Evidence for genetic inheritance of primary affective disorder in adoptees

Offspring of psychiatrically disturbed and normal biologic parents, adopted away at birth, were followed up as adults. The psychiatric status of the adoptees was determined by adoptive parent and adoptee interviews. The incidence of depression was significantly higher in the affective-parented adoptees (3 depressed of 8 adoptees) than in the remaining adoptees whose biologic parents had other psychiatric conditions or were apparently psychiatrically well (8 depressed of 118). The results suggest a genetic factor in affective disorders.