Neuropsychological prediction of conversion to Alzheimer disease in patients with mild cognitive impairment.
BACKGROUND
The likelihood of conversion to Alzheimer disease (AD) in mild cognitive impairment (MCI) and the "optimal" early markers of conversion need to be established.


OBJECTIVE
To evaluate conversion rates to AD in subtypes of MCI and to identify neuropsychological measures most predictive of the time to conversion.


METHODS
Patients were followed up semiannually and controls annually. Subtypes of MCI were determined by using demographically adjusted regression norms on neuropsychological tests. Survival analysis was used to identify the most predictive neuropsychological measures.


METHODS
Memory disorders clinic.


METHODS
One hundred forty-eight patients reporting memory problems and 63 group-matched controls.


METHODS
A consensus diagnosis of probable AD.


RESULTS
At baseline, 108 patients met criteria for amnestic MCI: 87 had memory plus other cognitive domain deficits and 21 had pure memory deficits. The mean duration of follow-up for the 148 patients was 46.6 +/- 24.6 months. In 3 years, 32 (50.0%) of 64 amnestic-"plus" and 2 (10.0%) of 20 "pure" amnestic patients converted to AD (P = .001). In 148 patients, of 5 a priori predictors, the percent savings from immediate to delayed recall on the Selective Reminding Test and the Wechsler Adult Intelligence Scale-Revised Digit Symbol Test were the strongest predictors of time to conversion. From the entire neuropsychological test battery, a stepwise selection procedure retained 2 measures in the final model: total immediate recall on the Selective Reminding Test (odds ratio per 1-point decrease, 1.10; 95% confidence interval, 1.05-1.14; P < .0001) and Digit Symbol Test coding (odds ratio, 1.06; 95% confidence interval, 1.01-1.11; P = .01). The combined predictive accuracy of these 2 measures for conversion by 3 years was 86%.


CONCLUSIONS
Mild cognitively impaired patients with memory plus other cognitive domain deficits, rather than those with pure amnestic MCI, constituted the high-risk group. Deficits in verbal memory and psychomotor speed/executive function abilities strongly predicted conversion to AD.
Tabert
Matthias H
MH
Department of Psychiatry, Columbia University College of Physicians and Surgeons and the New York State Psychiatric Institute, 1051 Riverside Dr, Unit 126, New York, NY 10032, USA. mht35@columbia.edu
Manly
Jennifer J
JJ
Liu
Xinhua
X
Pelton
Gregory H
GH
Rosenblum
Sara
S
Jacobs
Marni
M
Zamora
Diana
D
Goodkind
Madeleine
M
Bell
Karen
K
Stern
Yaakov
Y
Devanand
D P
DP
D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis / Q000453:epidemiology*; D003072:Cognition Disorders / Q000145:classification / Q000175:diagnosis* / Q000453:epidemiology; D015897:Comorbidity; D018450:Disease Progression; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008569:Memory Disorders / Q000175:diagnosis / Q000453:epidemiology; D009483:Neuropsychological Tests / Q000706:statistics & numerical data*; D011237:Predictive Value of Tests; D011379:Prognosis; D012044:Regression Analysis; D012307:Risk Factors; D012720:Severity of Illness Index; D016019:Survival Analysis