These supplements, acetyl-l-carnitine and alpha lipoic acid, are continuing to be studied in work with humans, and scientists believe they may provide a new approach to the neurodegeneration and cognitive decline common with aging.
The newest study was just published in FASEB Journal, produced by the Federation of American Societies for Experimental Biology, by researchers from the Linus Pauling Institute at Oregon State University, the University of Toronto, University of California/Berkeley, Children’s Hospital Oakland Research Institute, and Juvenon, Inc.
It found that supplements of these two antioxidant compounds, which are believed to play a role in slowing mitochondrial decay in the cell, significantly increased the ability of “geriatric” beagle dogs to learn a new task.
The study builds on similar findings made several years ago, done with mice and published in Proceedings of the National Academy of Sciences. In that research, the activity and energy level of old rats taking these same supplements almost doubled, and memory and cognitive function improved.
“The prospects for cognitive improvement from use of these supplements is both fascinating and exciting,” said Tory Hagen, an associate professor in OSU’s Linus Pauling Institute, and recognized expert on the biological processes of aging.
“This is the first time these two compounds, by themselves, have been tested in canines, which have brains that are more biologically similar to humans than some other animal models,” Hagen said. “The results should be relevant to what we could expect with humans, and are very encouraging.”
In this study, an inbred line of older, very similar beagle dogs were taught how to find a food treat by identifying certain markers, such as a yellow wooden peg. Applied scents were used to control for any tip-off by sense of smell. Some dogs received short-term dietary supplementation with acetyl-l-carnitine and lipoic acid, and others did not.
On one task, four of six dogs receiving supplements quickly learned to find the food treat by identifying the correct marker, while only two of six dogs on normal diet succeeded. After 15 more weeks of training, more than 80 percent of supplemented dogs were successful, while only 50 percent of those not receiving supplements could learn the new task.
“We’ve shown in some previous animal work that these supplements could improve memory and energy level,” Hagen said. “Now we’re seeing that animals receiving supplements are much more readily able to learn new things as well, even at an advanced age.”
In these tests, the effects of supplementation with these compounds appeared to work fairly quickly, in a matter of days or weeks, the scientists said. Some other studies, however, have required much longer periods of supplementation for various antioxidants to improve cognitive performance.
Humans also experience loss of the type of object and spatial discrimination that was improved by supplements in these animal tests – it’s often one of the early signs of human dementia.
The scientists suggested in the paper that long-term supplementation “may be effective in attenuating age-associated cognitive decline by slowing the rate of mitochondrial decay and cellular aging.” Enhancing the function of mitochondria - which provide almost all of a cell’s energy - could literally be providing animals with more “mental energy,” leading to improved memory and learning, the study indicated. The compounds may also cause increased synthesis of a neurotransmitter called acetylcholine.
An increasing body of research suggests that mitochondria may be an “Achilles heel” for absorbing age-related damage, as part of the natural process of oxidation in the body and the related “free radicals” that are produced and can cause cellular damage. As the power plant of cells, mitochondria perform many of the roles critical to cell function, use up to 90 percent of the oxygen humans breathe, but are also among the first cellular components to be damaged by reactive radical oxygen species.
This study was funded by private industry, including companies that produce the compounds being studied.
Clinical experiments with humans using these supplements are already under way, scientists said.
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