A clustering approach based on neuropsychological testing to detect early signs of probable MCI among community-dwelling older adults

Introduction: Mild Cognitive Impairment (MCI) is defined as a decline in one or more cognitive domains worse than expected for age and encompasses several subtypes depending on the cognitive(s) function(s) impaired. Older adults presenting amnestic MCI combined with one or several other impaired domains are the highest at risk of dementia. Yet, no consensual screening method for MCI in community-dwelling older adults has been established. The aim of this study was to identify cognitive aging profiles using multivariate analysis based on three neuropsychological assessments and to characterize profiles consistent with different probable MCI subtypes. Methods: A total of 161 community-dwelling older adults from the 13EVAL cluster-randomized controlled trial performed the Montreal Cognitive Assessment including the Memory Index Score, the Trail Making Test and the Victoria Stroop Test. Hierarchical clustering on principal components was conducted based on four cognitive domains (global cognition, memory, inhibition and cognitive flexibility) and age. Inter-groups comparisons were performed using one-way ANOVA. Individual performances were compared to normative standard for each assessment to characterize each group. Results: Three clusters were identified that differed significantly in age (F2,158=78.56, p<.001, 2p=.50), global cognition (F2,158=96.07, p<.001, 2p=.55), memory (F2,158=81.48, p<.001, 2p=.51), cognitive flexibility (F2,158=52.25, p<.001, 2p=.40) and inhibition (F2,158=12.14, p<.001, 2p=.13). Inter-groups comparisons and comparisons to normative values led to the characterization of Cluster 1 as normal cognition, Cluster 2 as probable executive MCI and Cluster 3 as probable amnestic and executive MCI. Conclusions: Individuals with cognitive profiles consistent with probable executive MCI were identified using simple assessments of global cognition, memory and executive functions in a community-dwelling older population. As participants were not clinically diagnosed, further prospective studies are needed to determine the screening performance of this approach.