“We thought we would find gains from exercise and also from mindfulness and especially from a combination of the two,” said Eric Lenze, chief of the department of psychiatry at Washington University School of Medicine in St. Louis, who led the new study. .
The findings appear to question the ability of exercise and other lifestyle changes to combat cognitive decline with aging. But they also raise new questions about whether we really understand the brain and mind enough – or how to study them – to know if we change them when we walk or meditate.
“Given that other studies have found a significant relationship between mindfulness and exercise and cognitive and brain health, how do we explain the current findings?” wondered Art Kramer, director of the Center for Cognitive & Brain Health at Northeastern University in Boston, who has studied exercise and the brain extensively but was not involved in the new study.
The answers may have implications for all of us who hope physical activity helps keep our minds sharp well into middle age.
Previous studies have shown that exercise helps brain health
Certainly, plenty of previous research suggests that our lifestyles influence our brain health. Exercise, in particular, seems to play a key role in how we think and remember as we age. A 2011 review of previous studies concluded that “there is growing evidence that aerobic training and resistance training are important for maintaining cognitive and brain health in older adults.”
Reinforcing this claim, a famous 2011 study of 120 older men and women found that those who started moderate exercise, mostly walking, had improved memory test scores and increased hippocampus size. , a part of the brain crucial for memory function, while those in a sedentary control group experienced a decline in their hippocampal volume and memory abilities.
Likewise, mindfulness has been linked to improvements in some aspects of memory and thinking in older adults, likely because it helps reduce stress and distractions.
But much of that research was short-term and small-scale, involving perhaps a few dozen participants, or it was epidemiological, meaning it found suggestive links between physical activity or mindfulness. and sharper minds, but has not been shown to directly improve people’s brains.
A new study on exercise, mindfulness and the brain
Which makes the new study remarkable. As of 2015, its authors, primarily based at the University of Washington or the University of California, San Diego, recruited 585 healthy but inactive men and women between the ages of 65 and 84. None of the participants had been diagnosed with dementia, but all told the researchers they were worried. their thoughts and memories were duller than before.
The scientists tested everyone’s thinking skills, focusing on attention, working memory and word or picture recall, and also scanned their hippocampal volume, then randomly assigned them to different groups. . One started training twice a week in 90-minute supervised exercise classes, alternating between walking or similar aerobic activities, light training and balance practice. After six months, they took their routines home, exercising mostly alone for about an hour a day for another year.
A second group learned mindfulness-based stress reduction, combining meditation, yoga and mental exercises, under supervision for six months and on their own the following year. A third group exercised and meditated several times a week, while a control group took classes twice a week on healthy lifestyles.
After six months and again after 18 years, the researchers repeated the cognitive tests and brain scans.
By the end, almost everyone’s hippocampus volume had shrunk, whether they were exercising, meditating or not.
At the same time, their cognitive scores increased slightly, a universal — but misleading — improvement, Lenze said. If exercise or meditation had actually benefited people’s brains, their scores should have been higher than those of the control group. Because they weren’t, he said, he and his colleagues attribute any gains to “people getting better at passing the tests.”
What this means for athletes and the aging brain
So, do the results indicate that training and mindfulness are unnecessary for brain health?
“I think this study is telling us that we don’t know as much about the brain as we think we do,” Lenze said.
Exercise and mindfulness didn’t improve some cognitive tasks in this study, he said, but maybe they would help other types of thinking or maybe their effects would be different in people. people with more or less significant memory problems.
“I think the authors did a very rigorous study,” said Teresa Liu-Ambrose, director of the Center for Brain Health at the University of British Columbia in Vancouver, which studies exercise and the brain, but does not was not part of this research.
But she also questioned the narrowness of specific tests and analyzes used to measure changes in people’s thinking skills.
So does Mark Gluck, professor of neuroscience at the Center for Molecular and Behavioral Neuroscience at Rutgers University in Newark. “If the researchers had used more sensitive behavioral measures” of how people think and remember, he said, “their reported results might well have been very different.”
Other brain scanning techniques could also have discerned significant changes in people’s brains at the end of the study, he said.
Overall, the results of the new study “importantly suggest that future studies should carefully examine the characteristics of the populations studied” and the exercise and mindfulness routines used, “to resolve ambiguity” as to whether and how they affect aging minds, Kramer said.
What the results don’t suggest is that exercise or meditation is futile, Lenze said. “We don’t want people to get the message that they shouldn’t exercise.”
Exercise and mindfulness remain beneficial, he said, and he practices both.
Future studies may, after all, detect unobserved benefits in this experiment. “There is still so much to learn about the brain,” he says.
Do you have a fitness question? E-mail YourMove@washpost.com and we may answer your question in a future column.
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