Web edition: July 26, 2012
Print edition: September 8, 2012; Vol.182 #5 (p. 13)
Light use of the club drug Ecstasy may cause subtle memory deficits. People who popped just three Ecstasy tablets a month over the course of a year saw their memory slip on a laboratory test, scientists report online July 25 in Addiction.
The new results offer some of the best evidence yet that the drug can change the brain, says psychiatric neuroscientist Ronald Cowan of Vanderbilt University Medical Center in Nashville. “It’s been very, very difficult to convince people that there’s a causative effect of the drug,” he says. “This adds strong evidence to that.”
Scientists debate whether Ecstasy, a drug that brings euphoria, boundless energy and heightened sensory experiences, can actually harm the brain in part by screwing with cells that produce the chemical messenger serotonin. Past studies have been notoriously hard to interpret because brain differences seen between Ecstasy users and nonusers could have existed long before the drug use began. And people who use Ecstasy frequently tend to use other drugs too, making it hard to tease out Ecstasy’s effect.
For the study, Daniel Wagner of the University of Cologne in Germany and his colleagues wanted to catch people as they started using Ecstasy. The team recruited 149 people who had used Ecstasy five or fewer times and ran the subjects through a battery of brain tests looking for signs of mental deficits. One year later, the team retested 43 people who had not used Ecstasy since being recruited, and 23 who had used 10 or more Ecstasy pills in that time. These people reported using an average of 33.6 tablets.
On most laboratory tests, the two groups performed similarly. But on one memory test, participants who had used Ecstasy scored worse. Ecstasy users had trouble remembering which distinctive border had framed a particular picture, both immediately after they saw a set of images and one hour later. The results show that a moderate amount of Ecstasy use over just a year can cause memory problems, says Wagner. “We were really surprised by that.”
It’s not clear whether this deficit picked up in the laboratory would be noticeable in everyday life, says neuroscientist Jerrold Meyer of the University of Massachusetts Amherst. Perhaps some populations, such as students, would suffer more consequences from this particular memory problem, he says.
“I’m reasonably convinced by their data, but obviously as with any study, there are always unanswered questions,” Meyer says. Scientists don’t know if memory skills would bounce back when Ecstasy use stopped, for instance, or whether the severity of the memory problem scales with the amount of Ecstasy used.
Larger studies that examine loads of different aspects of mental function may help address these uncertainties. “To have a comprehensive answer, you need to study a drug from many different domains,” Wagner says. For now, “it’s hard to say that it’s a harmful drug.”
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