Identifying mild cognitive impairment at baseline in the Ginkgo Evaluation of Memory (GEM) study.
OBJECTIVE
To identify, characterize and compare the frequency of mild cognitive impairment (MCI) subtypes at baseline in a large, late-life cohort (n = 3063) recruited into a dementia prevention trial.


METHODS
A retrospective, data-algorithmic approach was used to classify participants as cognitively normal or MCI with corresponding subtype (e.g. amnestic vs. non-amnestic, single domain vs. multiple domain) based on a comprehensive battery of neuropsychological test scores, with and without Clinical Dementia Rating (CDR) global score included in the algorithm.


RESULTS
Overall, 15.7% of cases (n = 480) were classified as MCI. Amnestic MCI was characterized as unilateral memory impairment (i.e. only verbal or only visual memory impaired) or bilateral memory impairment (i.e. both verbal and visual memory impaired). All forms of amnestic MCI were almost twice as frequent as non-amnestic MCI (10.0% vs. 5.7%). Removing the CDR = 0.5 ('questionable dementia') criterion resulted in a near doubling of the overall MCI frequency to 28.1%.


CONCLUSIONS
Combining CDR and cognitive test data to classify participants as MCI resulted in overall MCI and amnestic MCI frequencies consistent with other large community-based studies, most of which relied on the 'gold standard' of individual case review and diagnostic consensus. The present data-driven approach may prove to be an effective alternative for use in future large-scale dementia prevention trials.
Snitz
Beth E
BE
Department of Neurology, University of Pittsburgh. snitzbe@upmc.edu
Saxton
Judith
J
Lopez
Oscar L
OL
Ives
Diane G
DG
Dunn
Leslie O
LO
Rapp
Stephen R
SR
Carlson
Michelle C
MC
Fitzpatrick
Annette L
AL
Dekosky
Steven T
ST
D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D003072:Cognition Disorders / Q000145:classification* / Q000175:diagnosis* / Q000453:epidemiology / Q000517:prevention & control; D015331:Cohort Studies; D006801:Humans; D007406:Interview, Psychological; D009483:Neuropsychological Tests; D012189:Retrospective Studies; D014481:United States / Q000453:epidemiology