Students who regularly mix ecstasy with cannabis could expose themselves to an unforeseen risk: poor academic results.
The real toll of using these recreational drugs may not show up in brain scans but in students' grades, according to a Spanish study.
"What does it mean to you in your life to consume these drugs? This is the important message to deliver," Rafael de la Torre, the leader of the study, told The Times Higher .
Dr de la Torre's team at the pharmacology unit of the Municipal Institute for Medical Research in Barcelona, Spain, followed 120 ecstasy and cannabis users over three years as they went through university.
The preliminary results suggest that drug users attained half the marks of students in a control group who did not take drugs.
Ecstasy has been demonised as a brain-crippling drug. Yet the scientific community remains divided about its impact: while few endorse the idea that the drug is harmless, there is no consensus on how dangerous it really is.
Ecstasy is taken by an estimated 8 million people world-wide. Clubbers love it because it floods their brain with the mood-enhancing compound serotonin. The surge in serotonin induces a feeling of euphoria. But this feel-good experience comes at a price because ecstasy use has been shown to affect long-term memory.
Brain imaging data from previous research suggested that people who stick to ecstasy alone have worse memory problems than those who combine it with cannabis or other drugs.
Users were asked to perform short-term memory tests while inside a brain scanner - researchers found that the activation patterns in the hippocampus areas of the brain were altered to greater extent in those using pure ecstasy compared with polydrug users.
Other researchers have found that people who use ecstasy and cannabis combined report higher positive moods and greater wellbeing than those who take ecstasy by itself.
The explanation for this counterintuitive finding could be that cannabis has an antioxidant effect, taking up the neurotoxic free radicals that are generated by ecstasy.
Dr de la Torre's said that the combination of ecstasy and cannabis could affect users for the rest of their lives. Speaking at a Novartis Foundation meeting in London, he stressed that for a young person, the prospect of failing to make the grade could act as the strongest deterrent.