How the Study with Beagles Was Done
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To carry out the study, the researchers divided a group of 48 older
beagles -- ages 7 to 11 -- into four groups, each receiving somewhat different care.
The four groups were as follows:
One group was fed a
regular diet and received standard care.
A second group received
standard care but was fed an antioxidant fortified diet, consisting of standard dog food
supplemented with tomatoes, carrot granules, citrus pulp, spinach flakes, the equivalent
of 800 IUs of vitamin E, 20 milligrams per kilogram of vitamin C, and two mitochondrial
co-factors—lipoic acid and carnitine.
The third group was fed
a regular diet, but their environment was enriched with such things as regular exercise,
socialization with other dogs, and access to novel toys.
Finally, the fourth
group received a combination of the antioxidant diet as well as environmental enrichment.
In addition, a set of 17 young dogs ranging in age from 1 to 3 were
divided into two groups, one fed a regular diet and the other fed the antioxidant
fortified diet.
The fruits and vegetables added to the antioxidant fortified diet
was the equivalent of increasing intake from 3 servings to 5 or 6 servings daily. Previous
research suggests that antioxidants might reduce free radical damage to neurons in the
brain, which scientists believe is involved in age-associated learning and memory
problems. Mitochondrial co-factors may help neurons function more efficiently, slash free
radical production and lead to improvements in brain function. Other studies suggest that
stimulating environments improve learning ability, induce beneficial changes in cellular
structure, may help the brain grow new neurons, and increase the resistance of neurons to
injury.
As the study progressed, researchers tested the dogs with a series
of increasingly difficult learning problems, including a task in which the animals needed
to learn whether a treat was hidden under a black or white block (black/white
discrimination). Later, the treat was hidden under the opposite block so the dogs had to
relearn the task (reversal learning).
What Was Discovered from Beagle Performance
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Overall, older dogs in the group with the combined
intervention did the best on these learning tasks, outperforming dogs in the control group
(standard diet, standard care)
as well as outperforming those that received
either the antioxidant diet or environmental enrichment. However,
the older beagles that received at least one of these interventions also did better than
the control group. |
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For instance, all 12 of the older beagles in the combined
intervention group were able to solve the reversal learning problem. In comparison, 8 of
the 12 dogs that ate the antioxidant diet without environmental enrichment and 8 of the 10
that received environmental enrichment without the antioxidant diet solved the problem.
Only two of the eight older dogs in the control group were able to do this task. Dietary
intervention in the younger canines had no effect.
“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,” says Dr. Head. “We're excited about
these findings because the interventions themselves are relatively simple and might be
easily translated into clinical practice for people.”
The NIA leads the Federal research effort on aging in general and on
aging and memory, including Alzheimer's disease. For more on these topics, visit the NIA's
websites. Information on Alzheimer's disease and memory may be viewed at www.alzheimers.org or call toll free at
1-800-438-4380. General information on health and aging may be viewed at www.nia.nih.gov . Publications may be ordered online at
www.niapublications.org or by calling the
NIA Information Center toll free at 1-800-222-2225.
This article was adapted by WorkingDogWeb.com from the NIA/NIH news
release seen here:
http://www.nia.nih.gov/NewsAndEvents/PressReleases/PR20040118Dogs.htm
SOURCE: Milgram, N.W., Head, E., Zicker,
S.C., Ikeda-Douglas, C.J., Murphey, H., Muggenburg, B., Siwak, C., Tapp, D., Cotman, C.W.
Learning ability in aged beagle dogs is preserved by behavioral enrichment and dietary
fortification: a two-year longitudinal study. Neurobiol Aging, 2005, 26: 77-90.
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