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"The serotonin system, which is compromised by MDMA, is fundamental to the brain's integration of information and emotion," says Dr. Alan I. Leshner, director of the National Institute on Drug Abuse (NIDA), National Institutes of Health, which funded the research. "At the very least, people who take MDMA, even just a few times, are risking long-term, perhaps permanent, problems with learning and memory."
The researchers found that the nerve cells (neurons) damaged by MDMA are those that use the chemical serotonin to communicate with other neurons. The Hopkins team had also previously conducted brain imaging research in human MDMA users, in collaboration with the National Institute of Mental Health, which showed extensive damage to serotonin neurons.
MDMA (3,4-methylenedioxymethamphetamine) has a stimulant effect, causing similar euphoria and increased alertness as cocaine and amphetamine. It also causes mescaline-like psychedelic effects. First used in the 1980s, MDMA is often taken at large, all-night "rave" parties.
In this new study, the Hopkins researchers administered either MDMA or salt water to the monkeys twice a day for 4 days. After 2 weeks, the scientists examined the brains of half of the monkeys. Then, after 6 to 7 years, the brains of the remaining monkeys were examined, along with age-matched controls.
In the brains of the monkeys examined soon after the 2-week period, Dr. George Ricaurte and his colleagues found that MDMA caused more damage to serotonin neurons in some parts of the brain than in others. Areas particularly affected were the neocortex (the outer part of the brain where conscious thought occurs) and the hippocampus (which plays a key role in forming long-term memories).
This damage was also apparent, although to a lesser extent, in the brains of monkeys who had received MDMA during the same 2-week period but who had received no MDMA for 6 to 7 years. In contrast, no damage was noticeable in the brains of those who had received salt water.
"Some recovery of serotonin neurons was apparent in the brains of the monkeys given MDMA 6 to 7 years previously," says Dr. Ricaurte, "but this recovery occurred only in certain regions, and was not always complete. Other brain regions showed no evidence of recovery whatsoever."
Other authors of the study are Dr. George Hatzidimitriou and Dr. Una McCann.
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