Variability in annual Mini-Mental State Examination score in patients with probable Alzheimer disease: a clinical perspective of data from the Consortium to Establish a Registry for Alzheimer's Disease.
OBJECTIVE
To determine the variability in annual Mini-Mental State Examination scores of patients with Alzheimer disease enrolled in the Consortium to Establish a Registry for Alzheimer's Disease (CERAD).


METHODS
A total of 372 patients with probable Alzheimer disease with 1 or more years of follow-up.


METHODS
Twenty-one CERAD clinical sites throughout the United States.


RESULTS
An average annual decline of 3.4 points in CERAD patients returning for longitudinal reassessments was close to the SD of the measurement error of 2.8 points for the Mini-Mental State Examination. There was wide variability in individual rates of decline. Even with 4 years of follow-up, 15.8% of the patients had no clinically meaningful decline in Mini-Mental State Examination score (defined as a change in initial score >3, ie, 1 SD of measurement error). Validity of measurements of the rate of change in Mini-Mental State Examination scores improved with longer observation intervals and was reliable for most patients when observations were separated by 3 or more years.


CONCLUSIONS
Although the Mini-Mental State Examination is a useful screening instrument to assess level of cognitive function, it has limited value in measuring the progression of Alzheimer disease in individual patients for periods less than 3 years because of a large measurement error and substantial variation in change in annual score.
Clark
C M
CM
Department of Neurology, Alzheimer's Disease Center, University of Pennsylvania, Philadelphia 19104, USA. ClarkC@mail.med.upenn.edu
Sheppard
L
L
Fillenbaum
G G
GG
Galasko
D
D
Morris
J C
JC
Koss
E
E
Mohs
R
R
Heyman
A
A
D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis*; D003072:Cognition Disorders / Q000175:diagnosis*; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D012042:Registries; D012720:Severity of Illness Index