Calibrating longitudinal cognition in Alzheimer's disease across diverse test batteries and datasets.
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.
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Md., USA.
Alden L
AL
Gross
Richard
R
Sherva
Shubhabrata
S
Mukherjee
Stephen
S
Newhouse
John S K
JS
Kauwe
Leanne M
LM
Munsie
Leo B
LB
Waterston
David A
DA
Bennett
Richard N
RN
Jones
Robert C
RC
Green
Paul K
PK
Crane
D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000523:psychology*; D003071:Cognition; D005163:Factor Analysis, Statistical; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000592:standards*; D015203:Reproducibility of Results