Data suggest that MDMA may be toxic to the brain. Dr. George Ricaurte, an associate professor of neurology at Johns Hopkins University, analyzed brain scans of people who had used ecstasy. The study included people who had used ecstasy an average of 200 times over five years. Although the behavior of these people appeared normal, brain scans showed that the drug had damaged their brains. In fact, those who used the drug more often had more brain damage than less frequent users. Moreover, memory tests of people who have taken ecstasy as compared to non-drug users have shown that the ecstasy users had lower scores. Specifically, the drug damaged cells that release the neurotransmitter called serotonin. Using an imaging technique called positron emission tomography (PET), Ricaurte noted a 20-60% reduction in healthy serotonin cells in the drug users. Damage to these cells could affect a person's abilities to remember and to learn.
At this point, scientists do not know if this damage is permanent, or if those damaged cells will replace themselves. Also, it is not known if this loss of cells affects behavior or the ability to think. Ricaurte is conducting other studies to gauge ecstasy's effect on mood, memory, cognition, and behaviors such as eating and sleeping. In 2003,
German researchers used PET scans to study the brains of current and past users of ecstasy. This research demonstrated that ecstasy users had lower levels of serotonin activity in several brain areas. However, ecstasy users who stopped using the drug 20 weeks before the scan showed some recovery in serotonin function.