The measurement of cognition in large-scale cross-national surveys: Lessons from the Health and Retirement International Network of Studies and the Harmonized Cognitive Assessment Protocol

Objectives Global dementia prevalence is expected to triple by 2050 with the majority of cases occuring in low- and middle-income countries (LMICs), prompting the need for robust cognitive measurement tools in global aging research. The Health and Retirement Study (HRS) and its international counterparts have pioneered cross-national cognitive assessments, most recently through the Harmonized Cognitive Assessment Protocol (HCAP). Methods Based on a series of discussions with key stakeholders and a review of the current literature, we report on key lessons from the HRS International Network of Surveys (HRS-INS) and HCAP in developing cross-nationally comparable cognitive testing protocols suitable for longitudinal research. Results These lessons emphasize the importance of ensuring tests are feasible across both high-income countries and LMICs, maintaining consistency within studies and over time, and designing comprehensive cognitive batteries for improved measurement precision of general and domain-specific phenotypes. We highlight challenges of administering cognitive tests across different cultural, educational, and linguistic contexts, which necessitate ongoing adaptation and pilot testing. Discussion By summarizing these experiences, this paper informs future efforts in enhancing the comparability and validity of cognitive assessments for cross-national aging studies, providing insights into optimizing survey design for the accurate measurement of cognitive functioning, cognitive decline, mild cognitive impairment, and dementia. Insights also enable data users to identify the limitations of existing data, thus facilitating more informed decision-making in analytic projects.