A controversial research paper suggesting that people taking the street drug Ecstasy for just one night might later develop Parkinson's disease has been retracted, after a labelling error was discovered on bottles used in the study.
Controversial ecstasy research used wrong drug
George Ricaurte and colleagues at Johns Hopkins University School of Medicine in Baltimore published their work in Science in September 2002, provoking widespread alarm in the media.
The team found that three consecutive doses of ecstasy, or methylenedioxymethamphetamine (MDMA), given to squirrel monkeys and baboons caused profound damage to dopamine-producing neurons in their brains. These are the neurons lost in Parkinson's disease.
The animals were injected with MDMA at three-hour intervals to mimic the way humans take the drug at all-night raves. Two of the 10 died within hours after developing hyperthermia.
But the group has issued a retraction in Science saying they discovered that all but one of the animals received amphetamines instead of the intended MDMA. Methamphetamine, also known as speed, would have been expected to produce these results, they say.
"We're very regretful about what it might have done, not only to our scientific colleagues, but to the public at large," Una McCann, one of the team, told The Baltimore Sun.
Startling findings"I'm surprised that senior researchers could make an error like that," says John Henry, a leading UK expert on ecstasy and illegal drugs at Imperial College London, UK.
He told New Scientist that the team should have checked their startling findings. "They should have known from the general background of their work that this was extremely unusual."
The team began to suspect a problem when many attempts to replicate their original findings failed. On investigating their lab records they found that the MDMA requested was delivered on the same day, by the same supplier, and in the same amount as a bottle of methamphetamine.
"When we began to suspect that the two bottles of drug might have borne incorrect labels, we requested that a sample of the drug in the bottle bearing '(+)-methamphetamine HCl' be analyzed by various analytical techniques," they write.
Three independent labs confirmed the bottle contained MDMA, not speed. The original bottle used by the team for the ecstasy experiments was empty, but analysis of the frozen brains of two animals that died during the study revealed they contained a metabolite of amphetamine.
Death rateThe bottles were sourced by the US National Institute of Drug Abuse (NIDA) in Bethesda and supplied by Research Triangle Institute International of North Carolina, a spokeswoman for NIDA confirmed.
However, the Johns Hopkins group stands by its claim that Ecstasy could have a grave impact on the dopamine system of the brain in humans. Evidence suggests Ecstasy may have a damaging effect on the serotonin circuits of the brain - an entirely different nerve circuit - but its effect on the dopamine system is controversial.
"I wasn't happy with the paper itself because they made the claim, and it was accepted by referees, that this was relevant to what humans were doing frequently," says Henry. "It's not relevant at all if one out of five died," because that death rate is not seen in people taking ecstasy.
However, Henry adds: "We have to applaud them for at least making a full and complete retraction."
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