Neuropsychiatric symptom burden in early‐onset and late‐onset Alzheimer's disease as a function of age.

INTRODUCTION: We examined the burden of neuropsychiatric symptoms (NPSs) in early‐onset (EO) and late‐onset (LO) Alzheimer's disease (AD) and adjusted for age effects via the inclusion of cognitively unimpaired (CU) individuals. METHODS: Cross‐sectional data from 2940 EOAD, 8665 LOAD, and 8775 age‐stratified CU individuals (early‐CU, n = 2433; late‐CU, n = 6342) from the National Alzheimer's Coordinating Center database were included. Fisher's exact tests compared EOAD and LOAD on the presence and severity of NPSs. Multiple logistic regression models included an age*diagnosis interaction to examine age effects. RESULTS: Presence (ps < 0.0001) and severity (ps < 0.05) of NPS were greater in EOAD than in LOAD. However, after adjusting for base rates in NPS in CU individuals (age effects), only elation and eating behaviors were more frequent in EOAD (ps < 0.05) and nighttime behaviors more frequent and severe in LOAD (ps < 0.05). DISCUSSION: Few NPSs were specific to the EOAD versus LOAD. Previous findings of greater NPS burden in EOAD may partially reflect age effects. Highlights: Adjusting for age effect, elation and eating problems are more frequent in EOAD.Adjusting for age effect, sleep disturbances are more frequent and severe in LOAD.Age effects underlie higher neuropsychiatric symptom presentation in EOAD than in LOAD. [ABSTRACT FROM AUTHOR]