Chronic MDMA use is linked to memory and thinking problems, but past research often failed to separate effects of MDMA from those of other drugs like stimulants. In this study, 26 MDMA users who avoided stimulants, 25 MDMA users who also used stimulants, and 56 non-users completed cognitive tests. Hair analysis confirmed drug use patterns. MDMA-only users showed strong, specific impairments in declarative memory (effect size d=0.90), while stimulant-using MDMA users had broader, larger deficits across memory, working memory, executive functions, and attention (d=0.70 to 1.21). The findings suggest that pure MDMA use mainly harms declarative memory, whereas additional cognitive deficits stem from stimulant co-use.
Regular recreational use of MDMA (Ecstasy) is linked to verbal memory problems, and this study examined the brain changes underlying these deficits. Comparing 61 MDMA users with 61 matched non-users, the researchers found reduced grey matter volume in hippocampal regions and impaired verbal learning, short-term recall after interference, long-term recall, and recognition in users. Self-reported MDMA use over the past six months correlated with several memory scores. Hippocampal volume, especially in the CA1 subregion, was inversely related to verbal long-term memory and to MDMA use intensity measured by hair concentrations. Differences in grey matter between groups correlated with brain serotonin receptor densities, suggesting a serotonergic basis for the structural and memory changes.