The differential effects of MDMA (ecstasy) use on executive and memory processes
The purpose of this thesis was to examine the nature of executive function deficits in ecstasy users, and the contribution of these executive functions to performance on other cognitive tasks. Using recent theoretical models of executive functioning recreational ecstasy-polydrug users were tested in laboratory settings on measures of mental set switching, response inhibition, memory updating and access to semantic memory. It was found that ecstasy users performed significantly worse than nonusers on measures of updating and access, although cocaine also emerged as an important factor in deficits in access. The contribution of access and updating to performance on more complex executive function tasks was then assessedI.t was found that while associative learning is relatively independent of access and updating, the same was not true for everyday memory and syllogistic reasoning. Ecstasy group related deficits in syllogistic reasoning were slightly attenuated following control for access and substantially following control for updating. It emerged that everyday memory deficits were more related to the use of cannabis than the use of ecstasy. The results of this thesis have serious implications for those who use ecstasy and should be used in educating such individuals. Outside the area of Psychopharmacology this thesis provides further support for the nature of executive functions and their relationship with syllogistic reasoning and everyday memory. Future research should assess executive functions along the same paradigm and seek to recruit polydrug control groups.