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1998 Parrott MDMA Cognition Study
A Review
by Erowid
Ecstasy (MDMA) effects upon mood and cognition: before, during and after a Saturday night dance,
by A.C. Parrott; J. Lasky
Psychopharmacology Vol 139, 1998, 261-268




Parrott's study is an interesting attempt to try to capture information about cognitive effects of MDMA in more real-world conditions.

Unfortunately the author's conclusions seem unwarranted based on the data they present. They claim that "Memory recall was also significantly impaired in drug-free MDMA users, with regular ecstasy users displaying the worst memory scores at every test session." and that "The cognitive deficits in drug-free recreational ecstasy users suggest that MDMA may also be neurotoxic in humans."

One problem with this and other studies which seek to 'confirm the damage done by MDMA' is that they seem to be willing to exaggerate the subtleties of the data and ignore any potentially conflicting data as long as some portion of it supports their thesis. Any medium & long term cognitive effects of MDMA are extremely important to those who use this chemical and it's important that the risks be properly assessed and not exaggerated.

In this study, each individual took the same memory test four times. Three times while not intoxicated and once while at a party most intoxicated, but some control subjects not intoxicated. The average memory scores of the regular MDMA users (while not intoxicated) are 12.0, 11.1, and 11.4. The average memory scores of the non-users were 15.1, 12.9, to 13.4. While the regular MDMA users do score lower than the non-users, there are several factors which make any generalizations of long term damage based on this data suspect:

  1. Reliability of test results:
    The variations in scores for the 3 "non intoxicated" tests for the controls subjects is over 2 points with the 15.1 standing out as a potentially aberrant value. If this test is reliable enough to base a guess about general population memory scores after MDMA use, it seems that a 15% (15.1 to 12.9) variation between test results for the exact same small group of individuals would indicate that a far larger number of tests would be necessary to say that the regular MDMA users 7% score difference from the control subjects (12.9 to 12.0) is reasonably called a "deficit" instead of a random occurance.

  2. Short vs Long term effects :
    If MDMA has some short term memory effects (from 1-45 days after each session) on users, then any statements about "long term deficits" would be unreliable unless the MDMA users were abstinent for a _minimum_ of 4 weeks before the tests. The researchers do not say for how long before the initial test the MDMA users were drug free and merely assert that their first test which they call their "baseline" is indicative of a "drug free" state. It seems quite possible that the MDMA users had used ecstasy within the previous two or three weeks and thus their scores would be indicative of short-term effects rather than long or even medium term effects. The confusion between short, medium, and long term effects is a problem with most of the research looking at cognitive and behavioural problems.

  3. Non Memory Tests:
    This study also gave a set of visual search tests which were successive grids of random letters on a newton palmtop where the subject was supposed to hit the letter "L" with their stylus. The time to hit the correct letter was their score. The controls scored much better on the simplest of these than the MDMA users during the "baseline" test before the party. As with the memory scores for this baseline test, the scores seem suspicious and bring the value of the data into question. The controls averaged a score of 1.2 seconds on their first attempt at the test and then 1.9 seconds 2 days after the party and then 2.7 seconds 7 days after the party. This is a dramatic variation in score: From 1.2 to 2.7 both tested in similar conditions. The regular MDMA users scored 1.8, 2.2, and 2.6 on this test. The 'regular MDMA users' average scores on two of the three non-intoxication tests were lower (better) than one of the three control tests. What this primarily seems to indicate is that the number of subjects or the method of test administration make it absurd to extrapolate from these tests to any conclusion.

Intoxication Effects:
One thing this study does is to include giving tests to the subjects while they are intoxicated on a variety of substances, including: MDMA, cannabis, cocaine, amphetamines, alcohol, and cigarettes. On a single evening at the club, the participants ingested the following: Alcohol was ingested by 10 of the 15 controls (averaging 5 drinks), 5 novice MDMA users (averaging 2.7 drinks) , and 6 regular users (averaging 3.7 drinks). Cannabis was smoked by 3 controls, one novice MDMA user, and two regular MDMA users. Cocaine was taken by two controls, two novice MDMA users, and four regular MDMA users. Only one novice MDMA user took another amphetamine.

When they gave these people the battery of tests, their scores were significantly lower than those from their non-intoxicated test sessions. This is, of course, no surprise at all, but mildly interesting nonetheless. They also gave the participants a set of mood related questions, to try to assess their state of mind, but the mood data doesn't really strike me as revealing anything unexpected or noteworthy.

The primary reason that many people take fun drugz is to give themselves a break from their daily stress. It should come as little surprise that interest or ability to focus attention on dull cognitive and memory tasks would be decreased. Perhaps what this part of the study tells us is that MDMA, alcohol, cocaine, and cannabis ingested together at a party may decrease one's ability to do linear thinking. Amusing.

Self reported side effects:
The final page of this study has some interesting comments by the MDMA-using subjects. The study itself did not concern itself with the anecdotal reports, but they may be the most compelling part of it. Parrott includes comments about previous experiences with serious negative effects, including hospital visits, collapsing on the dance floor, "occasionally crying for no real reason".

It would be interesting to see a study dedicated to primarily these self reports of problems and looking deeply into them and comparing them to well matched control groups, comparing the negative stories to those of alcohol users with similar frequences of use, etc.

Conclusion:
This study is one of those cited by news and other research as showing possible long term memory disruptions in regular MDMA users, but it seems like a very weak and preliminary piece of evidence. The variations of the test scores within each group, the fact that the researchers were most likely looking at short or medium term effects rather than long term effects, and the small size of the study together make this a not-very-compelling argument in favor of MDMA-related long term cognitive defects.