Faced With Cognitive Impairment, Brain Enlists New Areas

Memory training can help people with mild cognitive impairment—a psychological state often preceding Alzheimer's disease. But the improvements do not appear to be any better than those that could be obtained with, say, a discussion of art or politics.

This was the conclusion described by researchers on January 19 in the Cochrane Reviews after analyzing studies conducted on the subject between 1970 and 2007.

But they did include this more auspicious addendum: "This does not mean that longer, more intense, or different interventions might not be effective, but that those which have been reported thus far have only limited effect."

Now another study on the subject has been published—in the June Brain—by a group of Canadian scientists. It was not a randomized, controlled trial designed to test the efficacy of memory training, but rather a memory-training/brain-scanning study intended to explore how memory training affects the brains of people with mild cognitive impairment.

Credit: Sylvie Belleville, Ph.D., et al.

The study, which was headed by Sylvie Belleville, Ph.D., director of the University of Montreal's Institute of Geriatrics, included 30 older adults—15 with mild cognitive impairment and 15 matched healthy controls. (In a previous study, Belleville and her colleagues had found that while some people with mild cognitive impairment seem to remain stable or even return to normal over time, more than half progress to Alzheimer's within five years.)

Subjects were first asked to remember certain words, and while they were remembering those words, fMRI scans were made of their brains. During the next six weeks, subjects were given memory training. They learned different mnemonics and techniques to promote memory encoding and retrieval. At the end of that time, they were again asked to remember certain words and again fMRI scans were made of their brains. Finally, the scan results for the mild cognitive impairment group were compared with those for the control group.

When presented with a memory challenge before memory training, both the mild cognitive impairment and control groups showed activation of frontal and parietal regions typically involved in memory, notably the hippocampus. And when presented with a memory challenge after training, both groups showed activation in the same areas as well.

But in addition, the mild cognitive impairment group showed activation in other brain areas—for example, the left temporal lobe (which is involved in language processing), the right prefrontal and parietal areas (involved in spatial and object memory), and the cerebellum and basal ganglia (involved in skill learning).

These findings thus suggested that memory training enabled the mild cognitive impairment subjects to recruit new brain areas that they would not have otherwise used in the remembering process. And as Belleville and her colleagues pointed out in their report, "The newly recruited brain regions are those involved in the types of strategies that participants learned to implement." In brief, "Memory training normalizes the brain activation deficits associated with mild cognitive impairment."

Some important questions remain to be answered, though, Belleville and her group acknowledged. For instance, are the brain changes that the researchers found specific to the particular memory training program they used, or would the changes also be triggered by other types of memory training programs?

In any event, their findings indicate that the brains of people with very early Alzheimer's are still quite plastic and "able to recruit new neural circuits to perform demanding memory tasks," they concluded. "The findings also provide empirical support for the use of cognitive training as a potential treatment for people with memory difficulties," they added.

"Obviously these findings need to be replicated in diverse samples before they can be considered as established," Dilip Jeste, M.D., a professor of psychiatry at the University of California, San Diego, a geriatric psychiatrist, and president-elect of APA, said in an interview. "Nonetheless, the results are exciting as they help challenge the traditional notion that the aging brain, especially in people with mild cognitive impairment, is incapable of positive changes such as greater activation following cognitive nonpharmacological interventions."

Belleville and her team will be conducting more research on this subject, she told Psychiatric News. "One will be a large-scale, randomized controlled trial comparing the efficacy of cognitive and psychosocial interventions in mild cognitive impairment and investigating their long-term effect on cognitive decline and progression to dementia and their effect in daily life."

The study was funded by Research Health Funds of Quebec, the University of Montreal Institute of Geriatrics, and the Canadian Institutes for Health Research.

An abstract of "Training-Related Brain Plasticity in Subjects at Risk of Developing Alzheimer's Disease" is posted at <http://brain.oxfordjournals.org/content/134/6/1623.abstract>.