Brain Scans Support Cognitive Reserve Theory for Preventin...

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April 13, 2009

April 13, 2009

Education may provide mental reserves that help to keep the brain agile into old age. Those are the findings of a new study from researchers at Washington University School of Medicine in St. Louis.

Other studies have shown similar correlations between years of education and risk of Alzheimer's disease. But the current study suggested that even those individuals whose brains appeared "scarred" by Alzheimer's could still be cognitively normal, especially if they had received more years of formal education.

The researchers found that seniors with the most years of formal education scored higher on tests of memory, learning and thinking compared to those who spent the least time in school. In fact, many of the highly educated individuals who did well on the memory tests were shown by imaging tests to have the same kind of damage seen in the brains of those with Alzheimer's disease. The findings were published in the Archives of Neurology, one of the medical journals from the American Medical Association.

The findings support the cognitive reserve theory, which refers to the brain's ability to nurture healthy brain cells and connections between them. As people age, diseases like Alzheimer's ravage the brain with the buildup of toxic proteins that form plaques and tangles. But according to the cognitive reserve theory, if enough healthy brain cells and brain cell connections remain, people can escape symptoms like memory loss and disordered thinking that are typical of Alzheimer's disease.

Education is thought to boost cognitive reserve. Intellectual challenges to the brain early in life from schoolwork are thought to build brain cells and enrich the connections between them, effects that may be maintained into later years.

Earlier studies of normal aging have found that higher levels of educational attainment were associated with less cognitive and functional decline. And having few years of formal education has also been linked to an increased risk of Alzheimer's. A study last year from Finland found, for example, that teenage dropouts were at higher risk of developing Alzheimer's years later than those who got their diplomas and continued with further study. [See the article, "A Warning for High-School Dropouts"]

Intellectually stimulating careers and hobbies, like learning a new language, playing a musical instrument or doing crossword puzzles or word games, build extra brainpower. Healthier brain cells and connections may help compensate for the rise in Alzhiemer's-like brain changes that accompany normal aging.

What the Study Showed

In the study, Catherine M. Roe, Ph.D., and colleagues at Washington University studied nearly 200 seniors (mean age 67) over a five-year period. Thirty-seven had a diagnosis of Alzheimer's disease, while 161 had no signs of dementia.

The researchers injected the study participants with a radioactive substance called Pittsburgh compound B, and then scanned their brains using an advanced imaging technique called positron emission tomography, or PET. The imaging agent, developed by scientists at the University of Pittsburgh Medical Center, indicates brain areas damaged by Alzheimer's by attaching to deposits of beta-amyloid, the toxic protein that builds up and forms plaques in the brains of those with the disease.

In the study, certain individuals' brains absorbed the most Pittsburgh compound B, an indication that their brains were riddled with the greatest numbers of beta-amyloid plaques. But the more years of education that they had, the less likely they were to perform poorly on memory and thinking tests. In other words, their education seemed to protect them against the memory loss and other symptoms of Alzheimer's disease.

"The results support the hypothesis that cognitive reserve influences the association between Alzheimer's disease pathological burden and cognition," the authors wrote.

It is thought that symptoms of Alzheimer's would eventually emerge as beta-amyloid plaques continue to accumulate, even in the most highly educated people. But for many seniors, living into their 70s and 80s sharp as a tack, education and mental stimulation is thought to strengthen cognitive reserve and possibly protect against Alzheimer's. And many people will die of other causes before the effects of Alzheimer's become evident.

Further testing of individuals living into old age will allow researchers to continue to test this theory. In the meantime, stay in school, turn off the TV, and do crossword puzzles or word games to help stimulate and maintain the brain.

By www.ALZinfo.org, The Alzheimer's Information Site. Reviewed by William J. Netzer, Ph.D., Fisher Center for Alzheimer's Research Foundation at The Rockefeller University.

Source:

Catherine M. Roe; Mark A. Mintun; Gina D'Angelo; Chengjie Xiong; Elizabeth A. Grant; John C. Morris: "Alzheimer Disease and Cognitive Reserve: Variation of Education Effect With Carbon 11--Labeled Pittsburgh Compound B Uptake," Archives of Neurology, Volume 65(11): November 11, 2008, pages 1467-1471.

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