Familial (genetic) subtypes of pure depressive disease.

The author reviewed data from five studies and found that depressed patients with a history of depression in a parent or child have more sibships containing depression than depressed patients without this family history. Thus, there is a clustering of depressions in certain families. Sporadic pure depressive disease (PDD), where no depressive illness exists in a first-degree family member of a depressed proband, is associated with a later age of onset than familial PDD, where depressive illness does exist in a first-degree relationship. The possibility exists that familial PDD and sporadic PDD are autonomous illnesses. The presence of a family history of depression may be predictive to some extent of a good response to adequate tricyclic medication or ECT.