What's Best For Your (Aging) Brain

A new study by the USC Davis School of Gerontology's Elizabeth M. Zelinski makes a surprising finding after analyzing 42 studies
By Jonathan Riggs

Elizabeth Zelinski, Ph.D.

Conventional wisdom and popular science suggest many solutions to keeping our minds sharp as we age: medications, physical exercise, brain games. But which is truly best?

In a new article published in the Journal of the American Geriatrics Society, the USC Davis School of Gerontology’s Elizabeth M. Zelinski, Ph.D. describes findings from her National Institute on Aging-funded meta-analysis of 42 studies with 3,781 healthy older adults aged 55 and older.

Inspired by Zelinski’s previous work on the influential IMPACT (Improvement in Memory with Plasticity-based Adaptive Cognitive Training) Study published in 2009, the article, “Extended Practice and Aerobic Exercise Interventions Benefit Untrained Cognitive Outcomes in Older Adults: A Meta-Analysis,” co-authored with her doctoral student Shoshana B. Hindin, examined the question of how much aerobic exercise improves cognition compared to cognitive exercise.

“In research studies that examine cognitive outcomes, one of the things we know is that you have to be very careful in interpreting findings of improvements—people get better at tasks like remembering lists of words just from doing them a few times,” Zelinski said. “So it looks like the training was effective, but we need to do two things to be sure.”

First, she said, there must be a control group of people who don’t get the training. If they improve on the tests, then Zelinski knows that the training isn’t the only thing that is helping: the practice they get in taking the test is important. The second thing is to see if getting training improves performance on something other than what was trained, which is called transfer. The training “transfers”—or works—to help cognition more generally. For example, if a subject were trained on a task like reciting an increasingly long list of numbers in the reverse order from which they were read, that helps the subject to expand the amount of information they can hold in their mind.

“But is it going to help you remember something rather different later, like a grocery list?” she said. “In our study, we were looking to see improvements not in the activities that were trained, but those that had not been trained. ”

By taking away the effects of practice in taking the same tests before and after the training, Zelinski found that there was no difference in the benefits of aerobic and cognitive exercise.

“The reviewers asked, ‘So what are you going to tell the press—that you don’t have to do physical exercise?’” she said. “No. Cognitive and aerobic exercise have similar effects in improving performance on tasks people weren’t trained on, but we don't know what happens when you put the two together. Besides, it’s really a good thing to exercise for many other health reasons.”

Acknowledging that the team has a long way to go in understanding what the specific sources of the effects are, she described how they compared the improvements of aerobic exercise or cognitive training to those of a medication on cognitive tests similar to those used in the training studies—Provigil, to be specific, which is used off-label to increase attention and working memory. The results were surprising: the benefits weren’t that different at all.

“This tells us that there are different routes to the same outcome, but it doesn’t mean that one route is better than another. At the end of the day, one of the things we know for sure is that people need to exercise—it’s associated with so many cardiac benefits, and reduced risk of strokes and dementia,” she said. “Physical exercise is good to do. Cognitive exercise may also be related to other benefits, like being better at remembering to take medications or to make good eating choices or to take a walk. You needn’t give up one in favor of the other.”

Instead, Zelinski points to the fact that not everyone is physically capable of exercising, and this news might be reassuring to those persons in terms of their ability to fend off declines in cognitive performance.

As the study focused solely on healthy people and not those diagnosed with dementia, Zelinski emphasized the need for additional studies and clinical trials but spoke of the research accomplished in this meta-analysis with pride.

“It shows that older people can improve their cognition and in different ways,” she said.