Calibration and validation of an innovative approach for estimating general cognitive performance.
OBJECTIVE
To evaluate a new approach for creating a composite measure of cognitive function, we calibrated a measure of general cognitive performance from existing neuropsychological batteries.


METHODS
We applied our approach in an epidemiological study and scaled the composite to a nationally representative sample of older adults. Criterion validity was evaluated against standard clinical diagnoses. Convergent validity was evaluated against the Mini-Mental State Examination (MMSE).


RESULTS
The general cognitive performance factor was scaled to have a mean of 50 and standard deviation of 10 in a nationally representative sample of older adults. A cutoff point of approximately 45, corresponding to an MMSE of 23/24, optimally discriminated participants with and without dementia (sensitivity = 0.94, specificity = 0.90, area under the curve = 0.97). The general cognitive performance factor was internally consistent (Cronbach's α = 0.91) and provided reliable measures of functional ability across a wide range of cognitive functioning. It demonstrated minimal floor and ceiling effects, which is an improvement over most individual cognitive tests.


CONCLUSIONS
The cognitive composite is a highly reliable measure, with minimal floor and ceiling effects. We calibrated it using a nationally representative sample of adults over the age of 70 in the USA and established diagnostically relevant cutoff points. Our methods can be used to harmonize neuropsychological test results across diverse settings and studies.
Aging Brain Center, Institute for Aging Research, Hebrew Senior Life, Harvard Medical School, Boston, Mass., USA.
Alden L
AL
Gross
Richard N
RN
Jones
Tamara G
TG
Fong
Douglas
D
Tommet
Sharon K
SK
Inouye
D000368:Aged; D000369:Aged, 80 and over; D002138:Calibration; D003071:Cognition; D003072:Cognition Disorders / Q000175:diagnosis; D003704:Dementia / Q000175:diagnosis; D005260:Female; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests