INTRODUCTION: Online assessments are scalable and cost-effective for detecting cognitive changes, especially in elderly cohorts with limited mobility and higher vulnerability to neurological conditions. However, determining the uptake, adherence, and usability of these assessments in older adults, who may have less experience with mobile devices is crucial. METHODS: 1,776 members (aged 77) of the MRC National Survey of Health and Development (NSHD) were invited to complete 13 online cognitive tasks. Adherence was measured through task compliance, while uptake (consent, attempt, completion) was linked to health and sociodemographic factors. Usability was evaluated through qualitative feedback. RESULTS: This study's consent (56.9%), attempt (80.5%), and completion (88.8%) rates are comparable to supervised NSHD sub-studies. Significant predictors of uptake included education, sex, handedness, cognitive scores, weight, smoking, alcohol consumption, and disease burden. DISCUSSION: With key recommendations followed, online cognitive assessments are feasible, with good adherence, and usability in older adults.

The funders of the study had no role in study design, data collection, analysis, interpretation, report writing, or in the decision to submit the article for publication. AH is owner/director of H2 Cognitive Designs Ltd and Future Cognition Ltd, which produce online assessment technology and provide online survey data collection for third parties. PH is founder and director of H2 Cognitive Designs LTD, which develops and markets online cognitive tasks.

MR, MP, AW are funded by the Medical Research Council (MC_UU_00019/1 and 3). VG is supported by the Medical Research Council, MR/W00710X/1. MDG is funded by Imperial College London. ZC is funded by Kings College London. Insight 46 is funded by grants from Alzheimer's Research UK (ARUK-PG2014-1946, ARUK- PG2017-1946), Alzheimer's Association (SG-666374-UK BIRTH COHORT), the Medical Research Council Dementias Platform UK (CSUB19166), The Wolfson Foundation (PR/ylr/18575), The Medical Research Council (MC_UU_10019/1, MC_UU_10019/3), and Brain Research Trust (UCC14191). JMS J.M.S. is supported by University College London Hospitals Biomedical Research Centre.

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The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

National Research Ethics Service Committee London (REC reference 14/LO/1173) gave ethical approval for this work

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