Family factors and child and adolescent depression symptoms: testing environmental and genetic risk effects using longitudinal and genetically sensitive research designs.

Child and adolescent depression is a complex and multifactorial disorder that is likely due to the co-action and interaction of multiple psychosocial and genetic risk factors. Identifying the specific psychosocial factors which confer risk is a paramount aim of depression research since this is essential to informing the design and implementation of preventive interventions. Prior research has suggested that a range of family factors are associated with the development of child and adolescent depression. However, the extent to which these associations are likely to be causal is unclear due to a range of issues such as establishing the direction of effects and estimating the role of potential confounding factors which include genetic influences and alternative psychosocial risks. In this thesis I use different research designs to examine the ‘environmental’ effects of two specific family factors which have established associations with child and adolescent depression symptoms: parent child hostility (study 1) and parent depression (study 2). I also explore whether there is moderation of the putative environmental effects of these family factors by specific gene variants (gene-environment interaction; study 3). The role of both parent and child tender was examined across studies. Using genetically sensitive and longitudinal designs, environmental effects on child and adolescent depression symptoms were detected for mother-child hostility and parent depression. For both family factors, effects appeared to be stronger for girls suggesting their increased susceptibility to these stressors. No evidence of an environment interaction was detected