Background. Although overwhelming evidence suggests that
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
predicted by the level of genetic liability to MD, indexed by the lifetime
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
This effect was not due to SLEs occurring during depressive episodes. Similar
found using structural equation twin modelling. In contrast to the pattern
with MD, the genetic liability to alcoholism impacted on the risk for being
robbed and having trouble with the law.
Conclusion. In women, genetic risk factors for MD increase
probability of experiencing
SLEs in the interpersonal and occupational/financial domains. Genes
probably impact on
the risk for psychiatric illness by causing individuals to select themselves
into high risk environments.