The learned mind’s edge on Alzheimer’s

Building on evidence that those who challenge their minds reap the rewards in old age, a new study has found that extra years of schooling appear to allow Alzheimer’s patients to function better and longer than those with less schooling.

The finding suggests that education, and the mental fitness it seems to set into motion, may boost mental resilience, even when a mind is under assault by disease, experts say. An earlier study had found that people who reached higher levels of regular mental stimulation -- reading books and newspapers, doing crossword puzzles, going to museums -- appeared to have lower rates of Alzheimer’s disease.

Dr. David A. Bennett, a professor of neurological sciences at Rush University in Chicago, called education levels in this study “a proxy” for the mental stimulation that individuals maintain and the ways in which they process complex information. An academic degree off a matchbook would not necessarily trump a lifetime of informal learning, he said.

“We don’t think it’s the degree -- it’s what you had to do to get it,” says Bennett, who directed the study, which appeared in the June 24 issue of the journal Neurology.

The findings come from the Religious Orders Study, which has tracked 900 older nuns, priests and brothers scattered across the United States since 1993. Participants enrolled without symptoms of dementia, submitted to yearly exams of their physical health and mental acuity, and agreed to donate their bodies for autopsy. While the schooling of members of these Catholic orders ranged from completing sixth grade to receiving doctoral degrees, the 130 participants had on average 18 years of education -- about two years of postgraduate work.

After examining the brains of these deceased patients and reviewing their performances on earlier cognitive tests, researchers at Rush-Presbyterian-St. Luke’s Medical Center found something remarkable: Even among those whose brains were riddled with the amyloid plaques characteristic of Alzheimer’s, memory and intellectual function were better in the participants with more schooling. The less schooling an individual had, the more pronounced were the negative effects of Alzheimer’s.

“It may be that education permits the brain already affected by the pathology of Alzheimer’s disease to work around that damage and allow an individual to function at a higher level,” said Neil Buckholtz, chief of the National Institute on Aging’s dementias branch. The study was conducted with federal funds distributed by the institute, an organization within the National Institutes of Health.

Amyloid plaques are hard clusters of protein fragments and cellular debris that form in the parts of the brain responsible for memory and some higher intellectual function. Researchers also looked at a second indication of Alzheimer’s -- neurofibrillary tangles, or knots of proteins that seem to damage neurons themselves -- but they failed to find that a person’s level of education countered the effects of the tangles.

Researchers knew at the outset that an individual’s performance on cognitive tests tended to go up or down with his or her educational level. But they found that the differences in intellectual function between the more- and less-educated were even more pronounced as the numbers of amyloid plaques increased.

For instance, once amyloid plaques had invaded the brains of an 84-year-old woman with some college attendance and a second 84-year-old who had done post-graduate work, the initially modest gap between the two women’s performance on cognitive tests widened considerably. When each woman had roughly 12 plaques -- more than the number required to diagnose Alzheimer’s disease -- the more highly educated woman’s cognitive-test score dropped from 98.1 to 96.2; the less-educated woman’s score fell 14 points, from 96.2 to 82.

“It’s not simply that [with different education levels] you start at different levels, but you diverge sharply as pathology accumulates,” Bennett said.

Her brain under attack by amyloid plaques, the less-educated woman “not only has a shorter distance” to reach the point of dementia, but “she’s moving there more quickly,” he said. “And that’s a race you want to lose.”

Bennett and his co-authors plan future studies, drawing from a sampling of Americans across a broader spectrum of socioeconomic strata and occupations.

Bennett said that as researchers learn more about the ways that life and learning styles modify the manifestations of such diseases as Alzheimer’s, the likelihood of treatments will grow. Some interventions -- such as mental gymnastics -- may do little more than forestall the onset of dementia in cases where the physical manifestations of Alzheimer’s, like amyloid plaques, have already made inroads. But for people with the disease, and those who care for them, a few extra years of clear-mindedness are nothing to sneer at, he said.

“Imagine if you could find ways to strengthen the brain so that the burden of the disease would have to be extremely heavy before you begin to get the debilitating symptoms,” Bennett said. “It would be big.”