Alterations in the functional activity of regions in the cortical autonomic network
(CAN) occur with aging. This study tested the hypothesis that the structural connectivity
and fractional anisotropy (FA) of gray matter regions in the CAN would be compromised
with aging. Diffusion tensor imaging (BrainVoyager) was used to perform tractography
and measure FA in the anterior and posterior insular cortex (IC), the subgenual anterior
cingulate cortex (sACC), and the posterior cingulate cortex (PCC) in 11 young (25±3 yr), 10 older hypertensive (HT; 58±6 yr), and 12 older normotensive participants (NT; 64±3 yr). In young, connections were observed between the anterior IC-sACC (left, 7/11;
right, 9/11), as well as between the posterior IC-PCC (left, 10/11; right, 8/11).
In HT, connections were observed between the anterior IC-sACC (left, 6/12; right 7/12),
as well as between the posterior IC-PCC (left, 11/12; right, 6/12). In NT, few connections
were observed between anterior IC-sACC (left, 1/10; right, 1/10), and more posterior
IC-PCC connectivity (left, 9/10; right, 6/10). The FA values were not different between
HT and NT and these values were grouped. Compared to young, the FA values were lower
in the older groups for each of the left anterior IC (0.29 vs. 0.26), the left posterior
IC (0.29 vs. 0.26), the right anterior IC (0.27 vs. 0.23), and the right posterior
IC (0.33 vs. 0.30) (all P<0.05). The FA of the sACC was not different between young, HT or NT whereas FA of
the PCC was higher in the older groups (0.30) compared to young (0.20; P<0.05). It was concluded that in this group, aging was associated with reduced white
matter connectivity between CAN regions that degrade anteriorly. The microstructural
alterations in the insula may contribute to autonomic dysregulation in aging.
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© 2010 Published by Elsevier Inc.