Psychiatric disorders in the families of borderline patients.

The prevalence of psychiatric disorders was studied among the families of hospitalized borderline patients, defined by Gunderson and Singer's criteria, and compared with the families of schizophrenic and depressed control patients. Among borderline probands, 38.3% have a first-degree relative with depression, 25.5% had one with pathological mood swings, and 23.4% had one with "eccentric or peculiar behavior." There was no significant increase in the prevalence of schizophrenia among the relatives of borderline patients. Depression was more prevalent in the families of schizotypal borderlines compared with unstable or mixed-pattern patients. There were no schizophrenic diagnoses among the impaired relatives of schizotypal borderlines. A relationship is suggested between affective disorder and criteria-defined borderline disorders.