Factors associated with non-participation in the Healthy Cognitive Ageing Project

Alzheimers Dement. 2025 Apr;21(4):e70169. doi: 10.1002/alz.70169.

ABSTRACT

BACKGROUND: Understanding cognitive decline trajectories is crucial for dementia prevention, as many cases go undetected. Identifying participation biases in such studies is essential for data validity.

METHODS: We examined non-participation correlates in the Healthy Cognitive Ageing Project (HCAP), a sub-study of the English Longitudinal Study of Ageing (ELSA). We compared sociodemographic and health characteristics of invited, interviewed, and non-interviewed individuals, and assessed the impact of sample weights.

RESULTS: Of 1778 ELSA members invited in 2018, 1273 (72%) participated. Participants were similar to the invited sample in sociodemographics but were younger, had fewer daily living difficulties, and had better cognition. Non-participation was linked to difficulties in daily living (odds ratio 1.78), dementia (1.55), and psychiatric conditions (1.34). Weighted analyses highlighted differences in disability and cognition.

DISCUSSION: Non-participation in cognitive studies is not random, lowering response and retention rates, and requiring adjustments to data analysis beyond the use of weights.

HIGHLIGHTS: We compared the sociodemographics of invited, interviewed, and non-interviewed individuals. We used sample weights to assess differences in participants’ characteristics. We found non-participation linked to daily living difficulties, dementia, and psychiatric conditions.

PMID:40289680 | DOI:10.1002/alz.70169