Polydipsia in chronic psychiatric patients: therapeutic trials of clonidine and enalapril.

A six month long double-blind, placebo-controlled, crossover design pharmacological study was conducted on 14 chronically psychotic, institutionalized patients who suffered from chronic water abuse ("psychogenic polydipsia"). Effects of clonidine and enalapril administered separately and individually were assessed for possible beneficial effects on both physiological parameters such as diurnal weight gain, urine output, and serum sodium levels and on signs of delirium as measured by neurobehavioral testing. Improvement, particularly in tests reflecting fluid consumption, was found with either or both drugs in approximately 60% of test subjects, although no behavioral improvement was demonstrated. As a result of evidence for delayed and carry-over effects the authors recommend that future studies employ phases longer than one month and/or include washout periods.