World-wide variations in tests of cognition and activities of daily living in participants of six international randomized controlled trials

Background: Better understanding of worldwide variation in simple tests of cognition and global function in older adults would aid the delivery and interpretation of multi-national studies of the prevention of dementia and functional decline. Method: In six RCTs that measured cognition with the mini-mental state examination (MMSE), Montreal cognitive assessment (MoCA), and activities of daily living (ADL) with the Standardised Assessment of Everyday Global Activities (SAGEA), we estimated average scores by global region with multilevel mixed-effects models. We estimated the proportion of participants with cognitive or functional impairment with previously defined thresholds (MMSE≤24 or MoCA≤25, SAGEA≥7), and with a country-standardised z-score threshold of cognitive or functional score of ≤-1. Results: In 91,396 participants (mean age 66.6 years [SD 7.8], 31% females) from seven world regions, all global regions differed significantly in estimated cognitive function (z-score differences 0.11–0.45, p