Assessing the construct validity of cross-national harmonized cognitive assessments using age.

Harmonized cognitive measures are key to cross-national comparisons of dementia risk. However, validating such measures cross-nationally is challenging due to differences in cognitive measures and a lack of a reference standard. Age, a characteristic strongly associated with cognition and widely measured, can serve as a benchmark for evaluating how well harmonized cognitive measures are broadly compatible with a common construct. We used cross-nationally harmonized measures from three studies in the US and five studies in England, Chile, Mexico, India, and South Africa ( = 27,317). Study-specific estimates of the association between general cognitive scores and age ranged from -0.040 to -0.075 SD units/year of age. The coefficient of variation was 24.1%, indicating moderate relative variability. Results support the hypothesis that cross-nationally harmonized scores, derived from partially overlapping test batteries, measure a broadly similar construct across countries. Future studies should further evaluate criterion, construct, and content validity of cognitive testing in cross-national populations.