David Salat, Ph.D.
(MGH)
Neuroimaging studies of aging and dementia
Prior work has demonstrated that the memory dysfunction of Alzheimer's
disease (AD) is accompanied by marked cortical pathology in medial
temporal lobe (MTL) gray matter. In particular, projection layers of the
entorhinal cortex exhibit profound pathological changes early in the
disease, with a resultant functional disconnection of the hippocampus
from the neocortex, which likely contributes to the classic memory
dysfunction that is present even in early AD. Although much is known about the cortical
pathology of AD, changes in white matter (WM) of pathways associated with
the MTL have rarely been studied. We used diffusion tensor imaging (DTI)
to examine regional patterns of WM tissue changes in normal aging and
in AD. Regional changes in WM integrity were greatest frontally in older adults compared to
younger adults, and in the MTL memory system with AD. Changes with AD
were related to neuroimaging indices of gray matter degeneration
including hippocampal volume and regional cortical thickness. WM
degeneration may result in a disconnection of cortical regions and contribute to cognitive dysfunction
with aging and age-associated degenerative disease.
|
