Exercise vs. calorie restriction for brain aging


As of September 2017, new Sweat Science columns are being published at www.outsideonline.com/sweatscience. Check out my bestselling new book on the science of endurance, ENDURE: Mind, Body, and the Curiously Elastic Limits of Human Performance, published in February 2018 with a foreword by Malcolm Gladwell.

- Alex Hutchinson (@sweatscience)


One of the clearest signs that you’re getting older, microscopically speaking, is that your synapses start to degenerate. This means that signals from your brain have a harder time getting through to your muscles (for neuromuscular synapses) and to other parts of the brain (for brain synapses). Harvard researchers decided to investigate how exercise and calorie restriction — “among the most effective anti-aging treatments known” — affect the age-related changes in mouse neuromuscular synapses (PNAS abstract here, press release here). The results:

“With calorie restriction, we saw reversal of all aspects of the synapse disassembly. With exercise, we saw a reversal of most, but not all,” [lead researcher Joshua] Sanes says.

Score one for calorie restriction? Not so fast…

Because of the study’s structure — mice were on calorie-restricted diets for their whole lives, while those that exercised did so for just a month late in life — Sanes cautions against drawing conclusions about the effectiveness of exercise versus calorie restriction. He notes that longer periods of exercise might have more profound effects, a possibility he and [Jeff] Lichtman are now testing.

That makes me hope that, with longer and more consistent exercise, we might one day discover that all the benefits of calorie restriction are in fact available from consistent and vigorous exercise. (That being said, a month in a mouse’s life does correspond to a considerably longer period in human terms. The “old” mice were about two years old.)

On a somewhat related note, another just-published study found a correlation between how much blood your heart can pump and how quickly your brain ages. The study didn’t include anyone with heart disease, so it applies to people with normally functioning hearts: the more blood you can pump, the more blood gets to your brain, and the less the brain shrinks. The study can only measure correlation, not causation — but it sounds like more confirmation that aerobic exercise is the best “brain training” around.

One Reply to “Exercise vs. calorie restriction for brain aging”

  1. All my relatives say: “You used to be so active. What’s happened?” My answer is “I am suffering from AD.”

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