title: Predictors of Retest Effects in a Longitudinal Study of Cognitive Aging in a Diverse Community-Based Sample.
abstract: Better performance due to repeated testing can bias long-term trajectories of cognitive aging and correlates of change. We examined whether retest effects differ as a function of individual differences pertinent to cognitive aging: race/ethnicity, age, sex, language, years of education, literacy, and dementia risk factors including apolipoprotein E ε4 status, baseline cognitive performance, and cardiovascular risk. We used data from the Washington Heights-Inwood Columbia Aging Project, a community-based cohort of older adults (n=4073). We modeled cognitive change and retest effects in summary factors for general cognitive performance, memory, executive functioning, and language using multilevel models. Retest effects were parameterized in two ways, as improvement between the first and subsequent testings, and as the square root of the number of prior testings. We evaluated whether the retest effect differed by individual characteristics. The mean retest effect for general cognitive performance was 0.60 standard deviations (95% confidence interval [0.46, 0.74]), and was similar for memory, executive functioning, and language. Retest effects were greater for participants in the lowest quartile of cognitive performance (many of whom met criteria for dementia based on a study algorithm), consistent with regression to the mean. Retest did not differ by other characteristics. Retest effects are large in this community-based sample, but do not vary by demographic or dementia-related characteristics. Differential retest effects may not limit the generalizability of inferences across different groups in longitudinal research.
authors.affiliation: 1Departments of Epidemiology and Mental Health,Johns Hopkins Bloomberg School of Public Health,Baltimore,Maryland; and Center on Aging and Health,Johns Hopkins University,Baltimore,Maryland.
authors.forename: Alden L
authors.initials: AL
authors.lastname: Gross
authors.affiliation: 2Department of Radiology and Radiological Sciences,Center for Biomedical Imaging,Medical University of South Carolina,Charleston,South Carolina.
authors.forename: Andreana
authors.initials: A
authors.lastname: Benitez
authors.affiliation: 3RAND Corporation,Arlington, Virginia.
authors.forename: Regina
authors.initials: R
authors.lastname: Shih
authors.affiliation: 4Department of Psychiatry,University of California,San Diego,La Jolla,California.
authors.forename: Katherine J
authors.initials: KJ
authors.lastname: Bangen
authors.affiliation: 5Department of Epidemiology and Biostatistics,University of California San Francisco,San Francisco,California.
authors.forename: M Maria M
authors.initials: MM
authors.lastname: Glymour
authors.affiliation: 6Department of Neurology,Wake Forest Baptist Medical Center,Winston Salem,North Carolina.
authors.forename: Bonnie
authors.initials: B
authors.lastname: Sachs
authors.affiliation: 7North Florida/South Georgia Veterans Health System,Department of Veterans Affairs,Gainesville,Florida.
authors.forename: Shannon
authors.initials: S
authors.lastname: Sisco
authors.affiliation: 8Department of Psychiatry and Behavioral Sciences,University of Washington School of Medicine,Seattle,Washington.
authors.forename: Jeannine
authors.initials: J
authors.lastname: Skinner
authors.affiliation: 9Department of Psychiatry and Psychotherapie,University Hospital Hamburg-Eppendorf,Hamburg,Germany.
authors.forename: Brooke C
authors.initials: BC
authors.lastname: Schneider
authors.affiliation: 10Taub Institute for Research on Alzheimer's disease and the Aging Brain,Columbia University,New York,New York; Gertrude H. Sergievsky Center,Columbia University,New York,New York; and Department of Neurology,College of Physicians and Surgeons,Columbia University,New York,New York.
authors.forename: Jennifer J
authors.initials: JJ
authors.lastname: Manly
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D003071:Cognition / Q000502:physiology*; D056344:Executive Function; D005260:Female; D006801:Humans; D007802:Language; D007807:Language Tests; D008137:Longitudinal Studies; D008297:Male; D008568:Memory; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D012307:Risk Factors
keywords: Gerontology; Individual differences; Neuropsychological testing; Older adults; Practice effect; Retest effect