Stressful life events and affective illness
Abstract:Brostedt EM, Pedersen NL. Stressful life events and affective illness.
Acta Psychiatr Scand 2003: 107: 208–215. © Blackwell Munksgaard 2003. Objective:
To investigate the association between the occurrence of affective illnesses and the number/type of experienced negative stressful life events in a twin material. A case–control study with an unrelated twin as control to the case and a co-twin control study were both undertaken with the same material. Method:
Postal questionnaire responses were used for confirming diagnosis and to inventory stressful life events. Risk ratios (RR) for groups of events were calculated using conditional logistic regression. Results:
A dose–response relationship was observed for the association between stressful life events and affective illness. The RRs for specific groups of exposures were higher in the co-twin control study and higher for dizygotic twin pairs than for monozygotic twin pairs. Conclusion:
Individuals with a history of affective illness select themselves into high-risk environments, in part due to their genetic propensity to the disease. Thus, the association represents a classic genotype–environment correlation.