Polydipsia, psychosis, and familial psychopathology

To compare the demographic and clinical factors and familial psychopathology of chronic psychiatric inpatients with, and without, polydipsia.

We undertook a case-control study of chronic psychiatric inpatients both with, and without, polydipsia. Clinical and demographic data were gathered using a predesigned questionnaire, the Positive and Negative Syndrome Scale (PANSS), the Abnormal Involuntary Movement Scale (AIMS), the Mini-Mental State Examination Scale (MMSE), and the Family History-Research Diagnostic Criteria (FH-RDC).

The prevalence rate of polydipsia was 20.2%. The group with polydipsia was significantly younger, both at the time of their first-ever psychiatric and current psychiatric admissions, compared with the group without polydipsia. The 2 groups were similar in terms of their illness characteristics and psychiatric diagnoses. In the group with polydipsia, alcohol abuse predated the psychotic illness by a mean of 10.5 (SD 4.4) years, compared with 4.8 (SD 1.6) years for the same period in the unaffected group. The 2 groups did not differ significantly regarding the antipsychotic medication dosage, the proportion on concomitant anticholinergic medication, the documented previous response to antipsychotic medication, or past treatment with electroconvulsive therapy (ECT). First-degree relatives of patients with polydipsia were found to have significantly higher rates of alcohol dependence.

This study provides further evidence for the higher rate of polydipsia among chronic psychiatric patient populations and for high rates of alcohol-related problems among their first-degree relatives.