A drug currently used to lessen the effects of Alzheimer’s disease may soon be able to aid healthy adults in perceptual learning, according to a study by U. California-Berkeley researchers.
In the study, published Sept. 16 in the science journal Current Biology, UC Berkeley researchers Michael Silver and Ariel Rokem found a link between the use of the Alzheimer’s drug donepezil and improved attention and memory in adults not affected by the disease while the subjects performed a specific task.
Donepezil, a drug often prescribed to Alzheimer’s patients, raises the level of one of the brain’s signaling molecules – called acetylcholine – by destroying the enzyme that inhibits its longevity.
“Acetylcholine is involved in many different processes in the brain including voluntarily devoting focused attention to a particular portion of the visual field when you know something important might appear in that location,” Rokem, a postdoctoral fellow at the campus Helen Wills Neuroscience Institute and lead author of the study, said in an e-mail.
Twelve subjects participated in the study, which had them take a 5-milligram dose of the drug during the first round of five-day courses and a placebo during the second round about two weeks later.
After each round of courses, the subjects took a test that measured perceptual learning by reporting whether two sequentially presented fields of moving dots were proceeding in the same direction.
“Perceptual learning is the ability to get better at a particular perceptual discrimination with practice,” Silver, an assistant professor at the School of Optometry and the Helen Wills Neuroscience Institute and the study’s principle investigator, said in an e-mail. “With practice, anyone can improve their ability for a given perceptual discrimination, but in our experiments, subjects taking donepezil during practice show about twice as much improvement in perceptual ability compared to subjects practicing under placebo.”
Silver noted that the study only revealed an improvement in attention in the specific task that the subjects were given, and more research is needed to determine whether the drug would enhance performance in other tasks.
“One analogy is a fruit inspector who becomes very good at discriminating small differences in the colors of red apples,” Silver said in the e-mail. “This perceptual learning for color discrimination of red may not generalize to discriminating colors of green apples.”
Ahmad Salehi, a clinical associate professor of psychiatry and behavioral sciences at Stanford University, said in an e-mail that the study is immensely important in helping researchers understand the role acetylcholine plays in the cognitive processes of both healthy people and people with the disease.
Although the effects of donepezil are very beneficial to specific tasks involving visual perception, Silver notes that “it is far too early to say how donepezil may be used in the general population in the future.”
According to Aaron Seitz, UC Riverside assistant professor of psychology, this is the first study to make a direct link between acetylcholine and visual perceptual learning in humans.
“This research shows promise,” he said in an e-mail. “With more detailed studies, acetylcholine can be used to help optimize learning procedures to produce better and greater learning effects in people with sensory and learning disabilities as well as in the general populations.”