The brain scans are unequivocal. For the first time, scientists have demonstrated that long-term users of the "rave drug" Ecstasy are permanently altering their brains. The tough question now is, are they actually damaging them?
Though the effects of the changes could take years or even decades to show up, it is potentially serious news for the UK's estimated 500,000 regular "E" users, who each take one or two tablets every weekend. If the brain cannot compensate for the changes caused by the drug, the long- term effects could include widespread depression and even suicide.
That is because Ecstasy affects the production of a chemical that modulates how happy we feel. In effect, repeated use might leave the brain drained of that chemical. But scientists are still debating whether, over time, our most adaptable organ might make allowances even for that change.
The latest research by George Ricaurte, assistant professor of neurology at Johns Hopkins University, used positron emission tomography (PET) scanners, which can produce detailed images of active areas of the brain, to study two groups, each of 14 recreational drugs users.
The first group used Ecstasy and other drugs; the others used drugs excluding Ecstasy. Though small, the number is sufficient to pinpoint differences between groups using PET.
Dr Ricaurte examined the peoples' brains to evaluate the activity of the millions of brain synapses which release a neurotransmitter called serotonin - the "happiness chemical". The control subjects had normal levels of serotonin activity. The Ecstasy users, though, showed deficiencies in all brain regions.
Una McCann, one of the team members, told New Scientist magazine that this is clear evidence that Ecstasy damages serotonin-generating synapses: "The message is that if you're going to use it, do it in moderation."
But David Concar, the deputy editor of New Scientist and a PhD in biochemistry, pointed out last night that the case against Ecstasy may not be so clear- cut. "The really tricky point about this is whether you call these changes `damage', or whether they are chemical responses to the drug which would in time reverse themselves." A scientist for the US Environmental Protection Agency commented that "there's no evidence of structural damage".
The knee-jerk reaction by drug opponents would be to point to this study as definitive evidence that Ecstasy does damage. Earlier studies using questionnaires have shown, though less convincingly than PET scans, that regular users of Ecstasy tend to be more depressed than non-users.
But that is not incontrovertible evidence of permanent damage. The human brain repeatedly demonstrates that it is capable of withstanding massive amounts of damage and rebuilding itself: people who have sufffered even serious strokes often regain many faculties, demonstrating that even real damage in which neurons actually die can be overcome.