September 20, 2005

Exercise may reverse mental decline brought on by aging

Salk News

Exercise may reverse mental decline brought on by aging

La Jolla, CA – Perhaps you can teach an old mouse new tricks, after all. But be sure to pick an active one.

In a paper appearing September 21 in The Journal of Neuroscience, scientists at the Salk Institute for Biological Studies show that mice that voluntarily started exercising in old age were better able to learn new tasks and added more of the brain’s message-relaying neurons than their sedentary counterparts.

“Our findings show it is never too late in life to start to exercise,” says author Henriette van Praag, PhD, “and that doing so will likely delay the onset of aging-associated memory loss.”

A slow-down in the growth of new neurons and in mental ability is associated with normal aging, but the 19-month-old mice in the study (equivalent to an older person) were able to reverse this decline-adding up to 50 percent as many new neurons as young, sedentary mice-after using a running wheel for a month. Furthermore, the new neurons appeared to function as well as those in the brains of young mice.

The Salk team, led by Fred H. Gage, PhD, also noted that young mice that exercised showed the greatest neuron growth of all the groups. “It is possible that earlier onset of running would have maintained cognitive function to an even greater extent,” they wrote.

Were the older mice able to perform the learning task better simply because they were more fit? Or because their brain function really improved? The Gage team address these points in their study, yet the extent to which new neuron growth contributes to the ability to learn and remember remains to be confirmed.

“Nonetheless, a good case is made for a cognitive effect correlated with the neurogenesis,” says Bill Greenough, PhD, of the University of Illinois. “This is an important finding.”

The study also points to promising areas for future research on human aging and mental health, such as what brain signals mediate the effect of exercise and the association between learning and neuron birth in the area of the brain that handles memory, says Ira Black, MD, of the University of Medicine and Dentistry of New Jersey.

“These findings serve to integrate environmental factors and brain functioning. This represents a very first step, but the findings raise possibilities in approaches to learning in the elderly,” he says.

The Society for Neuroscience is an organization of more than 36,000 basic scientists and clinicians who study the brain and nervous system.

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