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---------------------------------------------------------------------- Drug Boosts Working Memory ---------------------------------------------------------------------- NEW YORK (Reuters) -- Scientists seeking to unravel the neurochemistry of short-term, or working, memory have found that the neurotransmitter dopamine may play an important role. This knowledge may lead to the development of drugs to improve memory in patients with neurological impairment, such as brain injury. In fact, study results reported in the journal NeuroReport demonstrate for the first time that the dopamine-like drug bromocriptine can improve memory performance. The drug is sometimes given to people with Parkinson's disease. But the researchers caution that the drug does not necessarily aid memory in healthy people -- their findings suggest that adding more dopamine to normal levels in the brain can worsen performance on memory tests. "Certainly at this stage and probably for the foreseeable future and beyond, there is no actual benefit (for healthy people) from taking bromocriptine," says study co-author Dr. Daniel Kimberg, a postdoctoral research fellow in neurology and psychology at the University of Pennsylvania Medical Center in Philadelphia. "Basically, we were interested in finding out how the neurotransmitter dopamine interacts with working memory in healthy, non-brain-injured individuals." He points out that bromocriptine was used in the study because "it is a safe drug to use with human subjects." Kimberg and his colleagues used the lowest dose of bromocriptine to reduce the risk of adverse side effects. They recruited 31 healthy volunteers, who received either a placebo (inactive pill) or 2.5 milligrams of bromocriptine prior to taking a series of nine cognitive tasks focusing on working memory, such as memory for the location of dots on a computer screen. In addition, subjects performed "higher level cognitive tasks" of brain frontal lobe functioning such as a sorting test in which cards are matched according to color, shape, or number. The researchers noticed that subjects whose baseline scores were better than average on a test of working memory did worse when tested again a few hours after taking bromocriptine. "And others who scored below the mean (average) tended to get better after taking the drug," Kimberg says. "At a certain neurochemical level, this suggests there's an optimal 'tuning' level of dopamine for short-term, or working memory to function properly," the researcher adds. "Adding more dopamine when memory capacity is already at a higher level seems to impair rather than improve performance." According to senior author Dr. Mark D'Esposito, assistant professor of neurology, the study was repeated in people with damage in the frontal lobes of their brains. He says scores on the same memory tests improved in these individuals, thus indicating there may actually be some clinical applications of the drug in brain-injured people. SOURCE: NeuroReport (1997;8:3581-3585) 1997, Reuters Health eLine <http://www.medscape.com/reuters/mon/t1126-2f.html> ---------------------------------------------------------------------- janet [log in to unmask]