If you're genetically disposed to develop Alzheimer's, researchers at Washington University Medical School have some good news and some bad news for you.
The good news is, they've recently discovered that your brain starts functioning differently even before it begins producing the telltale deposits of amyloid plaque that lead to senility. The bad news? They still haven't figured out what to do with this information, so for now, your only benefit is an earlier warning that the disease is coming.
In a recent study, a group of researchers led by Dr. Yvette I. Sheline conducted MRI scans and spinal fluid tests on 100 people. Their average age was 62, and half of the participants carried a gene called APOE4, which is known to be a risk factor for late-onset Alzheimer's.
The researchers found that none of the research subjects had amyloid deposits in their brains or abnormal levels of amyloid protein in their spinal fluid. But they noticed that the brains of the APOE4 carriers had already begun to function differently.
"We looked at a group of structures in the brain that make up what's called the default mode network," Sheline explained in a press release. "In particular, we are interested in a part of the brain called the precuneus, which may be important in Alzheimer's disease and in pre-Alzheimer's because it is one of the first regions to develop amyloid deposits. Another factor is that when you look at all of the structural and functional connections in the brain, the most connected structure is the precuneus. It links many other key brain structures together."
In earlier studies, Sheline's team had compared the default mode networks of people with Alzheimer's and people with amyloid deposits to healthy people with no signs of brain plaque. In this most recent study, they determined that the default mode networks of people genetically-disposed toward Alzheimer's were already failing to make connections between different parts of the brain even though there were no signs of amyloid plaque.
Sheline and her team plan to follow up on the APOE4 carriers in the study to see how long it takes for their brains to start producing the plaque.
"The current belief is that from the time excess amyloid begins to collect in the brain, it takes about 10 years for a person to develop dementia," Sheline said. "But this new study would suggest we might be able to intervene even before amyloid plaques begin to form. That could give us an even longer time window to intervene once an effective treatment can be developed."