• Depression spectrum disease has been defined as an illness in which a first-degree family member has alcoholism and/or antisocial personality. Pure depressive disease may be considered as the remainder of the depressive illnesses or more rigorously as depression in a person who has a family history of depression but no alcoholism.
Evidence is presented that the course of the illness is different in the two groups. Depression spectrum disease is more variable, with more personality problems and interpersonal conflict. Preliminary data indicate that depression spectrum disease may be linked to such genetic markers as C3 or α-haptoglobin.