Hazard, heredity and depression. A family study.

The relationship between proband characteristics and familial aggregation of depression was assessed in an interview study of 83 families ascertained via probands who had a recent onset of depression. Contrary to expectations and to previous reports in the literature there were no differences between the frequencies of depression in the first degree relatives of probands who had or had not experienced adversity prior to the onset of their illness. Depression was actually slightly more common among the first degree relatives of probands who had experienced a threatening life event compared with the relatives of those who had not. Early onset of depression (before 32 yr) and a neurotic pattern of symptoms in probands were associated with significantly higher rates of current illness in relatives. However, both these differences disappeared when lifetime prevalence or morbid risk to age 65 were considered. Indeed the morbid risk of severe depression in the relatives of endogenously depressed probands was nearly twice that in the relatives of neurotic probands.