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den Hollander B, Schouw M, Groot P, Huisman H, Caan M, Barkhof F, Reneman L. 
“Preliminary evidence of hippocampal damage in chronic users of ecstasy”. 
J Neurol Neurosurg Psychiatry. 2011 Mar 29.
Various studies have shown that ecstasy 3,4-methylenedioxymethamphetamine users display significant memory impairments, whereas their performance on other cognitive tests is generally normal. The hippocampus plays an essential role in short-term memory. There are, however, no structural human data on the effects of ecstasy on the hippocampus. The objective of this study was to investigate whether the hippocampal volume of chronic ecstasy users is reduced when compared with healthy polydrug-using controls, as an indicator of hippocampal damage. The hippocampus was manually outlined in volumetric MRI scans in 10 male ecstasy users mean age 25.4 years and seven healthy age- and gender-matched control subjects 21.3 years. Other than the use of ecstasy, there were no statistically significant differences between both groups in exposure to other drugs of abuse and alcohol. The ecstasy users were on average drug-free for more than 2 months and had used on average 281 tablets over the past six and a half years. The hippocampal volume in the ecstasy using group was on average 10.5% smaller than the hippocampal volume in the control group (p=0.032). These data provide preliminary evidence that ecstasy users may be prone to incurring hippocampal damage, in line with previous reports of acute hippocampal sclerosis and subsequent atrophy in chronic users of this drug.
Comments and Responses to this Article
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Apr 17, 2011 18:23
MAPS : Ilsa Jerome's Review of Article #

See MAPS : Ilsa Jerome's Comments and Review.

"These findings have few implications for use of MDMA in clinical research studies, given the minimum reported lifetime exposure of 50 tablets, and given that ecstasy is a product that varies in content and purity."
Status: display
Apr 17, 2011 18:43
Study has a Low N and Overstates Similarity of Groups #

This is based on a group comparison of 10 users to 7 controls. The users had a greater level of reported use for every single drug measured -- ecstasy, alcohol, tobacco, cannabis, cocaine, and amphetamine -- which could account for any group differences in brain imaging. Groups were 'matched' on drug use, meaning they weren't found to be statistically different, but this can be misleading. Although it is common to use the lack of statistical significance to assure that groups are matched, it adds little assurance of matching when it comes to small-sample between-group designs like this, where even large differences may fail to be statistically detected due to low power. For example, you could have a mean age difference of 20 years between groups but fail to detect it statistically; this does nothing to rule out age as a confound. It's more appropriate to compare actual values for means/medians or effect sizes rather than inferential stats when matching such small samples. Magnifying this concern, they used a chi-square (categorical, non-parametric) test to assess differences in level of drug use across groups, where you'd have more power to find differences if you used the actual quantitative data (e.g. t-test). They were virtually guaranteed to find no significant differences between groups regarding drug use with this approach. This, combined with the possibility that self-selection or an un-assessed alternative variable could drive the hippocampal differences in such a small group design, pretty much precludes causal conclusions from the study regarding ecstasy.
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Apr 17, 2011 18:44
Web MD Copies Findings into Press Release #

Web MD's "Study Shows Chronic Ecstasy Users Have Reduced Volume of Hippocampus Region of Brain"

"Long-term users of the street drug ecstasy may be at increased risk of structural brain damage, new research suggests.

Researchers in the Netherlands enlisted 10 men in their mid-20s and seven in their early 20s for the study. The 10 in the mid-20s were long-term users of ecstasy. The other seven men were healthy and had no history of ecstasy use."

WebMD at least points out that the ecstasy users "had used more amphetamine and cocaine than the non-ecstasy group" (unlike Science Daily), they drop the ball when they repeat the authors' erroneous assertion that the "groups had used similar amounts of recreational drugs".

WebMD also drops the ball allowing the use of the word "significant" in ambiguous contexts, such as this quote:
“Since the hippocampus plays an essential role in long-term memory, the present findings are of particular interest in view of the [previous] various studies showing that ecstasy users display significant memory impairments, whereas their performance on other cognitive tests is generally normal,” the researchers conclude.

The normal reader is left with little idea that the use of the word "significant" here is the should-be-banned-from-the-language technical meaning of "probably non-random", rather than the natural English meaning of "important" or "large".

WebMD also makes the error of restating the authors' speculation without caveat that their findings, which were limited to the hippocampus in a small number of people, might mean bad things for the rest of the brain as well. "The researchers say this suggests that the effects of ecstasy may not be restricted to the hippocampus region alone."
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Apr 17, 2011 18:24
Science Daily Regurgitates Findings Uncritically #

Science Daily Reports Findings. Most media sources reporting on science related to recreational psychoactives just regurgitate the findings as stated in the abstract with some additional scary comments by the authors. This Science Daily article is no different. They provide no critical viewpoint and even restate the false premise from the paper that the two groups were well matched for other drug use, they were not. Science reporting is, overall, crap.
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Apr 17, 2011 3:14
Medscape Coverage # Medscape regurgitation of abstract with some actual commentary, but still uncritical, no indication that the finding might NOT indicate a causal linkage.
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