Calibrating Longitudinal Cognition in Alzheimer's Disease Across Diverse Test Batteries and Datasets

Abstract

Background: We sought to identify optimal approaches by calibrating longitudinal cognitive performance across studies with different neuropsychological batteries. Methods: We examined four approaches to calibrate cognitive performance in nine longitudinal studies of Alzheimer's disease (AD) (n = 10,875): (1) common test, (2) standardize and average available tests, (3) confirmatory factor analysis (CFA) with continuous indicators, and (4) CFA with categorical indicators. To compare precision, we determined the minimum sample sizes needed to detect 25% cognitive decline with 80% power. To compare criterion validity, we correlated cognitive change from each approach with 6-year changes in average cortical thickness and hippocampal volume using available MRI data from the AD Neuroimaging Initiative. Results: CFA with categorical indicators required the smallest sample size to detect 25% cognitive decline with 80% power (n = 232) compared to common test (n = 277), standardize-and-average (n = 291), and CFA with continuous indicators (n = 315) approaches. Associations with changes in biomarkers changes were the strongest for CFA with categorical indicators. Conclusions: CFA with categorical indicators demonstrated greater power to detect change and superior criterion validity compared to other approaches. It has wide applicability to directly compare cognitive performance across studies, making it a good way to obtain operational phenotypes for genetic analyses of cognitive decline among people with AD. i 2014 S. Karger AG, Basel

Application of Latent Variable Methods to the Study of Cognitive Decline When Tests Change over Time

“…The factor analysis approach we used is extendable to other studies in which measures of a construct differ across time; in fact, time is not the only dimension for which the approach could be used. Factor analysis has been successfully applied to harmonize cognitive performance,(5,39–40) physical functioning,(41) and depressive symptoms (42) across datasets .…”

“…Although categorization may coarsen the data, it diminishes the influence of truncation and outliers. (5) A final limitation is that temporal harmonization provided by factor analysis relies on common tests across time; the approach is not applicable in settings without anchor tests or items unless further assumptions are made.…”

“…This approach also has advantages of placing tests on a common scale (0 to 9) and accommodates skewed test indicators. (5) Common in cognitive aging research,(21–25) these transformations were based on empirical distributions in the data. In a sensitivity analysis, we derived factors using raw continuously distributed scores and compared results with those for the categorized scores.…”

The short‐term and long‐term relationship between delirium and cognitive trajectory in older surgical patients

“…26 The GCP, which is sensitive to change with minimal floor and ceiling effects, 26,27 has been applied in prior studies. 27,29–31 …”

Predictors of Retest Effects in a Longitudinal Study of Cognitive Aging in a Diverse Community-Based Sample

“…Details are provided elsewhere (Gross et al, 2014a, 2014b). Briefly, we calibrated the factors using a nationally representative sample of adults aged 70 and older from the Aging, Demographics, and Memory Study (ADAMS), a sub-study of the Health and Retirement Study (Juster & Suzman, 1995; Langa et al, 2005).…”