"In the study we subjected 45 senescent rats-meaning they were mature animals approaching the end of their expected life spans-to a range of tests and challenges that are commonly accepted methods of measuring changes in short-term memory and neuro-motor skills," says James A. Joseph, Ph.D., Chief, Neurosciences Laboratory, USDA Human Nutrition Research Center on Aging and lead researcher in the study. "Concord grape juice appeared to reduce or reverse the loss of sensitivity of muscarinic receptors, thus enhancing cognitive and some motor skills in the test animals. In many of the tests we saw significant improvements or trends toward improvement."
The memory test was the Morris water maze, an age-sensitive challenge that requires animals to use spatial learning to find a platform submerged 2 cm below the surface of a pool of water. Rats fed a 10% solution of Concord grape juice found the platform in roughly 20% less time than the control group. Other tests measured the animals' ability to balance on a horizontal stationary rod; a rotating, slowly accelerating rod; and various sized planks, and their ability to hold onto a suspended wire and an inclined wire screen. Some of those tests saw improvements in either or both of the group consuming a 10% solution of Concord grape juice and the group consuming a 50% solution.
"The Concord grape juice findings are not surprising," explains Joseph. "We have seen similar effects in the work we've done in blueberries."
The researchers point to several factors as potential mechanisms of action, including increased dopamine production and a potent overall antioxidant effect. According to previously published USDA studies, Concord grape juice has the highest total antioxidants of any fruits, vegetables or juices tested.
"As our population ages, we are continually looking for ways to maintain our mental and physical skills," notes Joseph. "While these laboratory animal studies are certainly preliminary and much more work needs to be done, we know that consuming high levels of natural dietary antioxidants is a good thing from a number of perspectives. And it appears that drinking Concord grape juice has the potential to help retard the mental and physical declines of aging."
The study was funded by the USDA Agricultural Research Service, the Michigan Department of Agriculture and a grant from Welch Foods, Inc.