April 14, 2011
Brain Shrinkage Could Predict Alzheimer’s
Parts of the brain affected by Alzheimer's disease could start shrinking up to a decade before the actual onset of dementia is diagnosed, according to a new US study on Wednesday.
Scientists said the findings, while still preliminary, could one day provide a way to identify by MRI which individuals are most likely to develop the disease, which has no cure.
In the new study, published in the journal Neurology Wednesday, researchers used MRI scans to measure areas of the brain in people with no memory problems or other signs of Alzheimer's, then followed them for years to see who developed the disease.
They followed two separate groups -- one group of 33 was tracked for 11 years and another group of 32 was tracked for eight years.
The team focused their measurements on areas known to be involved in Alzheimer's disease. They found that those with smaller brain size in the Alzheimer's-related areas of the brain were much more likely to develop the disease than those with larger measurements.
"This measure is potentially an important imaging marker of early changes in the brain associated with Alzheimer's disease that could help predict who might develop the dementia associated with this disease and possibly even how long it would be before dementia develops," said study author Bradford Dickerson, MD, of Harvard Medical School in Boston and a member of the American Academy of Neurology.
Over the course of the study, eight people in the first group and seven in the second developed AD.
When researchers looked at past brain scans of the participants, they found early signs of shrinkage in the ones who would develop the disease.
"Of the 11 people who had the lowest MRI measurements, 55 percent developed Alzheimer's, while none of the nine people with the highest measurements developed dementia," said the study.
20 percent of those with average brain measurements developed the disease.
"We also found that those who express this MRI marker of the Alzheimer's disease in the brain were three times more likely to develop dementia over the following 10 years than those with higher measurements," Dickerson said. "These are preliminary results that are not ready to be applied outside of research studies right now, but we are optimistic that this marker will be useful in the future."
Alzheimer's is the most common form of dementia and is estimated to affect five million Americans.
As the disease advances, symptoms include confusion, aggression, mood swings, language breakdown, memory loss, and general withdrawal of the sufferer as their senses decline. Gradually bodily functions are lost, ultimately leading to death. Life expectancy following diagnosis is about seven years, but very few cases have seen patients living as long as 14 years after diagnosis.
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