Columbus, Ohio -- A new study in rats suggests that aging by itself may not affect brain systems responsible for important aspects of learning and memory. However, the research found that the combination of old age and pre-existing brain pathology led to serious problems in a brain system that is crucial for normal cognitive abilities.
The findings have important implications for researchers studying Alzheimer's disease and other forms of dementia in humans, said Martin Sarter, co-author of the study and a professor of psychology at Ohio State University.
"The aging of the brain may not be sufficient to produce seriously detrimental effects in humans," Sarter said. "It may be that only people who have a problem in important brain systems who will suffer dementia as they get older."
Sarter conducted the study with John Bruno, also a professor of psychology at Ohio State, and James Fadel, a former graduate student. Sarter presented their results June 6 in Denver, Colo. at the annual meeting of the American Psychological Society. The study was also published in the May 1999 issue of the journal Neuroscience.
In the study, the researchers trained rats to associate darkness with the appearance of food they liked. They did this because darkness would then stimulate the cholinergic system -- the brain system that involves memory functions and is associated with Alzheimer's disease and other forms of dementia. In order to further stimulate the cholinergic system, rats also received a drug to allow this system to react more readily to stimulation.
To measure the reaction of the rats' cholinergic systems to the stimulus of darkness and food, the researchers examined the release of acetylcholine (ACh), the crucial brain chemical that works within this system.
The researchers examined both young adult rats (four to seven months old) and
old adults (24 to 28 months old). In addition, some rats had brain lesions that
had destroyed some of the neurons in the
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Contact: Martin Sarter
Sarter.2@osu.edu
614-292-1751
Ohio State University
6-Jun-1999