Neuropsychiatric, cognitive symptoms ‘independent manifestations’ of AD

Neuropsychiatric and cognitive symptoms were common across the Alzheimer’s disease continuum but evolved differently during the course of the disease, according to results of a single-center observational study published in Neurology.

“As neuropsychiatric symptoms are present in the majority of patients with AD dementia, [neuropsychiatric symptoms] are increasingly recognized as core clinical AD symptoms,” Willem S. Eikelboom, MSc, of the department of neurology at Erasmus University Medical Center in the Netherlands, and colleagues wrote. “Previous studies have associated the presence of [neuropsychiatric symptoms] with an increased risk [for] progression to dementia and with worse cognitive performance and a faster cognitive decline in AD dementia. These studies have emphasized the clinical relevance of [neuropsychiatric symptoms] in AD by highlighting its prognostic value.”

However, other studies showed no association between neuropsychiatric symptoms and cognitive functioning in AD dementia, which may have been due to the use of instruments that evaluate general cognitive functioning and overall neuropsychiatric symptom burden, according to the researchers. In the current study, they aimed to examine the prevalence and trajectories of neuropsychiatric symptoms and their association with cognitive functioning among individuals who were positive for amyloid-beta across the AD clinical spectrum. They included 1,542 individuals who visited the Alzheimer Center Amsterdam and were clinically diagnosed with subjective cognitive decline (n = 113), mild cognitive impairment (n = 321) or probable AD dementia (n = 1,090), and were positive for amyloid-beta.

Further, Eikelboom and colleagues assessed neuropsychiatric using the Neuropsychiatric Inventory (NPI), evaluating total scores and the presence of specific NPI domains. They used the Mini-Mental State Examination (MMSE) to examine global cognitive functioning and a standardized neuropsychological test battery to examine performance across five cognitive domains.

Results showed high prevalence of neuropsychiatric symptoms across all clinical AD stages. The researchers noted a uniform gradual decline in cognitive function; however, there was large intraindividual heterogeneity of neuropsychiatric symptoms over time across all AD groups.

Eikelboom and colleagues observed baseline associations between neuropsychiatric symptoms and cognition that were most significant for NPI total scores and MMSE. However, they observed no associations between baseline neuropsychiatric cognitive functioning over time in any clinical stage.

“These findings suggest that [neuropsychiatric symptoms] and cognitive symptoms are independent manifestations of AD that show a different evolution over the course of the disease,” the researchers wrote.