Neuropsychiatric symptoms and cognitive impairment in idiopathic normal pressure hydrocephalus

Idiopathic Normal Pressure Hydrocephalus (iNPH) is a treatable cause of gait, cognitive and urinary impairment in the elderly. Neuropsychiatric symptoms, particularly depression and apathy, are prevalent in iNPH, but their links to cognitive impairment are underexplored. To investigate this, we recruited 27 people with clinically diagnosed iNPH, 11 with asymptomatic ventriculomegaly (AVIM) and 9 elderly healthy participants. Gait, cognitive and urinary impairment were assessed with the iNPH grading scale (iNPHGS); depression with the PHQ-9; apathy with a PSP-QoL proxy item; and cognition with the ACE-III. Between-group differences were assessed using Wilcoxon tests, and associations using Spearman’s correlation. We found the iNPH group showed significantly greater apathy than AVIM or healthy controls (15/27, 56%, with moderate, marked or extreme symptoms), alongside a high rate of moderate depression (8/26, 31%). Neither symptom correlated with gait impairment, but depression correlated with cognitive impairment with a trend for apathy (depression: ρ=0.63, p=0.002; apathy: ρ=0.42, p=0.059). Of ACE-III domains, visuospatial, language and fluency correlated with depression. Overall, depression and apathy are common in iNPH and depression correlates with cognitive impairment. Further work should investigate a possible shared mechanism underlying neuropsychiatric and cognitive impairment in iNPH, possibly affecting frontal-subcortical networks, and determine whether AVIM patients demonstrate subclinical neuropsychiatric symptoms.