Behavioral and psychological subsyndromes in Alzheimer's disease using the Neuropsychiatric Inventory

Objective Behavioral and psychological symptoms of dementia represent common clinical features of dementias, contributing to the heterogeneous phenotypic expression of Alzheimer's disease (AD). During the last two decades, several studies explored the possible presence of neuropsychiatric subsyndromes in dementia by examining the internal structure of the Neuropsychiatric Inventory (NPI). The aim of the present review is to present available evidence coming from studies adopting factor analysis to explore the NPI and describe neuropsychiatric clusters of symptoms in AD. Design A systematic review of literature was performed concerning available studies describing neuropsychiatric subsyndromes in AD by adopting the NPI. Results Overall, our analysis showed a relatively low concordance among available evidence for what concerns the definition and composition of NPI clusters, possibly due (at least in part) to the heterogeneity of the sample populations recruited in the studies. However, we also observed some consistent associations of specific symptoms across studies, defining potential subsyndromes in AD. More consistent results were obtained by studies evaluating the 10-item version of the NPI rather than the more recent 12-item one. Conclusions This review represents the first attempt to systematically evaluate evidence coming from factor analyses exploring the internal structure of the NPI in order to facilitate the identification of neuropsychiatric syndromes in AD patients. The NPI may support the definition of behavioral subsyndromes in AD. The evaluation of neuropsychiatric subsyndromes should always take into account the main potential confounders, such as age, severity of disease, and concomitant pharmacological treatment.