Dysexecutive functioning in mild cognitive impairment: derailment in temporal gradients.
Libon et al. (2010) provided evidence for three statistically determined clusters of patients with mild cognitive impairment (MCI): amnesic (aMCI), dysexecutive (dMCI), and mixed (mxMCI). The current study further examined dysexecutive impairment in MCI using the framework of Fuster's (1997) derailed temporal gradients, that is, declining performance on executive tests over time or test epoch. Temporal gradients were operationally defined by calculating the slope of aggregate letter fluency output across 15-s epochs and accuracy indices for initial, middle, and latter triads from the Wechsler Memory Scale-Mental Control subtest (Boston Revision). For letter fluency, slope was steeper for dMCI compared to aMCI and NC groups. Between-group Mental Control analyses for triad 1 revealed worse dMCI performance than NC participants. On triad 2, dMCI scored lower than aMCI and NCs; on triad 3, mxMCI performed worse versus NCs. Within-group Mental Control analyses yielded equal performance across all triads for aMCI and NC participants. mxMCI scored lower on triad 1 compared to triads 2 and 3. dMCI participants also performed worse on triad 1 compared to triads 2 and 3, but scored higher on triad 3 versus triad 2. These data suggest impaired temporal gradients may provide a useful heuristic for understanding dysexecutive impairment in MCI.
Department of Neurology, Drexel University, College of Medicine, 245 North 15th Street, Philadelphia, PA 19102, USA.
Joel
J
Eppig
Denene
D
Wambach
Christine
C
Nieves
Catherine C
CC
Price
Melissa
M
Lamar
Lisa
L
Delano-Wood
Tania
T
Giovannetti
Brianne M
BM
Bettcher
Dana L
DL
Penney
Rod
R
Swenson
Carol
C
Lippa
Anahid
A
Kabasakalian
Mark W
MW
Bondi
David J
DJ
Libon
D000368:Aged; D000369:Aged, 80 and over; D000647:Amnesia / Q000503:physiopathology; D000704:Analysis of Variance; D016000:Cluster Analysis; D003072:Cognition Disorders / Q000145:classification / Q000503:physiopathology*; D056344:Executive Function / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D012189:Retrospective Studies; D014706:Verbal Learning