Neuropsychiatric symptoms and the outcome of cognitive trajectories in older adults free of dementia: The Mayo Clinic Study of Aging

Objective Neuropsychiatric symptoms (NPS) are associated with the risk of incident mild cognitive impairment (MCI) and dementia. We examined associations between NPS and the outcomes of global and domain‐specific cognitive trajectories. Methods In this longitudinal study conducted in the setting of the population‐based Mayo Clinic Study of Aging, 5081 community‐dwelling, nondemented individuals aged ≥50 years (51% males) underwent NPS assessment using Neuropsychiatric Inventory Questionnaire (NPI‐Q), and Beck Depression and Anxiety Inventories (BDI‐II, BAI). Global and domain‐specific (memory, language, attention, and visuospatial skills) cognitive performance was assessed through neuropsychological testing every 15 months. Associations between baseline NPS and trajectories for individual yearly change in cognitive z‐scores were calculated using linear mixed‐effect models. Results Cognition declined regardless of NPS status over the median follow‐up of 4.5 years. Presence of NPS was associated with increased cognitive decline. Differences in annualized change in global cognition z‐scores for participants with NPS compared to without NPS ranged from −0.018 (95% CI −0.032, −0.004; p = 0.011) for irritability to −0.159 (−0.254, −0.065; p = 0.001) for hallucinations. Associations between NPS and annual decline in global cognition were significant for most NPI‐Q‐assessed NPS and clinical depression (BDI‐II≥13). Participants with NPI‐Q‐assessed depression, apathy, nighttime behavior, and clinical depression had greater decline in all domain‐specific z‐scores; presence of delusions and anxiety was associated with more pronounced decline in language, attention and visuospatial skills. Conclusion NPS were associated with a more accelerated cognitive decline. Clinical assessment and potential treatment of NPS is warranted even in a community setting as NPS may impact cognitive decline in nondemented individuals.