Magnetic resonance imaging (MRI), a
type of scan already in wide use, may prove to be an effective way to identify
Alzheimer's disease in its early stages, according to results of a new study.
Eventually, MRI may aid in the treatment of Alzheimer's, since it helps
identify which people are at greatest risk of developing the disorder,
researchers report. It may also be used to monitor the effectiveness of drugs
used to treat Alzheimer's.
"If we can be really specific in the way we measure what is happening in the
brain prior to the development of Alzheimer's disease, we are likely to be very
accurate in identifying the disease before it's full-blown," Dr. Marilyn S.
Albert, of Massachusetts General Hospital in Boston, told Reuters Health in an
interview.
According to previous research, changes in a region of the brain called the
hippocampus occur before symptoms begin, but Albert said that she and her
colleagues were able to look more closely than ever at several parts of the
brain believed to be involved with the disease.
The study of elderly men and women included 24 healthy people, 79 with mild
memory problems, and 16 with mild Alzheimer's disease. At the start of the
study, everyone underwent MRI, which measured the volume of several brain
regions. By the end of the 3-year study, 19 of the 79 participants with mild
memory problems had worsened and were judged to have probable Alzheimer's.
At the end of the study, researchers analyzed the MRIs conducted at the
start of the study to see whether they could detect any differences between the
groups. Most of the time, the investigators were able to correctly classify a
person based on the MRI readings of three sections of his or her brain: the
entorhinal cortex and the banks of the superior temporal sulcus, which are both
involved in memory, and the anterior cingulate, which is involved in functions
like organizing, planning and switching from task to task.
The scans were 100% accurate in differentiating between healthy people and
those with mild Alzheimer's. The accuracy was 93% for distinguishing between
normal subjects and those that appeared to develop Alzheimer's during the study,
and 85% for distinguishing between normal subjects and those with mild memory
problems at the start of the study.
MRI was least useful in determining which participants with mild memory
problems would "convert" to Alzheimer's by the end of the study. The accuracy
for distinguishing between these groups was 75%. But, the researchers speculate
that this rate might improve if other measures are used along with MRI.
In her comments to Reuters Health, Albert noted that identifying patients in
the early stages of Alzheimer's may be important for the treatment of the
disease. "We believe that in the next decade or so, there are likely to be
effective treatments for the disease," Albert said. Most likely, though, they
will have side effects and will be expensive, so determining which patients are
"really on the pathway to developing Alzheimer's disease" will be essential, she
added. Albert also said that MRI might be used to measure the effectiveness of
therapy.
