“We thought we would find benefits from exercise and also from mindfulness, and especially a combination of the two,” said Eric Lenze, head of the department of psychiatry at Washington University School of Medicine in St. Louis. Louis, who led the new study.
The results seem to call into question the ability of exercise and other lifestyle changes to combat cognitive decline with age. 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.
“Since other studies have found a significant relationship between mindfulness and exercise and cognitive and brain health, how can we explain the current results?” asked Art Kramer, director of the Center for Cognitive and 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 any of us who hope that physical activity will help keep our minds sharp beyond middle age.
Past research has shown that exercise helps brain health
Certainly, a wealth of past research suggests that our lifestyle affects our brain health. Exercise in particular seems to play a key role in how well we think and remember as we age. In 2011 review of earlier studies concluded, “there is increasing evidence that both aerobic and resistance training are important for maintaining cognitive and brain health in old age.”
Supporting this claim, the famous 2011 study of 120 older men and women showed that those who began moderate exercise, mostly by walking, improved their scores on memory tests and increased the size of their hippocampus, a part of the brain critical to memory function, while those in a sedentary control group experienced a decline in their hippocampal volume and memory skills.
Similarly, mindfulness is associated with improvements in some aspects of memory and thinking in the elderly, possibly because it helps reduce stress and distraction.
But much of this research was short-term and small-scale, involving perhaps a few dozen participants, or epidemiological, meaning it found suggestive links between physical activity or mindfulness and a sharper mind, but did not prove that they directly improve the human brain.
A New Study of Exercise, Mindfulness, and the Brain
Which makes the new study noteworthy. Starting in 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 abilities, focusing on attention, working memory and recall of words or pictures, and also scanned their hippocampus volume, then randomly assigned them to different groups. One began exercising twice a week in supervised, 90-minute exercise classes, alternating between walking or similar aerobic activity, light weight training, and balance exercises. After six months, they took their routines home, practicing mostly on their own for about an hour a day for another year.
Another group learned mindfulness-based stress reduction, combining meditation, yoga and mental exercises, under supervision for six months and independently for the next year. The third group both exercised and meditated several times a week, while the control group attended courses on healthy living twice a week.
After six months and again after 18, the researchers repeated the cognitive tests and brain scans.
By the end, almost everyone had a reduction in hippocampal volume, regardless of whether they exercised, meditated or not.
At the same time, their cognitive scores rose slightly, a universal — but misleading — improvement, Lenze said. If exercise or meditation really benefited the human brain, their results should be higher than those of the control group. Since they haven’t, he said, he and his colleagues attribute any gains to “people getting better at taking tests.”
What this means for exercisers and the aging brain
So do the results show that exercise and mindfulness are meaningless for brain health?
“I think what this study tells us is that we don’t know nearly as much about the brain as we think we do,” Lenze said.
Exercise and mindfulness didn’t improve certain cognitive tasks in this study, he said, but they might help other kinds of thinking, or maybe their effects would differ in people with more or less 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, who studies exercise and the brain but was not part of the research.
But she also questioned the limitations of the specific tests and analyzes used to measure changes in people’s thinking skills.
So did Mark Gluck, a 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 well people think and remember, he said, “their results might have been quite different.”
Other brain scanning techniques were also able to detect significant changes within people’s brains by the end of the study, he said.
Overall, the results of the new study “importantly suggest that future studies should carefully consider the characteristics of the study populations” and the exercise and mindfulness routines used, “to resolve the ambiguities” about whether and how they affect the aging mind, Kramer said. .
What the findings don’t suggest is that exercise or meditation are futile, Lenze said. “We don’t want people to get the message that they shouldn’t exercise.”
Both exercise and mindfulness remain useful, he said, and he exercises.
Future studies may, after all, reveal benefits not seen in this experiment. “There is still so much to learn about the brain,” he said.
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