Ragnhild Bang Nes

Subjective well-being : genetic and environmental contributions to stability and change

BACKGROUND Previous cross-sectional studies have found substantial genetic influences on individual variation in subjective well-being (SWB), and evidence for sex-specific genetic effects has been reported. However, the genetic and environmental influences on stability and change in SWB over time are largely unexplored. METHOD Questionnaire data on SWB from a population-based sample of Norwegian twins born 1967 to 1979, initially surveyed in 1992 (T1) and re-surveyed in 1998 (T2), were analysed using structural equation modelling to explore the relative effects of genetic and environmental influences on phenotypic stability and change. RESULTS The phenotypic cross-time correlations for SWB were 0.51 and 0.49 for males and females respectively. The best-fitting longitudinal model specified only additive genetic and individual environmental effects with qualitative and quantitative sex-specific genetic influences. For both males and females, the additive genetic factors influencing SWB were largely stable, although some time-specific genetic contributions were indicated. Cross-time correlations for genetic effects were 0.85 and 0.78 for males and females respectively. The individual environmental influences were primarily time-specific. Additive genetic effects explained approximately 80% of the phenotypic cross-time correlation. For females, the magnitude of the additive genetic effects decreased significantly from T1 to T2, whereas for males, the estimates generally remained unchanged. CONCLUSIONS For both males and females, long-term stability of SWB was mainly attributable to stable additive genetic factors, whereas susceptibility to change was mostly related to individual environmental factors. However, both stable environmental contributions and emerging genetic influences were indicated.

Major depression and life satisfaction: A population-based twin study

BACKGROUND The extent to which positive and negative indicators of mental health share etiological influences has been studied to a limited degree only. This study examines the genetic and environmental influences on association between liability to lifetime DSM-IV Major Depressive Disorder (MDD) and dispositional life satisfaction (LS). METHODS Two-wave questionnaire data on LS (assessed 6 years apart) and lifetime MDD obtained by structured clinical interviews in a population-based sample of adult twins were analysed using structural equation modelling in Mx. RESULTS The prevalence of lifetime MDD was estimated to be 11.1% and 15.8% in males and females, respectively. Individuals fulfilling the criteria for MDD reported significantly lower levels of LS. The co-variation in MDD and dispositional LS was found to be accounted for by genetic and unique environmental influences only. The phenotypic correlation was estimated to be 0.36, of which genetic influences accounted for 74% and environmental factors the remaining 26%. The correlation between genetic factors for MDD and LS was estimated to be -0.55 and the correlation between unique environmental factors to be -0.22. Heritability was estimated to 0.34 and 0.72 for MDD and LS, respectively. LIMITATIONS The sample consists of twins only and there are limitations associated with the twin design. CONCLUSIONS Whereas genetic influences on vulnerability to lifetime MDD are considerably shared with liability to (low) LS, environmental influences are more distinct. Thus, environmental factors associated with risk of MDD do not strongly impact on dispositional LS, and conversely, environmental factors influencing dispositional LS do not strongly buffer against MDD.

Well-being and ill-being: shared environments, shared genes?

The nature of the associations between life satisfaction, anxiety, and depression remains elusive. Using questionnaire data from a large population-based sample (N = 6326) of young adult Norwegian twins (aged 18–31 years) we explored the extent to which latent genetic and environmental factors are (1) common or distinct, and (2) sex-specific. Phenotypic correlations ranged between 0.44 and 0.70 in females, and between 0.41 and 0.69 in males. Environmental influences accounted for 75% of these correlations in females, and less than 50% in males. Genetic and environmental sources of life satisfaction, symptoms of anxiety, and symptoms of depression were shared mostly, but the magnitude of the effects was different in males and females. In both sexes, however, aetiological factors enhancing life satisfaction were simultaneously protecting against feelings of sadness and displeasure, but contributed less to countervailing anxiety and tension.

Subjective Wellbeing and Sleep Problems: A Bivariate Twin Study

The 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.

Erratum to: The relationship between negative life events, psychological distress and life satisfaction: a population-based study

Purpose Negative life events may increase psychological distress and reduce life satisfaction (LS). This study investigates associations between negative life events and both positive and negative indicators of mental health and explores the extent to which these associations are buffered by sense of mastery and perceived social support.

Adaptation to the birth of a child with a congenital anomaly: a prospective longitudinal study of maternal well-being and psychological distress.

This study explores the stability and change in maternal life satisfaction and psychological distress following the birth of a child with a congenital anomaly using 5 assessments from the Norwegian Mother and Child Cohort Study collected from Pregnancy Week 17 to 36 months postpartum. Participating mothers were divided into those having infants with (a) Down syndrome (DS; n = 114), (b) cleft lip/palate (CLP; n = 179), and (c) no disability (ND; n = 99,122). Responses on the Satisfaction With Life Scale and a short version of the Hopkins Symptom Checklist were analyzed using structural equation modeling, including latent growth curves. Satisfaction and distress levels were highly diverse in the sample, but fairly stable over time (retest correlations: .47-.68). However, the birth of a child with DS was associated with a rapid decrease in maternal life satisfaction and a corresponding increase in psychological distress observed between pregnancy and 6 months postpartum. The unique effects from DS on changes in satisfaction (Cohens d = -.66) and distress (Cohens d = .60) remained stable. Higher distress and lower life satisfaction at later assessments appeared to reflect a persistent burden that was already experienced 6 months after birth. CLP had a temporary impact (Cohens d = .29) on maternal distress at 6 months. However, the overall trajectories did not differ between CLP and ND mothers. In sum, the birth of a child with DS influences maternal psychological distress and life satisfaction throughout the toddler period, whereas a curable condition like CLP has only a minor temporary effect on maternal psychological distress.

Well-Being: Heritable and Changeable

Well-being has been found to be heritable and changeable. How do these pieces of evidence fit together? Intuitively, models of change and models of genetic influences may seem contradictory and paradoxical. In this chapter, we aim to unite these findings into an integrated understanding of human happiness. We start out by briefly reviewing some of the current evidence of temporary and lasting change in well-being from different strands of research. Second, we present the main methods of contemporary genetically informative studies and review key findings from this research on well-being. The concept of heritability is thoroughly discussed and central misunderstandings, criticism, and caveats of genetically informative studies addressed. Finally, we present some thoughts toward an integrative model of genes, environment, stability, and change. Genetics is highly likely to facilitate development of increasingly successful tailored interventions, and we propose a notion of positive gene-environment interplay as one path toward increased and sustained happiness.

Mates and marriage matter: genetic and environmental influences on subjective wellbeing across marital status.

Specific 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 (r(g) = 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.

Maternal Sick Leave Due to Psychiatric Disorders Following the Birth of a Child With Special Health Care Needs

Objective Child-related stress following the birth of a child with special health care needs (SHCN) can take a toll on parental health. This study examined how the risk of sick leave due to psychiatric disorders (PD) among mothers of children with SHCN compares with that of mothers of children without SHCN during early motherhood. Methods Responses from 58,532 mothers participating in the Norwegian Mother and Child Cohort Study were linked to national registries and monitored for physician-certified sick leave from the month of their child’s first birthday until the month of their child’s fourth birthday. Results As compared with mothers of children without SHCN, mothers of children with mild and moderate/severe care needs were at substantial risk of a long-term sick leave due to PD in general and due to depression more specifically. Conclusions Extensive childhood care needs are strongly associated with impaired mental health in maternal caregivers during early motherhood.

Genetics, personality and wellbeing. A twin study of traits, facets and life satisfaction

Human wellbeing is influenced by personality traits, in particular neuroticism and extraversion. Little is known about which facets that drive these associations, and the role of genes and environments. Our aim was to identify personality facets that are important for life satisfaction, and to estimate the contribution of genetic and environmental factors in the association between personality and life satisfaction. Norwegian twins (N = 1,516, age 50–65, response rate 71%) responded to a personality instrument (NEO-PI-R) and the Satisfaction With Life Scale (SWLS). Regression analyses and biometric modeling were used to examine influences from personality traits and facets, and to estimate genetic and environmental contributions. Neuroticism and extraversion explained 24%, and personality facets accounted for 32% of the variance in life satisfaction. Four facets were particularly important; anxiety and depression in the neuroticism domain, and activity and positive emotions within extraversion. Heritability of life satisfaction was 0.31 (0.22–0.40), of which 65% was explained by personality-related genetic influences. The remaining genetic variance was unique to life satisfaction. The association between personality and life satisfaction is driven mainly by four, predominantly emotional, personality facets. Genetic factors play an important role in these associations, but influence life satisfaction also beyond the effects of personality.