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Dog study may help humans as they age

4/28/2005

Regular exercise, mental stimulation and a diet rich in antioxidants can help keep the brain sharp in older dogs — and perhaps do likewise in humans — according to a new study.

Researchers found that dogs ages 7 to 11 performed better on cognitive tests and were more likely to learn new tasks when fed a diet fortified with fruits, vegetables and vitamins, got exercise at least twice a week and played with other dogs and stimulating toys.

The study, done over two years, was conducted by scientists at the University of California-Irvine and the University of Toronto. It was published in the January issue of the journal Neurobiology of Aging.

"This research brings a note of optimism that there are things we can do that may significantly improve our cognitive health,'' said Molly Wagster, program director for neuropsychology of aging at the National Institute of Aging, which sponsored the study.

"While we have yet to demonstrate these benefits in people, research such as this gives us new ways to think about the aging brain and what we can do to keep it intact.''

Dogs are useful models for human-brain aging because they have more complicated brain structures than many other animals and, like people, engage in complex thinking strategies.

Like their masters, dogs also are susceptible to age-related declines in learning and memory, and can develop brain lesions similar to those seen in human Alzheimer's disease.

"The combination of an antioxidant diet and lots of cognitive stimulation — which was almost the equivalent of going to school every day — really did improve brain function in these animals,'' said Elizabeth Head, one of the researchers at the University of California-Irvine.

"We're excited about these findings because the interventions themselves are relatively simple and might be easily translated into clinical practice for people.''

For the study, 42 older beagles were divided into four groups. One received standard care and diet; another just got dog food fortified with vegetables and citrus pulp, and vitamins E and C supplements; a third just received extra exercise and social play, and a fourth got both the improved diet and exercise-play routine.

Fruits and vegetables added to the food was equal to increasing the human daily intake from three servings to five or six, a formula guided by other studies that show antioxidants can reduce age-related damage to the brain.

In the study, the dogs were challenged with increasingly difficult learning problems. The hardest task was finding a treat under a certain black-colored block and then relearning that task with a different color (white).

All 12 dogs getting the combined diet and exercise program were able to solve the reversed learning problem, but only two of the eight in the control group could do so. However, eight of the 12 on the enhanced diet alone and eight of the 10 on the exercise-play routine were able to solve the learning problem.

"In this case, more was better,'' said Wagster. "Although each (intervention) factor alone was capable of improving cognitive function in older animals, the combination was additive, pointing to a healthy lifestyle as the most beneficial approach.''