According to several authors, water intoxication can lead to irreversible brain damage and could be the cause of nearly a fifth of the deaths of schizophrenic patients below the age of 53 years. The aim of our study was first to determine the prevalence of polydipsia and water intoxication in a population of psychiatric inpatients of a well-defined French geographic area (the Somme), and secondly to determine the clinical and socio-demographic factors associated with this disorder.

A cross-sectional survey was done on the 450 psychiatric beds whose catchment area had a total population of 559,429 inhabitants. Using staff reports and patients’ charts, the drinking habits of 353 psychiatric inpatients hospitalised during the survey in the 450 psychiatric beds of this area were examined.

Thirty-eight patients (10.76%; 95% confidence interval: 7.53–13.99%) among the 353 inpatients were polydipsic. About one-third of these patients were at risk of water intoxication. Polydipsia appeared to be significantly associated with male gender, smoking, celibacy and chronicity. The polydipsic patients presented also a high prevalence of schizophrenia, mental retardation, pervasive developmental disorders and high frequency of somatic disorders.

Psychogenic Polydipsia is defined as the desire to drink liquid in big quantities with an inappropriate activation of the mechanisms of thirst without loss of liquid for urine. This disorder is frequent enough and can derive in a water poisoning, a clinical presentation of high mortality.

Review of the Psychogenic Polydipsia in patients with schizophrenia and theoretical discussion of a case report.

A case report of a 58-year-old male, admitted in hospital with a clinical presentation of hyponatremia with severe low serum osmolarity secondary to Psychogenic Polydipsia. As psychiatric history he has a diagnosis of Paranoid Schizophrenia for forty years in treatment with Paliperidone 6 mg: 1-0-0, Haloperidol 10 mg: 0-0-0.5, Quetiapina 300 mg: 0-0-1, Trazodona 100 mg: 0-0-1, Ketazolam 30 mg: 0-0-1, Diazepam 10 mg: 0-0-1.

Psychogenic Polydipsia is not included in any section of current psychiatric classifications as specific diagnosis. There are several psychiatric disorders that may present with psychogenic polydipsia; however, the most common cause appears to be schizophrenia.

Mechanisms of hyponatremia in patients with schizophrenia are not well clarified; nevertheless, dopamine seems to be the common link between psychogenic polydipsia and schizophrenia.

The authors have not supplied their declaration of competing interest.