December 17, 2008
People who have more years of schooling and who work in mentally demanding jobs are less likely to have memory impairment as they age, a new study shows. The findings are consistent with earlier research showing that the more years of formal education someone has, the lower the risk of Alzheimer's disease. Studies also suggest that doing mentally challenging tasks, like learning a new language, playing word games or doing Sodoku puzzles, can help to keep the brain young as we age.
"The theory is that education and demanding jobs create a buffer against the effects of dementia on the brain, or a cognitive reserve," said study author Dr. Valentina Garibotto of the San Raffaele University and Scientific Institute and the National Institute of Neuroscience in Milan, Italy. "Their brains are able to compensate for the damage and allow them to maintain functioning in spite of damage."
The study, which appeared in Neurology, the medical journal of the American Academy of Neurology, involved 242 men and women with Alzheimer's disease; 72 people with mild cognitive impairment, a form of memory loss that often precedes Alzheimer's; and 144 people with no memory problems. Mild cognitive impairment is marked by memory problems that are more severe than the normal age-related memory loss, but less serious than the problems that occur in Alzheimer's. Each year, about 12 percent of people with mild cognitive impairment go on to develop Alzheimer's disease. However, some 20 to 50 percent of people with mild cognitive impairment remain stable over the long-term and some even revert to a normal cognitive state.
The researchers tested the participants' memory and thinking skills using standard psychological tests. They also used brain scans to measure how glucose, or blood sugar, is taken up in the brain. The tests are a good indication of how much the brain has been damaged by beta-amyloid and tau tangles, abnormal proteins that build up in the brains of those with Alzheimer's disease.
The participants were followed for an average of 14 months. During that time, 21 of the 72 people with mild cognitive impairment went on to develop Alzheimer's disease.
The researchers found that in people with the same level of memory impairment, people with more education and more mentally demanding jobs had significantly more changes and damage in their brains from Alzheimer's disease than people with less education and less mentally demanding jobs. The more educated people, though, tended to develop the disease somewhat later in life.
These observations suggest that more educated people who hold mentally demanding jobs were better able to sustain a greater level of brain changes associated with Alzheimer's before these changes resulted in cognitive decline. In other words, more educated people may have a higher brain reserve that is able to ward off symptoms longer than people in the less educated group. This may translate into delaying the disease until a slightly later age for people with more education.
These findings are consistent with a previous study showing that more educated people tend to decline faster once they are diagnosed with Alzheimer's. That could be a result of having greater brain deterioration and more advanced disease at the time when cognitive symptoms first appear.
The researchers note that the brain could be made stronger through education and occupational challenges that build up brain cells and the connections between them -- or cognitive reserve. Later in life, the theory goes, these connections may help compensate for the risk in dementia-related brain defects that occur with normal aging, or with diseases like Alzheimer's. Alternatively, it may be possible that the same genetic factors that enable people to achieve higher education and occupational achievement might determine the amount of brain reserve.
People with Alzheimer's disease and people with mild cognitive impairment who developed Alzheimer's during the study had abnormal glucose readings in areas of the brain consistent with Alzheimer's disease. In contrast, people without memory problems and those with mild cognitive impairment who did not develop Alzheimer's disease had no brain metabolism problems.
Source: V. Garibotto, MD; B. Borroni, MD; E. Kalbe, PhD; et al: "Education and Occupation as Proxies for Reserve in aMCI Converters and AD.: PDG-PET Evidence." Neurology, Volume 71, October 20, 2008, pages 1342-1349.