Does exercise destroy memories? New research contradicts 2014 study

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Exercise causes more new neurons to be formed in a critical brain region, according to research by Texas A&M College of Medicine scientists, in the Journal of Neuroscience.

Contrary to an earlier study, these new neurons do not extinguish older memories, the study says.

Exercise is well known for its cognitive benefits, thought to occur because it causes neurogenesis, or the creation of new neurons, in the hippocampus, which is a key brain region for learning, memory and mood regulation.

Many scientists were surprised in 2014 when a research study, published in the journal Science, found that exercise caused mice to forget what they’d already learned.

“It stunned the field of hippocampal neurogenesis,” said Ashok K. Shetty, a professor in the Department of Molecular and Cellular Medicine, associate director of the Institute for Regenerative Medicine, and research career scientist at the Central Texas Veterans Health Care System. “It was a very well-done study, so it caused some concern that exercise might in some way be detrimental for memory.”

In the 2014 study, mice in the exercise group showed far more neurogenesis than those in the control group. However, these additional neurons seemed to erase memories that were formed before the mice started the exercise regimen. To test this, the researchers removed the extra neurons, and the mice suddenly were able to remember again.

Shetty and his team decided to replicate the study, but used rats as models instead of mice. Rats are thought to be more like humans physiologically, with more-similar neuronal workings. The A&M researchers found the rats showed no such degradation in memories.

“We had completely contradictory findings from the 2014 study,” said Maheedhar Kodali, a postdoctoral fellow at the Institute for Regenerative Medicine and the first author of the A&M study. “Now we need to study other species to fully understand this phenomenon.”