| |
Abstract:
Abstract: Aim: Neurofunctional investigation of age-related
change in executive cognition is preliminary. We therefore tested
in vivo the hypothesis that variations in the neurometabolic
integrity of projections linking prefrontal and subcortical
structures may mediate these processes in old age. Methods: Twenty
healthy elderly volunteers (11 females, mean 72 years) underwent
over 4 weeks: neuropsychiatric assessment, neuropsychological
testing, combined whole brain T1-weighted/FLAIR MRI and topical
proton magnetic resonance spectroscopy (1H-MRS) in the left frontal
white matter and occipito-parietal gray matter. Percentage
fractions of CSF and hyperintense signal (HIS) were calculated for
each MRS region, as was anterior horn and mid-ventricular VBR.
Results: Principal components analysis produced a 3 factor
neuropsychological solution, the first (PC1) representing complex
executive-attentional ability (32% of variance). As expected, age,
frontal HIS%, and VBR-mid were each negatively correlated with PC1,
while NAA/Cr was positively correlated (r= 0.54, p < 0.02);
furthermore only frontal NAA/Cr significantly predicted PC1
(R-Square change = 0.167, p < 0.02) after first entering the
other predictors into a linear regression model. Discussion: We
found using 1H-MRS in the healthy elderly that individual
differences in subcorticofrontal axonal density or age-related
neurometabolic changes in the frontal white matter tracts are
functionally implicated in executive and attentional cognition,
independent of other known neurological predictors.
|
