Practice effects persist over two decades of cognitive testing: Implications for longitudinal research
Elman, J. A.; Buchholz, E.; Chen, R.; Sanderson-Cimino, M.; Bell, T. R.; Whitsel, N.; Bangen, K. J.; Cronin-Golomb, A.; Dale, A. M.; Eyler, L. T.; Fennema-Notestine, C.; Gillespie, N. A.; Granholm, E. L.; Gustavson, D. E.; Hagler, D. J.; Hauger, R. L.; Jacobs, D. M.; Jak, A. J.; Logue, M. W.; Lyons, M. J.; McKenzie, R. E.; Neale, M. C.; Rissman, R. E.; Reynolds, C. A.; Toomey, R.; Wingfield, A.; Xian, H.; Tu, X. M.; Franz, C. E.; Kremen, W. S.; Panizzon, M. S.
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INTRODUCTIONRepeated cognitive testing can boost scores due to practice effects (PEs). 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. METHODMen (N=1,608) in the Vietnam Era Twin Study of Aging (VETSA) underwent neuropsychological assessment across 4 waves from mean age 56 to 74. We leveraged age-matched attrition-replacement (AR) participants to estimate PEs at each wave. We compared cognitive trajectories and prevalence of mild cognitive impairment (MCI) using unadjusted versus PE-adjusted scores. RESULTSAcross follow-ups, a range of 7-12 out of 30 measures demonstrated significant PEs, especially in episodic memory and visuospatial domains. Adjusting for PEs resulted in steeper cognitive decline with up to 29% higher MCI prevalence. DISCUSSIONPEs persist across multiple assessments and decades. The AR-participant method provides accurate sample-specific PE estimates that enable significantly earlier detection of MCI.
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