Psychiatric resilience: longitudinal twin study.

BACKGROUND The source of variability in people's response to stressful life events is poorly understood. AIMS We examine the genetic and environmental underpinning of resilience (i.e. the difference between the twins' internalising symptoms and their predicted symptoms based on cumulative stressful life events). METHOD Stressful life event exposure and internalising symptoms were assessed at two time points in 7500 adult twins. Using the residual between actual and predicted internalising symptom total score, twin modelling was conducted for each wave separately and longitudinally. RESULTS Resilience was found to have a moderate genetic heritability at each wave (~31%). Qualitative gender effects were found. Incorporating error of measurement into the model increased the estimated heritability for the latent construct of resilience (~50%). When measurement error and occasion-specific effects were removed, environmental influences contributed roughly equally to level of resilience. CONCLUSIONS Both genes and environment influence level of psychiatric resilience, and are largely stable over time. Environmental influences can have an enduring effect on resilience.