[Abstract Title]. - Society for Neuroscience

Title: Frontal lobe activation changes during the digit symbol substitution test in Mild Cognitive
Impairment
Authors: *M. A. TRIVEDI, C. M. MURPHY, R. C. SHAH, J. D. E. GABRIELI, S.
WHITFIELD-GABRIELI, G. T. STEBBINS;
Neurolog Sci., Rush Univ. Med. Cntr, Chicago, IL
Abstract: The digit symbol substitution test (DSST) is a complex attention test. Previous studies
suggest that the DSST is also sensitive to the cognitive changes that occur during the
pathogenesis of Alzheimer‟s disease (AD). In the present study, we used a modified version of
the DSST to evaluate fMRI activation changes during DSST performance in individuals with
amnestic mild cognitive impairment (AMCI), a risk factor for AD. The two groups included in
this study were an ONC group (n = 15) and an AMCI group (n = 6). fMRI data processing was
conducted using the standard SPM2 routines. To examine fMRI activation changes associated
with DSST performance we created a contrast of “hits > misses”, that would allow us to
determine brain regions in which the AMCI group displayed increased or decreased brain
activation relative to the ONC group. Whole brain analysis failed to reveal any significant group
differences after FDR correction for multiple comparisons. However, follow-up region of
interest (ROI) analyses restricted to frontal cortex revealed that the AMCI group displayed
significantly greater activation than the ONC group bilaterally in the inferior frontal cortex and
in the left superior frontal cortex (p = 0.001). In contrast, there were no brain regions in which
the ONC group displayed significantly greater activation than the AMCI group. These
preliminary results might suggest that individuals with AMCI display greater activation in frontal
lobe regions important for complex attentional processes, possibly due to pathophysiological
changes associated with AD. A larger group of subjects will help to confirm these findings.
Disclosures: M.A. Trivedi , P01 AG09466, B. Research Grant (principal investigator,
collaborator or consultant and pending grants as well as grants already received); C.M. Murphy,
None; R.C. Shah, None; J.D.E. Gabrieli, None; S. Whitfield-Gabrieli, None; G.T. Stebbins,
None.
Poster
246. Alzheimer's Imaging and Biomarkers II
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 246.14/R2
Abstract: Withdrawn