Beagle study shows value of diet, exercise and stimulation in forestalling mental decline

Tuesday, January 25th 2005, 2:38 pm
By: News On 6

Perhaps people can learn some new tricks from old dogs in warding off the mental decline that comes with aging.

Those tricks include good diet, exercise and plenty of mental stimulation.

A study _ in which old beagles learn to win a shell game _ suggests that aging humans might benefit from improved diets and habits too, because dogs and people experience remarkably similar cognitive declines as they get older. Dogs even develop plaque deposits in their brains similar to the ones that can eventually lead to Alzheimer's disease in humans.

In this experiment, researchers taught old beagles to find treats under different colored boxes. The dogs that ate an enriched diet, got more exercise and had the benefit of toys and playmates were far more likely to figure it out.

Some studies have suggested that people can ward off or at least delay the mental effects of aging by eating a diet rich in antioxidants and other compounds found in fruits and vegetables. Other studies have found that exercise and mental stimulation may also have a protective effect.

But the beagle study is unique in looking at diet and behavior together.

``What I think is interesting about this study and somewhat different is the combination,'' said Molly Wagster, a program director at the National Institute on Aging. ``The combination effect is better than either thing alone.''

The study divided 48 beagles between the ages of 8 and 11 into four groups. One group got a twice-weekly workout, a regular rotation of toys, lived in a kennel with a roommate and ``went to school'' to learn how to find hidden treats. Another group ate a diet rich in antioxidants, but enjoyed none of the lifestyle benefits of the first group. A third group got both the antioxidant diet and the lifestyle benefits. And the last group got no special treatment.

The experiment is described in the January issue of Neurobiology of Aging. It involved researchers from the University of Toronto, the University of California Irvine, the Hill's Pet Nutrition Science and Technology Center and the Lovelace Respiratory Research Institute.

After two years of living in their different groups, all of the dogs were taught a trick that required them to find a treat under either a black or white box. For each it was always the same color, and all 48 dogs eventually learned that black (or white) meant a treat.

But that was just the old trick.

The researchers then switched boxes. If a dog had found its treat under the white box before, the morsel was hidden under the black one, and vice versa. Now the dogs had to figure out that they were playing the same game with the colors reversed.

All 12 of the dogs in the group with an enriched diet and high-stimulation environment learned the new trick.

``We were surprised to see that,'' said Elizabeth Head, one of eight collaborators on the experiment.

From previous experience, she said, ``we would have expected at least two to three of them not to be able to do this.''

The other three groups did not perform as well. Eight out of 12 dogs that ate an enriched diet alone figured it out, and eight out of 10 in the high-stimulation group solved the puzzle.

In the group that got neither a special diet nor a stimulating environment, only two out of eight dogs picked up on the color reversal.

Though the experiment was small, said Head, a professor of neurology at the University of California Irvine, ``these results are relatively striking.''

And because the treatments began when the dogs were already middle-aged, the study suggests that similar lifestyle change can improve the cognitive abilities of humans even when adopted fairly late in life.

``There's the indication that it's never too late,'' said Wagster. ``Which I think is a very important implication.''