Comparing behavioral and psychological symptom structures on the Neuropsychiatric Inventory Questionnaire

The Neuropsychiatric Inventory Questionnaire (NPI-Q) is a collateral-rated measure of behavioral and psychological symptoms commonly found in dementia (BPSD). Several factor structures have been published, but they have not been systematically compared. Furthermore, the possibility of hierarchical models or presence of measurement invariance around cognitive stage or dementia syndrome has not been previously evaluated. This study addressed these gaps with confirmatory factor analyses using a multicenter sample (n = 41,801; M_age = 71.4; 57% women; 79% White, 13% Black, 8% Hispanic; M_education = 15.1) that was divided into exploratory, derivation, and holdover subsets for cross-validation. We found that a four-factor model had the best fit, with adequate reliability estimates, adequate τ-equivalence, and the least amount of measurement variance. Strict invariance across stage and syndrome was not supported, although there was adequate support for weaker restrictions (e.g., equal forms). Furthermore, all bifactor models had a significant increase in fit. In sum, the present study provides practical guidance on using NPI-Q factor-derived subscales and theoretical elaboration of BPSD's hierarchical and syndrome-variant structure. (PsycInfo Database Record (c) 2023 APA, all rights reserved).