For the first time, scientists have shown that learning slows the build-up in the brain of protein plaques and tangles that are the signature of Alzheimer's disease.
Although the study was conducted in mice, it does reinforce the idea that, in humans, maintaining an active mind may help delay or even prevent Alzheimer's disease.
"This has shown for the first time that using your brain can protect you physically," said Kim Green, co-lead author of the study and a postdoctoral researcher at the University of California, Irvine. "We show that when you do this, it causes changes in the brain, and these changes are protective."
"It's an interesting study, and part of what it does is advance the notion that mental exercise has a protective effect against Alzheimer's," said Dr Gary Kennedy, director of geriatric psychiatry at Montefiore Medical Center in New York City.
Many experts believe that Alzheimer's is caused by a steady accumulation of amyloid plaque proteins in the brain.
Previous studies had shown that "mental exercise" could delay the onset of the disease, but the proof came only in the form of memory and other cognitive testing measures.
The authors of this study, which is published in the Jan. 24 issue of the Journal of Neuroscience, wanted to see if there was a biological correlation for those encouraging results.
How the research was done
The study involved hundreds of "transgenic" mice - mice that had been genetically altered to develop human Alzheimer's disease.
Mice in a "learning" group were allowed to swim in a tank of water until they discovered a submerged platform on which to stand. This training took place four times a day for one week at two, six, nine, 12, 15 and 18 months of age. The other group of mice swam in the tank just once before their learning and memory skills were tested and their brains examined.
Mice up to 1 year old in the learning group developed 60 percent less of the proteins that form plaques and tangles compared to mice in the non-learning group, the researchers found.
"The sort of learning we gave the animals was fairly mild, yet it still had a big effect," Green said.
However, by 15 months of age, the learning mice had declined and were now physically and cognitively identical to the non-learning mice.
From mice to humans
Can these findings be extrapolated to humans?
"We do find a lot of similarities, but clinical data also backs up what we've shown in this study," Green said.
"I think it's reasonable to extrapolate," Kennedy added. "The recommendation certainly is to keep your mind active."
"Think of the brain as a computer," Kennedy continued. "Alzheimer's degrades the hardware, and education enhances the software. The brain is also a muscle, and conditioning may protect it."
Green and his colleagues hope to use the information to one day develop a drug for the disease.
"We want to identify exactly how learning influences pathology and identify a novel drug target," he said. - (HealthDayNews, January 2007)
Learning slows Alzheimer's