Childhood Adoption and Mental Health in Adulthood: The Role of Gene-Environment Correlations and Interactions in the UK Biobank

Abstract

BACKGROUND: Being adopted early in life, an indicator of exposure to early-life adversity, has been consistently associated with poor mental health outcomes in adulthood. Such associations have largely been attributed to stressful environments, e.g., exposure to trauma, abuse, or neglect. However, mental health is substantially heritable, and genetic influences may contribute to the exposure to childhood adversity, resulting in potential genetic confounding of such associations. METHODS: Here, we explored associations between childhood adoption and mental health-related outcomes in midlife in 243,797 UK Biobank participants (n adopted = 3151). We used linkage disequilibrium score regression and polygenic risk scores for depressive symptoms, schizophrenia, neuroticism, and subjective well-being to address potential genetic confounding (gene-environment correlations) and gene-environment interactions. As outcomes, we explored depressive symptoms, bipolar disorder, neuroticism, loneliness, and mental health-related socioeconomic and psychosocial measures in adoptees compared with nonadopted participants. RESULTS: Adoptees were slightly worse off on almost all mental, socioeconomic, and psychosocial measures. Each standard deviation increase in polygenic risk for depressive symptoms, schizophrenia, and neuroticism was associated with 6%, 5%, and 6% increase in the odds of being adopted, respectively. Significant genetic correlations between adoption status and depressive symptoms, major depression, and schizophrenia were observed. No evidence for gene-environment interaction between genetic risk and adoption on mental health was found. CONCLUSIONS: The association between childhood adoption and mental health cannot fully be attributed to stressful environments but is partly explained by differences in genetic risk between adoptees and those who have not been adopted (i.e., gene-environment correlation).

Polygenic prediction of PTSD trajectories in 9/11 responders

“…Third, we did not investigate the interaction between genetic vulnerability and trauma exposure severity (gene–environment interaction). While of interest to the field, this research question has led to notable non-replications (Assary et al, 2018; Lehto et al, 2019), including no meta-analytic evidence for the interaction between Depression-PRS and childhood trauma (Peyrot et al, 2018). We were also underpowered to detect very small effect sizes.…”

Schizophrenia polygenic risk is associated with child mental health problems through early childhood adversity: evidence for a gene–environment correlation

“…Only a few studies have employed schizophrenia polygenic risk scores to study the possibility of such gene-environment correlations. Increased schizophrenia polygenic risk has been associated with higher paternal age [18], increased likelihood to be adopted [19], and more bullying victimisation [20], each of which is suggestive of a gene-environment correlation [16,21]. Moreover, a recent study found an association between schizophrenia polygenic risk and exposure to trauma in childhood [22], but the extent to which exposure to adversity explains the relationship between schizophrenia liability and mental health problems remains to be further explored.…”

Fast Feet Forward: Early intervention protocol using bilateral movements to reduce stress and increase positive cognitions in adopted children with complex trauma presentation

“…For example, Lehto et al. (2020) found that whilst adoptees were found to have worse outcomes across mental health domains, they also displayed a greater genetic predisposition for mental health difficulties. This therefore highlights the complex interactions between genetic risk and environmental factors.…”

“…Additionally, although ACEs are a helpful framework to assess the impact of one's environment on psychological and emotional well-being, stressful environments do not fully explain the link between adoption and mental health. For example, Lehto et al (2020) found that whilst adoptees were found to have worse outcomes across mental health domains, they also displayed a greater genetic predisposition for mental health difficulties. This therefore highlights the complex interactions between genetic risk and environmental factors.…”