February 22, 1999
La Jolla, CA – Can regular exercise strengthen the brain? According to a new Salk study, animals that get regular voluntary exercise on running wheels grow more new brain cells than sedentary counterparts.
In the study, published in the February 25 issue of Nature Neuroscience, investigators separated mice into groups and for twelve days gave them a chemical that labels dividing cells. When the study ended, the mice on the move had the most new brain cells, twice as many as mice housed in standard cages.
“The difference was striking,” said Salk Professor Fred H. Gage, senior author on the study. “And because we know now that human brains also make new cells, it just might be that running or other vigorous exercise stimulates brain cell production in people as well.”
Gage’s laboratory recently overturned long-standing neuroscience dogma that stated we do not gain new brain cells after birth. They have also shown that mice raised in what they term “enriched environments” grow more new cells than litter mates housed in standard laboratory cages.
“Mice in the enriched environments were exposed to a number of variables, including toys, exercise wheels, a varied diet, and increased opportunities for social interaction,” said Henriette van Praag, a postdoctoral fellow in Gage’s laboratory and first author on the current study. “The present study is an attempt to tease out which type of stimulation is most important.”
In addition to the sedentary control group mice, two other groups designated “swimmers” were compared to the runners. These mice were placed for a brief period each day in a shallow pool. One of the groups had a learning task to accomplish, which the investigators thought might boost brain cell growth, and the other group simply had “free swim” time. Neither group displayed brain cell numbers comparable to the “runners.”
“We don’t know if it’s the voluntary factor that’s key – that is, the running mice were free to jump on or off the wheel as they liked – or if it’s because the swimmers simply got less exercise,” said Gage.
He also pointed out that learning a specific task might stimulate changes in existing brain cells rather than boost the growth of new cells.
So, are the mobile mice smarter?
“We don’t have the answer to that yet,” said Gage. “But it seems reasonable to think they might be – the new cell growth takes place in the part of the brain called the hippocampus, which has been linked by many studies to learning and memory. And the enriched environment mice in previous studies performed better on learning tests.”
He added that experiments are currently underway to directly assess the effects of running on learning ability.
Co-author on the study is Gerd Kemperman, formerly a postdoctoral fellow in Gage’s laboratory and currently at the University of Regensburg in Germany. The work was supported by the National Institutes on Aging, the National Institute of Neurological Disorders and Stroke, the Pasarow Foundation, the Hollfelder Foundation, and the American Paralysis Foundation.
The Salk Institute for Biological Studies, located in La Jolla, Calif., is an independent nonprofit institution dedicated to fundamental discoveries in the life sciences, the improvement of human health and conditions, and the training of future generations of researchers. The Institute was founded in 1960 by Jonas Salk, MD, with a gift of land from the City of San Diego and the financial support of the March of Dimes Birth Defects Foundation.