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MedRxiv preprint available at. https://doi.org/10.1101/2025.06.16.25329587
Elman et al. (2025)
ABSTRACT
Background: Repeated cognitive testing can boost scores due to practice effects (PEs), yet it remains unclear whether PEs persist across multiple follow-ups and long durations. We examined PEs across multiple assessments from midlife to old age in a nonclinical sample.
Method: Men (N=1,608) in the Vietnam Era Twin Study of Aging (VETSA) underwent
neuropsychological assessment comprising 30 measures across 4 waves (~6-year testing intervals) spanning up to 20 years. We leveraged age-matched replacement participants to estimate PEs at each wave. We compared cognitive trajectories and MCI prevalence using unadjusted versus PE-adjusted scores.
Results: Across follow-ups, a range of 7-12 tests (out of 30) demonstrated significant PEs, especially in episodic memory and visuospatial domains. Adjusting for PEs resulted in improved detection of cognitive decline and MCI, with up to 20% higher MCI prevalence.
Conclusion: PEs persist across multiple assessments and decades underscoring the
importance of accounting for PEs in longitudinal studies.
Keywords: practice effects; repeat testing; serial testing; longitudinal testing; mild cognitive impairment; cognitive change