Genetic and environmental covariations among obsessive-compulsive symptoms, neuroticism, and extraversion in South Korean adolescent and young adult twins

Relationships between obsessive-compulsive disorder and the big five personality traits: A meta-analysis

Although several studies have examined the relationships between obsessive-compulsive disorder (OCD) and the Big Five personality traits (i.e., neuroticism, extraversion, openness, agreeableness, and conscientiousness), the results have been inconsistent. Therefore, this meta-analysis comprehensively examined the relationships between OCD and these traits. In total, 23 studies (29 independent datasets) with 30,138 participants were analyzed. The pooled effect size was 0.34 (95% confidence interval [CI]: 0.28, 0.40) for neuroticism, -0.14 (95% CI: -0.18, -0.10) for extraversion, -0.04 (95% CI: -0.09, 0.02) for openness, -0.10 (95% CI: -0.16, -0.04) for agreeableness, and -0.03 (95% CI: -0.11, 0.05) for conscientiousness, indicating that OCD was associated with higher scores for neuroticism and lower scores for extraversion and agreeableness. Meta-regression and subgroup analyses indicated that heterogeneity was mainly due to differences in sample types and OCD measurement instruments. Sensitivity analysis showed that the results of the meta-analysis were robust. Overall, neuroticism was a maladaptive trait, whereas extraversion and agreeableness were adaptive traits for OCD. Although the results could be sample- and instrument-specific, our findings may inform preventions and interventions for OCD symptoms.

Common genetic and environmental bases of the mental disorders and personality traits: Special focus on the hierarchical model of psychopathology and NEO-PI-R facets

OBJECTIVE

This study examined whether phenotypic correlations between psychopathological dimensions and personality traits of different hierarchical levels originate from common genetic and environmental sources of variance.

METHOD

Participants were 386 monozygotic and 204 dizygotic twins. The Psychiatric Diagnostic Screening Questionnaire (PDSQ) was applied along with the Revised NEO Personality Inventory (NEO-PI-R). The results of the CFA confirmed the hypothesis of the internalizing and externalizing dimensions underlying PDSQ scales.

RESULTS

The results indicated a significantly greater role of genetic compared to environmental factors in the relationship between internalizing psychopathology and personality traits. Facets of neuroticism showed positive genetic links with internalizing disorders, while negative genetic links were shown for all facets of extraversion except excitement-seeking, competence, self-discipline, achievement striving, actions, and trust. Lower-order personality traits were shown to be associated with internalizing disorders more intensively than the broader domains to which they belong, both at the phenotypic and genetic levels.

CONCLUSIONS

High neuroticism, together with several facets from the domain of extraversion and conscientiousness seems to represent an increased genetic susceptibility to the disorders from the internalizing spectrum. Results also suggest that specific environmental factors which are not shared with personality traits contribute to the internalizing symptoms.

The genetic epidemiology of obsessive-compulsive disorder: a systematic review and meta-analysis

The first systematic review and meta-analysis of obsessive-compulsive disorder (OCD) genetic epidemiology was published approximately 20 years ago. Considering the relevance of all the studies published since 2001, the current study aimed to update the state-of-art knowledge on the field. All published data concerning the genetic epidemiology of OCD from the CENTRAL, MEDLINE, EMBASE, BVS, and OpenGrey databases were searched by two independent researchers until September 30, 2021. To be included, the articles had to fulfill the following criteria: OCD diagnosis provided by standardized and validated instruments; or medical records; inclusion of a control group for comparison and case-control, cohort or twin study designs. The analysis units were the first-degree relatives (FDRs) of OCD or control probands and the co-twins in twin pairs. The outcomes of interest were the familial recurrence rates of OCD and the correlations of OCS in monozygotic compared with dizygotic twins. Nineteen family, twenty-nine twin, and six population-based studies were included. The main findings were that OCD is a prevalent and highly familial disorder, especially among the relatives of children and adolescent probands, that OCD has a phenotypic heritability of around 50%; and that the higher OCS correlations between MZ twins were mainly due to additive genetic or to non-shared environmental components.

Anxious temperament and cyberchondria as mediated by fear of COVID-19 infection: A cross-sectional study

This study's main goal was to evaluate the association between anxious temperament and the fear of COVID-19-related self-infection and infection in loved ones (family members, friends, relatives) and cyberchondria. The sample consisted of 499 men and women aged between 18 and 72 who were gathered from the general population via an online recruitment platform. A numerical rating scale comprising 11 degrees of fear was used to assess participants' COVID-19-related fear, and affective temperaments were evaluated using Akiskal's Temperament Evaluation of the Memphis, Pisa, Paris and San Diego Autoquestionnaire (TEMPS-A) scales. Cyberchondria was assessed using McElroy and Shevlin's Cyberchondria Severity Scale (CSS). Small to medium positive correlations were found between depressive, cyclothymic, irritable and anxious temperaments and cyberchondria and between depressive and anxious temperaments and COVID-19 fears. However, no correlation was observed between the hyperthymic temperament and cyberchondria. Cyberchondria positively correlated with both COVID-19 fears scales, though the correlation coefficients were medium. Based on the results of linear regression analysis, only anxious temperament and COVID-19 fear of self-infection were significant predictors of cyberchondria. The analysis also revealed a significant indirect effect of anxious temperament on cyberchondria through fear of COVID-19 self-infection as a mediator between anxious temperament and cyberchondria.

The South Korean Twin Registry

The South Korean Twin Registry (SKTR) is an ongoing nationwide volunteer registry of South Korean twins and their families. Since its inception, from preschooler to young adult, twins have been registered with the SKTR and have demonstrated that relative influences of genetic and environmental factors explaining individual differences in various psychological, mental health and physical traits in South Koreans are similar to those found in many Western twin studies. Currently, studies at the SKTR focus on identification of the process of gene-by-environment interactions as well as developmental differences in genetic and environmental influences on psychological and mental health traits in South Koreans. This report provides a brief overview, recruitment strategies, current samples, zygosity assessment, measures and future directions of the SKTR.

A multilevel longitudinal study of obsessive compulsive symptoms in adolescence: male gender and emotional stability as protective factors

The severity of obsessive compulsive symptoms (OCS) is suggested to be normally distributed in the general population, and they appear to have an impact on a range of aspects of adolescent development. Importantly, there are individual differences regarding susceptibility to OCS. In the present repeated measures study, OCS were studied in relation to gender and emotional stability (as a personality trait) using a normative sample of 515 adolescents at ages 16 and 18 years. OCS were assessed with the relevant subscale of the SCL-90-R and emotional stability with the Five Factor Questionnaire. A three-level hierarchical linear model was calculated to longitudinally assess the over time variations of OCS and their over time links to gender and emotional stability, while controlling for random effects due to the nesting of the data. Experiencing OCS increased with age (between 16 and 18 years). Additionally, male gender and higher emotional stability were associated with lower OCS at 16 years and these remained stable over time. Results indicate age-related and between individual differences on reported OCS that need to be considered for prevention and intervention planning.

Relevance of Five-Factor Model personality traits for obsessive-compulsive symptoms in patients with psychotic disorders and their un-affected siblings

High rates of obsessive-compulsive symptoms (OCS) in schizophrenia require pathogenic explanations. Personality traits may represent risk and resiliency factors for the development of mental disorders and their comorbidities. The aim of the present study was to explore the associations between Five-Factor Model (FFM) personality traits and the liability for OCS in patients with psychotic disorders and in their un-affected siblings. FFM traits, occurrence and severity of OCS and (subclinical) psychotic symptoms were assessed in 208 patients and in 281 siblings. Differences in FFM traits between participants with vs. without comorbid OCS were examined and the predictive value of FFM traits on group categorization was evaluated. Associations between FFM traits and OCS severity were investigated. Patients and siblings with OCS showed significantly higher Neuroticism compared to their counterparts without OCS. Neuroticism was positively associated with higher OCS severity and significantly predicted group assignment in both patients and in siblings. Patients with comorbid OCS presented with lower scores on Extraversion and Conscientiousness. Higher Neuroticism, and to a lesser degree lower Extraversion and Conscientiousness might add to the vulnerability of patients with a psychotic disorder to also develop OCS. Future prospective studies are needed to elucidate proposed personality-psychopathology interrelations and possible mediating factors.

Obsessive compulsive symptom dimensions and neuroticism: An examination of shared genetic and environmental risk

Individuals with obsessive compulsive disorder can display diverse and heterogeneous patterns of symptoms. Little is known about the relationship between obsessive-compulsive symptom (OCS) dimensions and normal personality traits, particularly those that increase risk for other internalizing disorders. In this study of 1,382 individuals from female-female twin pairs, we examined the relationship between self-report OCS dimensions derived from the Padua Inventory and Eysenck's personality traits neuroticism and extraversion. We conducted factor analysis to determine their phenotypic structure followed by twin analyses to determine their genetic and environmental sources of covariation. A three-factor solution, with dimensions corresponding to checking, aggressive obsessions, and contamination, was the best fit for the Padua OCS items. These dimensions were significantly and somewhat variably associated with neuroticism but negligibly associated with extraversion. The genetic correlations between neuroticism and these three OCS dimensions were moderate to high (0.66 with checking, 0.89 with aggressive obsessions, and 0.40 with contamination). However, the estimated genetic correlation between neuroticism and a unified latent OCS construct was smaller (0.32). Overall this study suggests that genetic, and to a smaller extent environmental, factors underlying neuroticism may act differentially as risk factors for OCS dimensions.

The South Korean Twin Registry: An Update

The South Korean Twin Registry (SKTR) is an ongoing nation-wide volunteer registry of South Korean twins and their families, which was established in the year 2001 to understand genetic and environmental etiologies of psychological and physical traits among South Koreans. Recently, the SKTR sampling has been extended in two important ways. First, we began to recruit twins from lower socio-economic families to study interaction effects of gene by environmental context. Second, as a parallel study of the SKTR, the Nigerian Twin and Sibling Registry was developed to understand the origin of the population group differences/similarities in psychological traits between South Koreans and Nigerians. This article summarizes the main findings (based on the SKTR sample to date), recruitment procedures, zygosity assessment, measures, and future plans for the SKTR.

The Frequency and Clinical Significance of Twin Gestations According to Zygosity and Chorionicity

Background:Although the clinical importance of chorionicity in twin pregnancies has been studied widely, the significance of perinatal determination of zygosity using molecular genetic analyses remains controversial. The purpose of this study was to determine the frequency and clinical significance of twin gestations according to zygosity and chorionicity in a Korean population.Methods:We enrolled 569 women who delivered twin newborns (> 24 weeks) at Seoul National University Hospital between 1999 and 2008. Chorionicity was established by histologic examination of placentae. Zygosity was determined with sex of neonates, chorionicity, and DNA analysis of umbilical cord blood.Results:The frequency of dizygotic (DZ) twins was 71.0% (404/569 pairs) based on the opposite sex (238/404 [58.9%]) and DNA analyses (166/404 [41.1%]); that of monozygotic (MZ) twins was 29.0% (165/569), including monochorionic (MC) (72.1% [119/165]) and dichorionic (DC) twins (27.9% [46/165]), which was confirmed by DNA analyses. Among spontaneously conceived twins, the frequency of MZ twins was more than twice that of DZ twins. The risk of low birth weight was 1.8-fold higher among MZDC twins and 1.9-fold higher among MZMC twins than among DZDC twins (p< .05). Bronchopulmonary dysplasia occurred more frequently among MZMC twins than among DZDC twins (adjusted OR 8.42, 95% CI 1.82–39.08,p< .01). However, the frequencies of other neonatal morbidities were not significantly higher in the MZMC group than in the MZDC and DZDC groups. The perinatal mortality rate was 15 per 1000 total births in the DZDC twins, 20 per 1000 total births in the MZDC and 56 per 1000 total births in the MZMC (p< .01).Conclusions:Although monozygosity was shown to be a risk factor for perinatal death and accurate determination of zygosity plays a great role in the future consideration of organ transplantation and twin studies, the value of zygosity determination along with chorionicity in relation to overall neonatal morbidity was not definite.

Etiology of obsessions and compulsions: a meta-analysis and narrative review of twin studies

The relative importance of genetic and environmental factors in the etiology of obsessive-compulsive (OC) symptoms is unclear. Cognitive-behavioral models propose that shared environment (e.g., parenting style) is important. Family segregation studies suggest that nonadditive genetic factors may be involved. To investigate the etiology of OC symptoms, a meta-analysis was conducted of 37 twin samples from 14 studies, supplemented by a narrative review. Results indicated that in terms of mean effect sizes, (a) additive genetic effects and nonshared environment accounted for most of the variance in OC symptoms, (b) shared environment and nonadditive genetic effects made little or no contribution; (c) these findings did not vary with sex or symptom severity; (d) variance due to nonshared environment increased with age; (e) gene-environment interactions play an etiologic role; (f) OC symptoms are shaped by etiologic factors common to all types of OC symptoms but also have symptom-specific etiologies; and (g) OC symptoms are also shaped by very general etiologic factors (e.g., those influencing negative emotionality). Overall, the findings indicate that OC symptoms have a complex etiologic architecture that is not adequately explained by contemporary etiological models.

Should OCD be classified as an anxiety disorder in DSM-V?

In DSM-III, DSM-III-R, and DSM-IV, obsessive-compulsive disorder (OCD) was classified as an anxiety disorder. In ICD-10, OCD is classified separately from the anxiety disorders, although within the same larger category as anxiety disorders (as one of the "neurotic, stress-related, and somatoform disorders"). Ongoing advances in our understanding of OCD and other anxiety disorders have raised the question of whether OCD should continue to be classified with the anxiety disorders in DSM-V. This review presents a number of options and preliminary recommendations to be considered for DSM-V. Evidence is reviewed for retaining OCD in the category of anxiety disorders, and for moving OCD to a separate category of obsessive-compulsive (OC)-spectrum disorders, if such a category is included in DSM-V. Our preliminary recommendation is that OCD be retained in the category of anxiety disorders but that this category also includes OC-spectrum disorders along with OCD. If this change is made, the name of this category should be changed to reflect this proposed change.