The relationship of paranoid states to schizophrenia.

The author interviewed relatives of 32 paranoid patients, 32 matched depressed patients, and 15 schizophrenic patients regarding family history. Two (1.3%) of the relatives of paranoid patients and one (0.6%) of the relatives of depressed patients had possible paranoid states. Significantly more relatives of schizophrenic patients than relatives of paranoid or depressed patients had schizophrenia, but the rates were similar among relatives of paranoid and depressed patients. The author concludes that there is little evidence of familial occurrence of paranoid states and no evidence that paranoid states are familially related to schizophrenia.