Continuity of genetic and environmental influences on clinically assessed major depression from ages 18 to 45

Stressful life events exhibit complex patterns of associations with depressive symptoms in two population-based samples using network analysis

BACKGROUND

Stressful life events (SLEs) constitute key risk factors for depression. However, previous studies examining associations between SLEs and depression have been limited by focusing on single events, combining events into broad categories, and/or ignoring interrelationships between events in statistical analyses. Network analysis comprises a set of statistical methods well-suited for assessing relationships between multiple variables and can help surpass several limitations of previous studies.

METHODS

We applied network analysis using mixed graphical models combining two large-scale population-based samples and >34,600 randomly sampled adults to investigate the associations between SLEs and current depressive symptoms in the general population.

RESULTS

Numerous SLEs were uniquely associated with specific symptoms. Strong pairwise links were observed between SLEs during the past year and individual symptoms, e.g., between having experienced illness or injury and sleeping problems, having been degraded or humiliated and feeling blue, and between financial problems and hopelessness and being worried and anxious. Several SLEs, such as financial problems, sexual abuse, and having been degraded or humiliated, were associated with symptoms across more than one timepoint. More recent SLEs were generally more strongly associated with depressive symptoms. Several life events were strongly interrelated, such as multiple forms of abuse, and financial problems, unemployment, divorce, and serious illness or injury.

LIMITATIONS

Limitations include a retrospective SLE measure, cross-sectional data, a brief self-report measure of depressive symptoms, and possible attrition bias in the sample.

CONCLUSIONS

Our findings may have implications for public health efforts seeking to improve population mental health.

Mothers' symptoms of anxiety and depression and the development of child temperament: A genetically informative, longitudinal investigation

Background

Child temperament traits and mothers' emotional symptoms relating to anxiety and depression may drive changes in one another, leading to their 'co-development' across time. Alternatively, links between mother and child traits may be attributable to shared genetic propensities. We explored longitudinal associations between mothers' emotional symptoms and child temperament traits and adjusted for genetic effects shared across generations.

Methods

This study is based on the Norwegian Mother, Father and Child Cohort Study (MoBa). Mothers (n = 34,060) reported on their symptoms of anxiety and depression, and temperament among offspring (n = 42,526), at child ages 1.5, 3 and 5 years. Structural equation models parameterised developmental change in traits, and an extended family design adjusted for genetic effects.

Results

We found individual differences in stable trait scores and rate of change for all study variables. Longitudinal stability in mothers' emotional symptoms was associated with longitudinal stability in offspring emotionality (r = 0.143), shyness (r = 0.031), and sociability (r = -0.015). Longitudinal change in mothers' symptoms showed very small or negligible correlations with longitudinal change in child temperament. Both genetic and environmental influences explained the stable longitudinal association between mothers' symptoms and child emotionality.

Conclusions

The studied associations between mother and child traits across time appeared to be due to stable, trait-like factors, involving genetic and environmental influence, rather than their co-development. Findings contribute knowledge on how emotional symptoms develop in families across time, and the methods with which we can explore such development.

Kind of blue - An evaluation of etiologies for prenatal versus postnatal depression symptoms

BACKGROUND

Prenatal and postnatal depression potentially have severe consequences, but we do not know to what extent they have the same etiological factors. Genetically informative designs yield insight into common etiology between pre- and postnatal depression and inform on potential prevention and intervention efforts. This study evaluates the overlap in genetic and environmental factors in pre- and postnatal depression symptoms.

METHODS

We conducted univariate and bivariate modeling, using a quantitative, extended twin study. The sample was a subsample of the MoBa prospective pregnancy cohort study in 6039 pairs of related women. Measurement was conducted at week 30 of pregnancy and 6 months following delivery, using a self-report scale.

RESULTS

The heritability of depressive symptoms was 16.2 % (95 % CI = 10.7-22.1) prenatally and 25.7 % (95 % CI = 19.2-32.2) postnatally. The correlation between risk factors for prenatal and postnatal depressive symptoms was at unity (r = 1.00) for genetic effects, and at disunity (r = 0.36) for environmental effects. The genetic effects for postnatal depressive symptoms were 1.7 times larger compared to prenatal depressive symptoms.

LIMITATIONS

Although genes for depression become more influential postpartum, only future studies can inform on the mechanisms for such a socio-biological augmentation of effect.

CONCLUSION

Genetic risk factors for prenatal and postnatal depressive symptoms are indistinguishable in kind, with greater impact after birth, whereas environmental risk factors for depression symptoms are mostly non-overlapping before and after birth. These findings indicate that interventions could be of different kind before and after birth.

Genetic and environmental contributions to psychopathological symptoms stability and change across the COVID-19 pandemic

Several longitudinal studies investigated changes in mental health related to the pandemic event. However, little research has focused on the mediating role of environmental and genetic factors. The current prospective study aimed to evaluate the genetic and environmental contributions to the stability of symptoms of depression, anxiety and stress during the COVID-19 crisis. A total of 798 adult twins, previously enrolled in the Italian Twin Register, participated in the study and completed on-line questionnaires sent out on June 2020 and December 2020. The nine-item Patient Health Questionnaire (PHQ-9), the six-item State-Trait Anxiety Inventory (STAI-6), and the Impact of Event Scale - Revised (IES-R) were administered to assess depressive and anxiety symptoms, and pandemic-related subjective distress, respectively. A considerable longitudinal stability was observed for each trait (range: 0.57, STAI-6 - 0.67, PHQ-9). Bivariate Cholesky decomposition indicated that genetic factors explained from 53% (IES-R) to 61% (STAI-6) of between-wave covariance and that genetic overlap between the two waves was almost complete (range: 0.91, STAI-6 - 0.99, PHQ-9). Our findings support the hypothesis, at least over the 6-month period examined, of a genetic stability between waves and of an environmental discontinuity due to changes in life conditions during the pandemic.