Neuropsychiatric symptoms in patients with dementia and the longitudinal costs of informal care in the Cache County population

Introduction: Severity of dementia and neuropsychiatric symptoms contribute to increasing informal care costs. We examined which neuropsychiatric symptoms subdomains (NPS-SD) were associated with informal costs in a population-based sample. Methods: Dementia progression and informal costs (2015 dollars) were estimated from the Cache County Dementia Progression Study. Overall NPS and specific NPS-SD were assessed with the Neuropsychiatric Inventory. Generalized Estimating Equations (GEE with gamma-distribution/log-link) modeled the relationship between NPS-SDs and informal cost trajectories. Results: Two hundred eighty participants (52.1% female; age M=85.67, SD=5.60) exhibited an adjusted cost increase of 5.6% (P=.005), 6.4% (P<.001), 7.6% (P=.030), and 13% (P=.024) for every increasing Neuropsychiatric Inventory unit in psychosis-SD, affective-SD, agitation/aggression-SD, and apathy-SD, respectively. An increase in each unit of apathy was associated with a 2% annual decrease in costs (P=.040). Discussion: We extend our prior work on informal costs and dementia severity by identifying NPS-SD associated with informal costs. Interventions targeting NPS-SD may lower informal costs. (C) 2019 The Authors. Published by Elsevier Inc. on behalf of the Alzheimer's Association.