Beyond depression and dementia: Idiopathic normal pressure hydrocephalus as a neuropsychiatric mimic in the emergency department

Abstract

Background: Idiopathic normal pressure hydrocephalus (iNPH) is a neurological disorder and one of the few potentially reversible causes of dementia and disability in older adults. A recent systematic review and meta-analysis reports that apathy occurs in roughly 69% and depression in about 30% of affected patients. Because these neuropsychiatric manifestations are prominent early, iNPH may be mistaken for a primary psychiatric disorder, sometimes for years. Objective: To equip emergency physicians (EPs) caring for older adults with behavioral or cognitive complaints with a practical framework for recognizing iNPH as a neuropsychiatric mimic, and for trauma-informed assessment of shunt-dependent patients presenting with new psychiatric symptoms. Discussion: Frontal-subcortical circuit dysfunction in iNPH produces apathy, psychomotor slowing, depression, anxiety, and, in a minority of cases, agitation or psychotic phenomena. A 2025 placebo-controlled NEJM trial demonstrated significant gait improvement after shunting. A pooled estimate suggested a modest reduction in depression scores, although its confidence interval included no effect. In emergency settings, brief structured gait assessment combined with explicit screening for apathy versus sadness can help distinguish iNPH from depression and Alzheimer disease. Shunted patients who present with anxiety, hypervigilance, or activity restriction warrant careful, trauma-informed evaluation before a primary psychiatric diagnosis is assumed; their somatic concerns may be valid signals of mechanical malfunction or appropriate responses to permanent device dependence. Conclusions: Older adults presenting to the ED with depression, dementia, or new behavioral symptoms warrant a brief gait examination and a focused review for the iNPH triad. EPs play a pivotal role in recognizing this treatable neurological disorder when neuropsychiatric manifestations dominate the presentation, and in honoring the embodied knowledge of patients living with a permanent intracranial device. The screening approach described here is an expert-derived educational framework that awaits prospective validation.