Stressful life events and genetic liability to major depression: genetic control of exposure to the environment?
BACKGROUND
Although overwhelming evidence suggests that genetic and environmental risk factors both contribute to the aetiology of major depression (MD), we know little of how these two risk factor domains inter-relate. In particular, can the genetic liability to MD increase the risk of experiencing stressful life events (SLEs)?


METHODS
Using discrete time survival analysis in a population-based sample of 2164 female twins, we examined whether the risks for nine personal and three aggregate network SLEs were predicted by the level of genetic liability to MD, indexed by the lifetime history of MD in monozygotic and dizygotic co-twins.


RESULTS
Genetic liability to MD was associated with a significantly increased risk for six personal SLEs (assault, serious marital problems, divorce/breakup, job loss, serious illness and major financial problems) and one network SLE (trouble getting along with relatives/friends). This effect was not due to SLEs occurring during depressive episodes. Similar results were found using structural equation twin modelling. In contrast to the pattern observed with MD, the genetic liability to alcoholism impacted on the risk for being robbed and having trouble with the law.


CONCLUSIONS
In women, genetic risk factors for MD increase the probability of experiencing SLEs in the interpersonal and occupational/financial domains. Genes can probably impact on the risk for psychiatric illness by causing individuals to select themselves into high risk environments.
Kendler
K S
KS
Department of Psychiatry, Medical College of Virginia, Richmond, USA.
Karkowski-Shuman
L
L
D000328:Adult; D003866:Depressive Disorder / Q000235:genetics*; D004198:Disease Susceptibility; D005192:Family Health; D005260:Female; D006801:Humans; D008016:Life Change Events; D016013:Likelihood Functions; D008137:Longitudinal Studies; D008954:Models, Biological; D016017:Odds Ratio; D012044:Regression Analysis; D012494:Sampling Studies; D012931:Social Environment; D016019:Survival Analysis