Risk of idiopathic normal pressure hydrocephalus in older inpatients with schizophrenia

Background: The mean age of inpatients with schizophrenia has gradually increased in Japan and the risk of fracture in older schizophrenia patients is elevated. One possible cause may be idiopathic normal pressure hydrocephalus (iNPH). The present study aimed to evaluate the prevalence and symptoms of iNPH in older inpatients with schizophrenia. Methods: We prospectively examined older inpatients with schizophrenia (N = 21, mean age = 70.5 +/- 5.9) in a psychiatric ward. We evaluated iNPH symptoms using the idiopathic Normal-Pressure Hydrocephalus Grading Scale (iNPHGS), Timed Up-and-Go test (TUG), Gait Status Scale (GSS), Mini-Mental State Examination (MMSE), and Neuropsychiatric Inventory (NPI). We also evaluated symptoms of schizophrenia using the Brief Psychiatric Rating Scale (BPRS) and Drug-Induced Extrapyramidal Symptoms Scale (DIEPSS). We conducted cerebrospinal fluid (CSF) tap tests for patients with possible-iNPH. Results: In total, three (14.3%) patients were diagnosed with possible iNPH: age, GS-Gait, GS-Cognition, TUG, 10-meter walking test, GSS, and DIEPSS were significantly increased in these compared to patients without iNPH; however, GS-Urine, MMSE, NPI, and BPRS did not differ significantly. Probable iNPH was diagnosed for two (9.5%) patients because of positive CSF tap tests. Conclusion: The prevalence of possible and probable iNPH in older patients with schizophrenia was much higher than that reported for older people without mental illness. Of the symptoms evaluated with the tests employed, only gait disturbances, particularly walking speed, distinguished schizophrenia patients with iNPH. These findings suggest that we should pay more attention to the possibility of iNPH in older patients with schizophrenia.