The genetics of depressive disorders

Abstract

Twin family and adoption studies confirm a genetic contribution to the aetiology of depression which is greater in bipolar compared to unipolar disorder. The evidence suggests that depression is caused by multiple genes and that these confer a susceptibility to develop the disorder. Data from various twin studies can be applied to a liability threshold model which allow the variance contributed to by genetic and environmental aetiological factors to be determined. The few studies that have examined both genetic and environmental risk factors such as threatening life events in the same subjects have indicated that reactions to such events may also be genetically determined. Thus the relationship between environmental and familial aetiological factors is more complex than originally thought.