Sc. Johnson et al., The relationship between fMRI activation and cerebral atrophy: Comparison of normal aging and Alzheimer disease, NEUROIMAGE, 11(3), 2000, pp. 179-187
Functional MRI has recently been used to examine activation associated with
aging and dementia, yet little is known regarding the effect of cerebral a
trophy on fMRI signal. The purpose of this study was to examine the relatio
nship between measures of global and regionally specific atrophy and fMRI a
ctivation in normal aging and in Alzheimer disease (AD). Two groups of subj
ects were studied with echoplanar imaging and quantitative structural volum
etry: healthy controls spanning a broad age and atrophy range (n = 16) and
patients with mild AD (n = 8), Results from a semantic task previously foun
d to activate left inferior frontal (LIFG) and left, superior temporal (LST
G) gyri were analyzed. The correlations between clusters of activation in t
he LIFG and LSTG; and measures of local atrophy in the LIFG and LSTG; regio
ns were evaluated. For control subjects, there was no significant correlati
on between activation and regional or total brain atrophy (for LIFG r = -0.
03, NS; for LSTG r = 0.20, NS). In contrast, for AD patients, there was a s
ignificant positive correlation between atrophy and activation in LIFG (r =
0.70, P = 0.05) but not LSTG (r = 0.00, NS). These results suggest that ac
tivation of language regions and atrophy within those regions may be indepe
ndent among healthy adults spanning a broad age and atrophy range. However,
in AD, a relationship exists in the LIFG that may reflect compensatory rec
ruitment of cortical units or disease-specific changes in the hemodynamic r
esponse. (C) 2000 Academic Press.