Risk for affective disorder and alcohol and other drug abuse in the relatives of affectively ill adoptees.

We investigated the risk for substance abuse in the biological relatives of adoptees with affective illness, controlling for potential confounds, and additionally assessed risk by probands' and relatives' gender. Our sample consisted of 67 index adoptees with affective illness, matched control adoptees, and their biological and adoptive relatives. Both affective illness and substance abuse were more common in the biological relatives of affectively ill adoptees than in controls' relatives. Affective illness was more common than substance abuse among female index biological relatives, with the opposite pattern observed among male relatives.