Genetic Factors Underlie Stability of Obsessive–Compulsive Symptoms

The contribution of genetic and environmental factors to the stability of obsessive-compulsive (OC) symptoms has not yet been established in adult population based samples. We obtained the Young Adult Self Report Obsessive-Compulsive Subscale in mono- and dizygotic twins from the population-based Netherlands Twin Register in 1991, 1995 and 1997 and the Padua Inventory Revised Abbreviated in 2002. Stability of OC symptoms was analyzed as a function of genetic and environmental components. Heritability of OC behavior was around 40% at each time-point, independent of the instrument used. OC behavior was moderately stable with correlations ranging between r = .2 (for 11-year intervals), .4 (for 4-5 year intervals) and .6 (for 2 year intervals). Genetic correlations across time were higher, varying between .4 and .9, indicating that the stability of OC symptoms is mainly due to stable genetic factors. This study showed a moderate heritability and stability for OC behavior in adults. Genetic stability across time is high

Genetic and environmental influences on obsessive-compulsive symptoms in adults: A population-based twin-family study

Background. The contribution of genetic factors to obsessive-compulsive (OC) symptoms has not been examined using a large population-based sample of adults. Furthermore, the extent to which there are qualitative and quantitative differences in genetic architecture between men and women with OC symptoms has not been elucidated. Method. We obtained the Young Adult Self Report Obsessive-Compulsive Scale (YASR-OCS) from a group of 5893 monozygotic (MZ) and dizygotic (DZ) twins, and 1304 additional siblings from the population-based Netherlands Twin Register. Structural equation modelling was used to decompose the variation in OC behaviour into genetic and environmental components and analyse quantitative and qualitative sex differences. Results. Familial resemblance was the same for DZ twins and non-twin siblings, which means that there was no evidence for a special twin environment. The same genetic risk factors for OC behaviour were expressed in men and women. Depending on the choice of fit index, we found small (39% for men and 50% for women) or no sex differences (47% for both men and women) in heritability. The remaining variance in liability was due to individual-specific environment. Conclusions. OC behaviour showed a moderate heritability. At most, small quantitative sex differences were found in the genetic architecture of OC behaviour, and no qualitative sex differences

Genetic and Environmental Contributions to Self-Report Obsessive-Compulsive Symptoms in Dutch Adolescents at Ages 12, 14, and 16

Objective: To determine the contributions of genetic and environmental influences to variation in self-report of obsessive-compulsive (OC) symptoms in a population-based twin sample of adolescent boys and girls. Method: Self-report ratings on the eight-item Youth Self-Report Obsessive-Compulsive Scale were collected in Dutch mono- and dizygotic twin pairs who participated at age 12 (N = 746 twin pairs), 14 (N = 963 pairs), or 16 years (N = 1,070 pairs). Structural equation modeling was used to break down the variation in liability to OC symptoms into genetic and environmental components. Results: At age 12, no difference in prevalence was found for OC symptoms in boys and girls. At ages 14 and 16, the prevalence was higher in girls. At all ages, genetic factors contributed significantly to variation on OC symptom liability; 27% at the age of 12, 57% at the age of 14, and 54% at the age of 16. There were no sex differences in heritability. Only at age 12, environmental factors shared by children from the same family contributed significantly (16%) to individual differences in OC symptom scores. Conclusions: During adolescence, OC symptoms are influenced by genetic and nonshared environmental factors. Sex differences in prevalence, but not heritability, emerge in adolescence. At age 12, shared environmental factors are of importance, but their influence disappears at later ages. This is in line with earlier research at age 12 that used parental ratings of OC symptoms. Thus, between-family factors play a significant role in explaining individual differences in OC symptoms at this age. ©2008 by the American Academy of Child and Adolescent Psychiatry