Alzheimer's, Dementia & Mental Health
Changes in Brain White Matter of Senior Citizens an
Early Sign of Alzheimer’s Disease
High-risk group of seniors showed decreased integrity
in white matter tracts that inter-connect gray matter regions involved
in memory function
 |
|
MRIs reveal white
matter tracts showing decreased integrity in normal seniors at
high risk for Alzheimer’s disease. The white matter tracts are
shown in green. Those tracts affected (shown in red) connect
gray matter structures involved in memory formation such as the
medial temporal and inferior frontal lobes. |
June 28, 2010 – Advances in various imaging
techniques appear to bringing scientists much closer to early detection
of Alzheimer’s disease. The latest detection method used a recently
developed form of MRI called diffusion tensor imaging (DTI) to study the
changes in white matter in the brains of senior citizens at risk for AD.
The research, led by Brian Gold, associate
professor of anatomy and neurobiology, University of Kentucky College of
Medicine, identified changes in the brains of normal seniors at high
risk for Alzheimer's disease that could prove important for early
detection of the disease.
The research focused on the brain’s white matter,
which forms the majority of deep parts of the brain and consists
primarily of myelinated nerve cell processes, or axons.
These myelinated axons serve to connect the brain’s
gray matter regions, which contain nerve cell bodies.
"The brain’s white matter can be thought of as a
set of telephone wires which enable communication between gray matter
'thinking regions'," Gold said.
Previous studies have demonstrated decline in both
gray and white matter tissue types in individuals with Alzheimer's. In
the present study, the authors sought to determine which of these
changes are present in normal seniors at high risk for Alzheimer's
disease, a likely target group for emerging interventions.
The high-risk group consisted of individuals whom
have both genetic and family risk factors for Alzheimer's disease but do
not yet show cognitive changes. The low-risk control group consisted of
individuals who had neither risk factor but were similar to the
high-risk group in terms of age, education level and cognitive
functioning.
The study used several magnetic resonance imaging
(MRI) techniques to assess the integrity of gray matter and white matter
brain tissue in the high and low risk groups. In particular, the
diffusion tensor imaging (DTI) was used to assess the integrity of the
brain’s white matter. This technique allows for assessment of the
microstructural integrity of axons and their surrounding myelin.
Results indicated that the two groups did not
differ in the tissue volumes of several gray matter regions known to
contribute to memory function.
However, the high-risk group of senior citizens
showed decreased integrity in white matter tracts that inter-connect
gray matter regions involved in memory function. Both the axonal and
myelin integrity of these white matter tracts were reduced.
These data suggest that changes in white matter
connections may be among the earliest brain changes in Alzheimer's
disease, which may prove important for early detection by non-invasive
imaging. In addition, the findings may have implications for the
development of new preventative treatment interventions in Alzheimer's
disease, which could attempt to protect axon and myelin integrity in
seniors at risk for this neurological disorder.
The findings were published in an article in the
journal Neuroimage. This research was supported by grants from
the National Institutes of Health and the National Science Foundation.
