Mortality over a 20-year period in patients with primary polydipsia associated with schizophrenia: a retrospective study.

Primary polydipsia, excessive fluid intake without medical cause, is present in over 20% of seriously and persistently ill psychiatric inpatients. The long-term effects of primary polydipsia on longevity have not previously been examined. Inpatients in a psychiatric hospital were screened for polydipsia in 1985.