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1999 Morgan MDMA Memory Study
A Review
by Erowid
Memory Deficits associated with recreational use of ecstasy (MDMA),
by M.J. Morgan
Psychopharmacology Vol 141, 1999, 30-36




What Morgan and the researchers find is that MDMA use is strongly correlated with reduced memory scores.

I have a couple of comments on this study, some of which are general comments about the state of the MDMA-long term consequences / memory deficit question.

  1. Size of study. As with other studies, the populations being studied are very small. The total number of MDMA users in this study was 25. Given that several studies have now demonstrated the possibility of medium or long term memory disruption in regular MDMA users, it seems most important that a study involving hundreds of MDMA users versus well matched controls should take place.

  2. Long-Term versus Medium-Term. Each of these terms is defined softly, but I define short term as the period after use between 1 and 30 days. Medium term might be defined as 4 weeks post use to perhaps 6 to 12 months with Long-Term defined as more than a year. I think this is an important distinction, especially in light of the apparent medium term effects of MDMA use (many users report feeling after effects for 4-6 weeks after their last use).

  3. Conflicting Data. In both this study and in the McCann memory study of 98 (link) there are some conflicting data. In this paper, the MDMA subgroup scores overall lower than the control group: Control Group scored 8.29 (Immediate Recall) and 7.61 (Delayed Recall) while the MDMA group scored 6.14 (IR) and 5.36 (DR). But the last figure in the paper (table 4) shows that the MDMA subgroup has significant variation in scores which may be correlated to time since last use, the 3 members of the MDMA subgroup that had not used MDMA for at least 6 months scored 9.0 (IR) and 9.0 (DR), which is significantly higher than the control group which had never used MDMA. What are we to think of this?

Table 4 : Means (SD) of number of ideas recalled for sub-groups of the MDMA group defined by period elapsed since last use of ecstasy

Period since last use: < 1 month 1-6months > 6 months
n per group 13 9 3
Immediate Recall 6.04 (2.18) 5.33 (1.87) 9.00 (1.32)
Delayed Recall 5.62 (2.31) 3.78 (1.33) 9.00 (1.80)

Table 3: Group means (standard deviations) of number of RMBT ideas recalled

  Non drug group Polydrug group MDMA group
n per group 19 22 25
Immediate Recall 8.29 (2.87) 8.09 (1.86) 6.14 (2.23)
Delayed Recall 7.61 (2.74) 7.23 (1.90) 5.36 (2.48)

In the McCann study, heavy MDMA use was correlated to increasing (bettering) scores on some tests, while correlating to reduced (worsening) scores on other tests. Without large sample sizes and broad tests, it seems difficult to know how to interpret the data.

Overall, this study is a good attempt to try to separate the possible confounding issues of poly drug use and MDMA use and is another good piece of data pointing towards possible medium/long term effects of MDMA use, but it is more of a road sign pointing ahead than it is a conclusion.