IT CAME as a bombshell last September when researchers announced that a single night on the drug ecstasy might cause brain damage and symptoms of Parkinson鈥檚 disease. The warning, based on primate research published in Science, struck fear into anyone who had taken the 鈥渓ove drug鈥�. Had they condemned themselves to a progressive, debilitating disease?
But it was all a ghastly mistake. A retraction this week in Science makes clear that an erroneous label on a bottle meant that the 10 squirrel monkeys and baboons in the original experiment were not given ecstasy, but methamphetamine. It was an all too human mistake, yet its implications have been huge.
Ecstasy was known to affect serotonin pathways in the brain, but here was evidence that it also damaged the same dopamine-producing cells that die in Parkinson鈥檚 disease. The study鈥檚 findings strengthened the hand of anti-drugs campaigners and fuelled argument over a proposed US law to punish club owners who turned a blind eye to drugs.
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Yet many scientists viewed the results with disbelief. They questioned whether the animals鈥� doses were equivalent to what a person would take in a night. Two animals died after their injections and two others were so distressed they had to be withdrawn from the study. If humans responded like this, they would be dropping like flies on the dance floor. And if ecstasy increased susceptibility to Parkinson鈥檚, where were the human casualties?
The researchers, led by George Ricaurte of Johns Hopkins University, Baltimore, defended their results in the letters pages of Science, finding reasons why criticisms of their work were misplaced. How did things get this far?
Extraordinary claims need extraordinary evidence: surely the idea that a widely used drug might cause brain damage demanded a systematic check of every aspect of the study? Apparently not. And what happened at Science? Leading neuroscientists criticised the work as soon as it was published, suggesting that peer review had been cursory at best.
We should also ask whether a leading journal would have been so eager to publish if the findings had suggested ecstasy鈥檚 impact on the brain was smaller than expected. In the past, researchers with such evidence have found high-status journals reluctant to accept their work.
It is a fact that ecstasy鈥檚 impact on the brain and behaviour are subtle, and studies often find contradictory results. Some brain-scanning techniques and other ways for gauging its effects are in their infancy. Unless researchers acknowledge these uncertainties in their papers, they risk misleading the public and damaging the credibility of science.
Governments and anti-drugs campaigners tend to trumpet findings that show illicit drugs in a bad light, and ignore criticism of that work. But science should not be party to this. Young people know that millions have taken ecstasy without obvious harm. They have great 鈥渉ype antennas鈥�. If scientists tell them something that does not match their own experience, they will question its credibility and have the perfect excuse to ignore any future warnings.