Suchergebnisse

AbstractSpecific environments and social relationships may alter the impact of genes. Previous studies have shown marriage to moderate heritability for depressive symptoms in females, suggesting that marriage provides protection or compensation against genetic risks. Similar mechanisms may be relevant for subjective wellbeing (SWB), which is considerably influenced by genes and almost universally associated with marital status. Questionnaire data on SWB from a population-based sample of 1250 monozygotic (MZ) and 981 dizygotic (DZ) male and female twin pairs (n= 4462) were analyzed using structural equation modeling by means of Mx to investigate genetic and environmental influences on SWB across marital status. Resemblance for SWB in MZ twins exceeded that of DZ twins, but the magnitude of this difference varied across marital status. Genetic factors explained 51% and 54% of the variance in SWB among unmarried males and females, and 41% and 39% in married or cohabitating respondents. Remaining variance was attributable to the nonshared environment. The genetic influences were partly different (rg= 0.64) across marital status in females, but overlapping in married and single males. Our findings show that marriage moderates the magnitude of genetic influences on SWB in both males and females, with a smaller estimate of genetic influences for those with a marital or equivalent partner. The genetic influences on SWB are thus clearly contingent on the environmental context.

AbstractEtiological factors for stability and change in symptoms of anxiety and depression, including sex differences, are largely unexplored in young adults. Using biometric modeling and two-wave longitudinal data from 4393 Norwegian twins aged 18 to 31 we explored (i) heritabilities of symptoms of anxiety and depression, (ii) effects of genetic and environmental factors on the stability and change of such symptoms, and (iii) sex-specific effects. The phenotypic cross-time correlations for symptoms of anxiety and depression were estimated to .54 and .49 for males and females, respectively. The best fitting longitudinal model specified additive genetic and individual environmental influences and emerging effects from the shared environment for females only. For both males and females, long-term stability was mainly attributable to stable additive genetic factors, whereas change was essentially related to environmental influences. Minor time-specific genetic effects were indicated, and some stable variance was due to the individual environment. Additive genetic risk factors explained 87% and 68% of the phenotypic cross-time correlation for males and females, with the unique environment accounting for the remaining covariance. The results provide strong evidence for the temporal stability of genetic risk factors for symptoms of anxiety and depression in young adults, and substantial sex-specific influences on heritability, stability and change.

AbstractThe relationship between subjective wellbeing (SWB) and self-reported sleep problems was investigated in a cohort of Norwegian twins aged 18 to 31 years. Questionnaire data from 8045 same- and opposite-sex twins were analyzed using structural equation modeling to explore the relative effects of genetic and environmental influences on phenotypic variance and covariance. Special attention was paid to sex-specific effects. The correlation between the phenotypes was estimated to be −.43. Univariate analyses indicated considerable genetic influences for both SWB and sleep problems, for male and female twins alike. The best fitting bivariate model specified additive genetic and individual environmental factors for both phenotypes, and nonadditive genetic effects for sleep problems, with no sex-specific effects. Genetic and environmental effects accounted for 60% and 40% of the phenotypic correlation, respectively. Additive genetic factors affecting the two phenotypes were correlated (−.85), suggesting that part of the genetic effects that positively influence SWB also protect against sleep problems. In conclusion, the results indicate considerable overlap in genetic etiology for SWB and sleep problems, for males and females alike.