Neuropsychiatric symptom profile in neurocognitive disorders and their relationship with functional decline

Neuropsychiatric symptoms (NPS) are common in neurocognitive disorders (NCD) and are known to negatively impact patient's functional abilities. However, our understanding of the relationship between individual NPS and functional decline in patients with NCD across the spectrum of cognitive impairment is limited. Here we examine the relationship between specific NPS to characterize their effects on patient's function within and across different etiologies.

Longitudinal observational study using the National Alzheimer's Coordinating Center Uniform Data Set (NACCUDS). We examined NPS as characterized by expert clinicians and report its impact on the outcome of functional decline, measured by the Functional Assessment Questionnaire (FAQ), a standardized assessment of activities of daily living, by dementia etiology (Alzheimer's disease (AD, N = 11,044), Lewy Body Disease (LBD, N = 921), and behavioral variant frontal temporal lobe dementia (bvFTD, N = 933)).

We find apathy was the most commonly endorsed and the most persistent symptom across dementia types in all groups and was associated with more rapid functional decline in AD and bvFTD. On the contrary, depression, occurring in 40% or more of all groups, was not associated with worsening functional impairment in any group. We identified patterns that indicated higher rates of disinhibition and persistent disinhibition in bvFTD compared to AD and LBD. Psychosis had unique impact on functional decline in AD and LBD as did agitation in AD.

Differential impact of individual NPS across dementia etiologies and their impact on functional decline may have important consequences for clinical trial designs for the treatment of these symptoms.