-year children showed unacceptably low internal consistency, better reliability was observed for older children. Intercorrelations and factor analysis partially confirmed the hypothesized structure of the jTCI items, with problems observed for some items of the Novelty Seeking, Harm Avoidance, Reward Dependence (RD), and Self-Directedness scales. Furthermore, in keeping with previous studies, girls presented lower scores in Novelty Seeking and higher RD, Self-Directedness, and Cooperativeness scales than did boys, with the between-sex difference in RD becoming larger at older ages.

CONCLUSIONS

Although the use of the self-administered jTCI in clinical settings should be cautious, it may serve as a useful complementary instrument to describe the development of personality in childhood.

A General Factor of Personality From Multitrait–Multimethod Data and Cross–National Twins

In three studies, a General Factor of Personality (GFP) was found to occupy the apex of the hierarchical structure. In Study 1, a GFP emerged independent of method variance and accounted for 54% of the reliable variance in a multitrait–multimethod assessment of 391 Italian high school students that used self-, teacher-, and parent-ratings on the Big Five Questionnaire — Children. In Study 2, a GFP was found in the seven dimensions of Cloninger's Temperament and Character Inventory as well as the Big Five of the NEO PI-R, with the GFPtci correlatingr= .72 with the GFPneo. These results indicate that the GFP is practically the same in both test batteries, and its existence does not depend on being extracted using the Big Five model. The GFP accounted for 22% of the total variance in these trait measures, which were assessed in 651 pairs of 14- to 30-year-old Japanese twins. In Study 3, a GFP accounted for 32% of the total variance in nine scales derived from the NEO PI-R, the Humor Styles Questionnaire, and the Trait Emotional Intelligence Questionnaire assessed in 386 pairs of 18- to 74-year-old Canadian and U.S. twins. The GFP was found to be 50% heritable with high scores indicating openness, conscientiousness, sociability, agreeableness, emotional stability, good humor and emotional intelligence. The possible evolutionary origins of the GFP are discussed.

The University of British Columbia Twin Project: Personality is Something and Personality Does Something

The University of British Columbia (UBC) Twin Project is a registry of approximately 1500 pairs of reared-together twins recruited from Vancouver, British Columbia and surrounding municipalities. The focus of the project is to examine personality and its disorders from a behavioral genetic perspective. The primary measures include self-report measures of variables from the major models of personality and personality disorders. Subsamples of the study have also been surveyed on a wide range of psychiatric conditions and symptoms, including, for example, substance use, mood, anxiety, coping, posttraumatic stress disorder, schizotypy, and several measures of the environment and experience. Also surveyed are general health and basic psychological processes including cognitive ability. This broad assessment has enabled us to examine not only the structure of personality, but also its potential role in psychopathology and other psychological processes. A feature of the project is that the measures selected reflect current thinking in the field as opposed to traditional psychiatric diagnostic criteria. The UBC Twin Project has been used in a number of collaborative projects on personality and psychopathology with other worldwide twin registries. At the present time, no DNA has been collected; however the facility to collect these data is available. Collaborative projects on this and future questionnaire studies are welcome.

Genetic and Environmental Etiology of Effortful Control

We examined whether effortful control (EC), a temperament proposed by Rothbart and Bates (1998), has genetically coherent structure. A self- report measure of EC was administered to 450 Japanese twins (151 males and 299 females, ages 17 to 32 years) including 152 monozygotic and 73 dizygotic pairs. Univariate genetic analysis revealed that AE model fit best for the total EC as well as its subscales. The heritability estimate for total EC was 49%, and the estimates for subscales ranged between 32% and 45%. Multivariate genetic analysis revealed that the subscales of EC were genetically correlated to a high degree and environmentally correlated to a moderate degree. These results suggest that EC has substantial genetic basis and genetically coherent structure, supporting the validity of the construct. The implications to molecular genetic study and study of psychopathology were discussed.

Evidence for Nonadditive Genetic Effects on Eysenck Personality Scales in South Korean Twins

While evidence supporting for nonadditive genetic influences on personality traits in Caucasian populations has been growing in recent years, twin studies that explored the existence of genetic nonadditivity in personality variation in Asian populations are still lacking. Seven hundred and sixty-five pairs of adolescent and young adult twins registered with the South Korean Twin Registry completed the 7 scales of the Eysenck Personality Scales through a mail survey. Maximum likelihood twin correlations were computed and model-fitting analyses were conducted. Monozygotic twin correlations were consistently higher than twice the dizygotic twin correlations for all 7 scales, suggesting pervasive influences of nonadditive genetic effects on personality traits in the South Korean population. Model-fitting analyses indicated that genetic nonadditivity is particularly important for the variation of Impulsivity, Venturesomeness, Empathy, Lie, and Psychoticism. According to the best fitting models, nonadditive genetic effects ranged from 34 to 49% for these scales. For Neuroticism and Extraversion, models that included an additive genetic component fit better than those including a nonadditive genetic variance component.

Registry of Adolescent and Young Adult Twins in the Tokyo Area

Since established in 1998, the Keio Twin Project (KTP) has been dedicated to investigating genetic and environmental sources contributing to human psychological traits in adolescence and young adulthood. A population-based twin registry was constructed by the KTP through the use of official residential records in the Tokyo area, and to date requests to participate in our research have generated 1040 pairs of twins and triplets of age 14 to 30, forming one of the largest twin registries in Asia. Our comprehensive datasets, obtained through questionnaires, performance tests, and physical measurements, cover a wide range of human traits: personality, psychiatry, mental health, sociality, cognition, and physical index. Demographic variables and environment of upbringing are also sought by twins and by some parents. This extensive information allows us to clarify the genetic and environmental overlap across multiple traits as well as specificities unique to single traits. Adding an evolutionary psychology perspective to the behavior genetics framework is currently being attempted in order to develop a grand theory of human genetics.

Evidence for Shared Genetic Dominance Between the General Factor of Personality, Mental and Physical Health, and Life History Traits

We reanalyze previously published data on 309 MZ and 333 DZ twin pairs aged 25 to 74 years from the MIDUS survey, a nationally representative archived sample, to examine how much of the genetic covariance between a general factor of personality (GFP), a lower-order life history factor, and a general physical and mental health factor, is of the nonadditive variety. We found nonadditive genetic effects (D) could not be ruled out as a contributor to the shared variance of these three latent factors to a Super-K Life History factor. We suggest these genetic correlations support the view that a slow (K-selected) life history strategy, good health, and the GFP coevolved and are mutually coadapted through directional selection.

Personality traits in patients with Parkinson's disease: assessment and clinical implications

This study reviews empirical evidence on the association between personality traits and Parkinson's disease (PD), with a twofold aim. First, to better identify non-motor symptoms, such as affective symptoms and personality changes, that could help to define the pre-motor phase of PD; second, to better understand the neurobiological bases of personality traits, a goal that is not fully accomplished by a purely anatomical approach. A literature review was performed on studies of personality traits in PD patients, in electronic databases ISI Web of Knowledge, Medline and PsychInfo, conducted in July 2011. We found evidence that the existence of a characteristic premorbid personality profile of PD patients is not actually sustained by robust empirical evidence, mainly due to the methodological bias of the retrospective assessment of personality; PD patients present a personality profile of low novelty seeking and high harm avoidance. We concluded that the definition of a pre-motor phase of PD, based on non-motor symptoms, should search for the presence of concomitant affective disorders and for a positive psychiatric history for affective disorders rather than for a typical personality profile or personality changes. The low novelty seeking profile is probably related to the dopaminergic deficit, while the high harm avoidance profile is probably associated with the presence of affective disorders. Clinical implications of these findings, in regard to personality assessment and pharmacological treatments in PD, are also discussed.

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.

Depersonalization and personality in panic disorder

BACKGROUND

Prevalence and clinical correlates of depersonalization symptoms have been associated with panic disorder. Personality traits might increase the likelihood of experiencing depersonalization symptoms or depersonalization disorder in panic patients.

AIMS

The objectives of this study are to establish the prevalence of depersonalization symptoms during the panic attack and in depersonalization disorder and to examine the personality factors associated with the presence of depersonalization in patients with panic disorder.

METHODS

The sample comprised 104 consecutive adult outpatients with panic disorder, diagnosed according to the Semistructured Clinical Interview for DSM-IV (Axis I/II disorders). Participants were assessed with the Cambridge Depersonalization Scales, the Temperament and Character Inventory, and the Panic and Agoraphobia Scale.

RESULTS

Forty-eight percent of the sample had depersonalization symptoms during the panic attack, whereas 20% of patients had a depersonalization disorder. Women presented more depersonalization disorders than did men (P = .036). Patients with panic disorder with depersonalization disorder had a more severe panic disorder (P = .002). Logistic regression analysis showed that self-transcendence trait (odds ratio, 1.089; 95% confidence interval, 1.021-1.162; P = .010) and severity of panic (odds ratio, 1.056; 95% confidence interval, 1.005-1.110; P = .032) were independently associated with depersonalization disorder.

CONCLUSIONS

A high prevalence of depersonalization symptoms and depersonalization disorder was confirmed in patients with panic disorder, supporting a dosage effect model for understanding depersonalization pathology. Self-transcendence trait and severity of panic disorder were reported as risk factors for depersonalization disorder.

The interaction between serotonin receptor 2A and catechol-O-methyltransferase gene polymorphisms is associated with the novelty-seeking subscale impulsiveness

OBJECTIVE

Novelty seeking is a trait that has been consistently associated with problem behaviours. There is evidence for heritability of novelty seeking, but the molecular genetic basis of the trait is still widely unclear.

METHODS

The interaction between polymorphisms of catechol-O-methyltransferase (COMT) and serotonin receptor 2A genes was examined in relation to novelty seeking and its different subscales in healthy Finnish adults. A subsample of 1214 participants derived from a population-based sample was genotyped for the COMT Val158Met (rs4680) and HTR2A T102C (rs6313) genes. Novelty seeking was measured twice, with a 4-year interval, using Cloninger's Temperament and Character Inventory.

RESULTS

The interaction between COMT Val158Met and HTR2A T102C polymorphisms was found to be associated with subscale impulsiveness. T/T carriers of HTR2A T102C polymorphism, that also had Met/Met genotype of COMT Val158Met single nucleotide polymorphism, scored significantly higher on impulsiveness than Val allele carriers (P=0.005).

CONCLUSION

Our results suggest that the interaction between dopaminergic and serotonergic genes might underlie impulsiveness. Together with earlier research our results also stress the importance of considering novelty seeking as a heterogeneous trait with its subscales having different genetic backgrounds.

Relationship between Personality and Insomnia in Panic Disorder Patients

OBJECTIVE

Panic disorder (PD) is frequently comorbid with insomnia, which could exacerbate panic symptoms and contribute to PD relapse. Research has suggested that characteristics are implicated in both PD and insomnia. However, there are no reports examining whether temperament and character affect insomnia in PD. Thus, we examined the relationship between insomnia and personality characteristics in PD patients.

METHODS

Participants were 101 patients, recruited from 6 university hospitals in Korea, who met the DSM-IV-TR criteria for PD. We assessed sleep outcomes using the sleep items of 17-item Hamilton Depression Rating Scale (HAMD-17)(item 4=onset latency, item 5=middle awakening, and item 6=early awakening) and used the Cloninger's Temperament and Character Inventory-Revised-Short to assess personality characteristics. To examine the relationship between personality and insomnia, we used analysis of variance with age, sex, and severity of depression (total HAMD scores minus sum of the three sleep items) as the covariates.

RESULTS

There were no statistical differences (p>0.1) in demographic and clinical data between patients with and without insomnia. Initial insomnia (delayed sleep onset) correlated to a high score on the temperamental dimension of novelty seeking 3 (NS3)(F(1,96)=6.93, p=0.03). There were no statistical differences (p>0.1) in NS3 between patients with and without middle or terminal insomnia.

CONCLUSION

The present study suggests that higher NS3 is related to the development of initial insomnia in PD and that temperament and character should be considered when assessing sleep problems in PD patients.