Brain Starts Shrinking Nearly a Decade Before Alzheimer's Appears

Regions of the brain affected by Alzheimer's disease (AD) may start shrinking up to 10 years before dementia is diagnosed, according to a new imaging research.

The study's findings were published in the April 13, 2011, issue of Neurology, the medical journal of the American Academy of Neurology. For the study, investigators utilized MRI scans to measure areas of the brain in people with no memory difficulties or other characteristics of Alzheimer's, then tracked them for years to see who developed the disorder. The researchers specifically focused their measurements on areas known to be involved in AD. Those with smaller brain size in the AD-related areas of the brain were much more apt 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 (Boston, MA, USA) and a member of the American Academy of Neurology (St. Paul, MN, USA).

The study involved two separate groups of people with no signs of AD. In the first group, 33 people were followed for an average of 11 years. During that time, eight of the participants developed AD dementia. In the second group, 32 people were followed for an average of seven years, and seven of them developed the disease.

The study participants were divided into three groups based on the MR brain scans: those with low, average, and high measurements in the Alzheimer's-related areas. Of the 11 people who had the lowest MRI measurements, 55% developed AD, while none of the nine people with the highest measurements developed dementia. Of those with average measurements, 20% 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," Dr. 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."

The study was conducted by investigators from Massachusetts General Hospital/Harvard Medical School and Rush University (Chicago, IL, USA).

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