Differences in Cognitive Aging Assessments Associated With Retest Effects

Area of Science:

• Gerontology
• Cognitive Neuroscience
• Clinical Trials

Background:

• Retest effects can inflate cognitive test performance, complicating the assessment of cognitive change over time.
• The influence of retest effects on estimated intervention effects in randomized clinical trials is not well understood.

Purpose of the Study:

• To quantify the magnitude and heterogeneity of retest differences in longitudinal cognitive testing.
• To examine whether accounting for retesting alters estimated treatment effects in the Aging and Cognitive Health Evaluation in Elders (ACHIEVE) trial.

Main Methods:

• Secondary analysis of the ACHIEVE phase 3 randomized clinical trial.
• Linear mixed-effects models were used to estimate retest differences, adjusting for covariates.
• Primary outcome was a global cognitive factor score; secondary outcomes included domain-specific scores.

Main Results:

• Significant retest differences were observed for global cognition, executive function, and memory, partially offsetting age-related decline.
• Retest differences did not vary meaningfully by hearing loss severity, intervention, or recruitment source.
• Adjusting for retest differences altered cognitive trajectories but did not significantly change intervention outcomes.

Conclusions:

• Retest differences are substantial in longitudinal cognitive assessments of older adults.
• Accounting for retest effects is recommended for improved interpretation of cognitive studies and intervention effects.
• Despite significant retest effects, hearing intervention outcomes in the ACHIEVE trial remained largely unchanged.