Brain damage starts decade earlier in Alzheimer’s patients

By Dr. Ananya Mandal, MDApr 15 2011

A new study published in the journal Neurology has shown that the brains of people diagnosed with Alzheimer's disease start shrinking up to a decade before symptoms appear. Researchers from Rush University Medical Center in Chicago and Massachusetts General Hospital in Boston did brain imaging tests on older adults with no signs of memory loss.

Of the 33 people in the Mass General group, eight developed Alzheimer's over the course of 11 years. In the Rush group, seven of 32 people followed for an average of seven years developed the disease. About 55 percent of those whose brains were in the upper third of atrophy developed Alzheimer's, while none of those whose brains in the bottom third (little or no atrophy) developed Alzheimer's. Among those with moderate amounts of atrophy, about 20 percent developed the disease.

“We could differentiate those who would decline from those who would remain healthy,” said senior study author Leyla deToledo-Morrell, director of the graduate program in neuroscience at Rush University Medical Center. Based on the atrophy measurements, “we could even determine how quickly they were going to develop Alzheimer's disease,” she added.

Dr. Jeffrey Burns said that it has been known that Alzheimer's is an insidious disease, and that changes in the brain begin long before the first symptoms become evident. “This suggests, along with other studies, that Alzheimer's pathology is likely present years, if not decades, before the emergence of symptoms,” Burns said. Dr. Steven DeKosky said that the biochemical changes in the brain that are only partially understood cause degeneration of brain cells. Over time, the cells begin to die off, leading to structural changes in the brain tissue, or atrophy.

“The amount of atrophy was much, much, much less than in a person with Alzheimer's disease,” deToledo-Morrell said. “But because each one who developed Alzheimer's disease showed it, the results are extremely significant,” she added. “If we can identify people at risk of the disease, they would be at much greater benefit from receiving treatment, rather than people who have already developed Alzheimer's, who already have a certain amount of cell death and you can't really rescue those cells,” she said. Though the number of participants in the study was small and the findings need to be repeated in larger populations, it is “remarkable they saw changes this clear with this small number of cases,” DeKosky said.