Unexplained Coma and Sudden Death in Psychiatric Patients Due to Self-Induced Water Intoxication: Clinical Insights and Autopsy Findings From Two Fatal Cases

Self-induced water intoxication is a life-threatening condition caused by excessive water intake that surpasses renal excretion capacity, resulting in hypotonic hyponatremia. This acute imbalance leads to cerebral and pulmonary edema, neurological deterioration, and potentially fatal outcomes. Psychiatric disorders such as schizophrenia and postpartum psychosis are significant contributors, often driving these behaviors through unique psychopathological mechanisms exacerbated by inadequate patient supervision. This study presents two fatal cases. The first involves a 42-year-old woman with chronic schizophrenia and psychogenic polydipsia, whose condition progressed gradually, allowing partial therapeutic intervention. The second describes a 28-year-old woman with postpartum psychosis and compulsive water drinking linked to religious delusions, whose condition deteriorated rapidly, leading to cardiopulmonary arrest shortly after admission. Both cases highlight the connection between psychiatric disorders and severe hyponatremia (<120 mmol/L), resulting in irreversible brain damage and sudden death. Autopsy findings revealed diffuse cerebral edema, pulmonary congestion, and diffuse axonal injury with reactive astrogliosis, demonstrating the severe impact of electrolyte imbalances on neuronal damage. Neuropathological findings, such as ubiquitin-positive axonal swellings and astrocytic activation, underscore the critical role of ionic homeostasis disruption in bridging clinical and autopsy observations. These cases highlight the importance of early recognition of psychogenic polydipsia and compulsive water-drinking behaviors, particularly in high-risk psychiatric patients. Preventative strategies should include routine electrolyte monitoring, caregiver education, and proactive management of psychiatric disorders. Critically, water intoxication must always be considered among the possible causes of unexplained coma or sudden death in psychiatric patients, stressing the need for clinical vigilance and accurate postmortem assessment to improve prevention.