Neuropsychiatric symptoms in nursing home patients: factor structure invariance of the Dutch nursing home version of the neuropsychiatric inventory in different stages of dementia

BACKGROUND/AIMS: To examine the influence of dementia stage and psychoactive medication use on the factor structure of the Neuropsychiatric Inventory-Nursing Home version (NPI-NH) in Dutch nursing home patients. METHODS: The NPI-NH was administered to a large sample of 1,437 patients with mild to severe dementia receiving nursing home care. Exploratory factor analysis was used to examine behavioural dimensions underlying neuropsychiatric symptoms indicated by the NPI-NH across dementia stages (as assessed with the Global Deterioration Scale - GDS) and in patients with or without psychoactive medication prescribed. RESULTS: In GDS stages 4/5, 6 and 7, a 4- or 5-factor solution was found, with factors referred to as agitation/aggression, depression, psychosis, psychomotor agitation and apathy. These symptom clusters were replicated in the group of drug-naive patients, but only partially in the group of patients on psychoactive medication. CONCLUSION: The factor structure of the NPI-NH in nursing home patients is consistent with the clinical taxonomy of symptoms, is relatively stable across dementia stages, and is only moderately influenced by psychoactive medication use. The division of depression and apathy into separate behavioural dimensions - also in patients with severe dementia - may have important therapeutic consequences.