"Using this rigorous approach, we found few consistent differences between ecstasy users and non-users on wide-ranging measures of verbal and visuospatial memory, verbal fluency, attention, processing speed, manipulative dexterity and executive cortical functions. Ecstasy users exhibited lower vocabulary scores than non-users, but this finding probably indicates differences in pre-morbid ability rather than neurotoxicity of ecstasy, as vocabulary is generally preserved even after neurological insults [26,45,46]. Indeed, assuming that these differences in pre-morbid verbal ability are valid, the absence of significant differences on most other tests, including tests of verbal memory, becomes even more striking. Although we found a few other significant differences between the overall groups of users and non-users, these differences proved to be concentrated primarily in moderate users, rather than heavy users—suggesting that they were unlikely due to neurotoxicity of ecstasy. More likely, such differences represent chance associations—a phenomenon to be fully expected, given that we performed multiple comparisons without formal statistical correction."

Source

Halpern, John H.; Sherwood, Andrea R.; Hudson, James I.; Gruber, Staci; Kozin, David; Pope Jr, Harrison G., "Residual neurocognitive features of long-term ecstasy users with minimal exposure to other drugs," Addiction Research Report (London, United Kingdom: Society for the Study of Addiction, April 2011), Volume 166, Issue 4, p. 783.
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