This may help doctors develop better treatments and prevent the disease from progressing.
Neurological specialists have known for a long time that people with Alzheimer’s disease experience pathological brain changes 10 years to 15 years before symptoms develop.
What they don’t understand is why symptoms do not occur as soon as the brain’s anatomy changes.
In the study, Stephen Rao, PhD, led a team of Cleveland Clinic researchers that divided 45 people into two groups. One group was at high genetic risk for developing Alzheimer’s disease. The other was at low-risk for developing Alzheimer’s. At the start of the study, neither group had signs of disease.
A functional magnetic resonance imaging (fMRI) was done on each of the participants’ brains over a five-year period. Participants were asked to perform memory tests during the MRI.
Functional MRI measures tiny changes that take place in an active part of the brain. The technology measures brain activity by detecting changes in blood flow.
The researchers found that in the high-risk group, brain activity during the memory task was higher at the outset of the study. Their brains were working harder to compensate for Alzheimer’s changes. However, brain activity decreased over time as the symptoms of Alzheimer’s disease began to emerge and the brain was no longer able to compensate.
In contrast, the low-risk group started out with lower brain activity that increased over time as a way to compensate for normal aging changes.
It was as if the healthy brains were building a reserve to compensate for normal memory loss.
“People at risk for Alzheimer’s show an increase in brain activity when they’re cognitively normal,” Dr. Rao says. “But when they start experiencing memory loss, we see a drop in their brain activation as time goes on.”
Dr. Rao says fMRI may be able to show us the way the brain copes with neurological damage at different stages of Alzheimer’s disease.
It also may be used to evaluate treatments for Alzheimer’s disease before a person has symptoms.
“We can use functional magnetic resonance imaging to look at the brain’s response to the memory system. We can then determine whether the intervention is working with that information ,” Dr. Rao says.
In addition, the study’s findings suggest that earlier treatment is beneficial to the patient, whether or not they exhibit symptoms. Earlier treatment could stop the disease in its tracks.
“If you institute a treatment during the pre-symptomatic phase, it is much more likely to be successful in delaying the progression,” Dr. Rao says.
The study gives scientists a gauge of the brain’s activity levels before symptoms occur, so they’re more likely to successfully develop treatments to slow disease progression and potentially prevent it from occurring.