Raising new concerns about use of the popular recreational drug ecstasy, or MDMA, scientists have found that just a few doses of the substance causes extensive damage to brain cells in monkeys. The findings, published today in the journal Science, suggest that using ecstasy may increase the risk of developing Parkinsonism--a condition similar to Parkinson's disease--later in life.
Earlier animal studies had shown that repeated ecstasy use damages the serotonin brain cells, which help to regulate mood and behavior. In the new work, Johns Hopkins University researchers working with squirrel monkeys and baboons found that two or three sequential doses of the drug--the amount typically taken by young adults at all-night "raves"--killed dopamine neurons, which are involved in controlling movement, emotional and cognitive responses and the ability to feel pleasure. Indeed, some 60 to 80 percent of the dopaminergic nerve endings in a region of the brain known as the striatum were destroyed after just one multi-dose regimen. (In the image above, the depletion of dopamine binding sites is indicated by the increase in blues and greens seen in the scan on the right compared to the one on the left.)
In humans, once damage to these nerve endings crosses a certain threshold, leading to an 80 to 90 percent loss of brain dopamine, Parkinsonism typically occurs. If ecstasy damages dopamine neurons in humans the way it does in monkeys, team member George A. Ricaurte says, Parkinsonism could develop years after taking the drug because brain dopamine declines with age. "The message seems clear," he adds. "The neurotoxic potential of MDMA is high, and use of several sequential recreational doses could have serious, long-term consequences."