Background: Understanding regional differences in cognitive performance is important for interpretation of data from large multinational clinical trials.
Methods: Data from Durham and Cabarrus Counties in North Carolina, USA and Tomsk, Russia (n = 2972) were evaluated. The Montreal Cognitive Assessment (MoCA), Trail Making Test Part B (Trails B), Consortium to Establish a Registry for Alzheimer's Disease Word List Memory Test (WLM) delayed recall, and self-report Alzheimer's Disease Cooperative Studies Mail-In Cognitive Function Screening Instrument (MCFSI) were administered at each site. Multilevel modeling measured the variance explained by site and predictors of cognitive performance.
Results: Site differences accounted for 11% of the variation in the MoCA, 1.6% in Trails B, 1.7% in WLM, and 0.8% in MCFSI scores. Prior memory testing was significantly associated with WLM. Diabetes and stroke were significantly associated with Trails B and MCFSI.
Conclusions: Sources of variation include cultural differences, health conditions, and exposure to test stimuli. Findings highlight the importance of local norms to interpret test performance.
Keywords: Alzheimer's disease; Cross-cultural comparison; Neuropsychological tests; Primary prevention delay of onset of MCI due to Alzheimer's disease.
Copyright © 2014 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.