George Ricaurte. Ricaurte was a relatively young and inexperienced researcher, but his work has been very predictable: Every time the government gives him money, he came back with an 'anti-drug' research article to support their claims. (Indeed, it's about the only sort of research Ricaurte seems to have ever done.)

'Ecstasy' and Memory

Once upon a time, a study of 'ecstasy' user's cognitive function (how mentally sharp they were) came out. It found that, compared to non-users, the 'ecstasy' users had slightly worse memory in some areas (mainly word recall.)[6]

The government of course hailed this as proof that the demon-drug ecstasy was destroying poor young minds. However, the study was far less clear-cut than it first appeared. The author (Ricaurte) failed to control for disruptions of sleep patterns (long known to affect cognitive function, and likely to be an issue among stimulant users.) His 'non-users' were also younger, better educated, and had higher vocabulary scores than his 'ecstasy user' group. The 'ecstasy' users also took considerably more of all sorts of drugs than the non-ecstasy users did. They used more opiates, they used more amphetamines...and they smoked considerably more pot, long known to cause (non-permanent) memory problems. Indeed, there were numerous possible explanations for the modest differences in memory, including neuroadaptive responses to recent MDMA exposure.

Marijuana in particular has proven to be a major factor is such test scores. In one study from the Australian government, it was found that, although people who used 'ecstasy' and pot did have slightly worse memories than people who didn't use any drugs, the deficits were in the same places and of the same magnitude as those seen in the group of people that used similar amounts of pot but no 'ecstasy'. The 'ecstasy' users didn't have poor memories because they were ecstasy users: They had slightly poorer memories because they were unrepentant potheads. [7]

(It should be noted that minor memory problems in the days after use are common, due to disruption of the serotonin system and fatigue. Heavy users also often show some memory and concentration problems, similarly to marijuana (and even alcohol) users. This phenomenon appears to be the result of adaptive changes to the brain, not neurotoxicity.)