In a sample of 49 polysubstance users in residential treatment who had been abstinent for a prolonged period, the severity of use of heroin, alcohol, MDMA, and cannabis each showed negative correlations with brain metabolism in the dorsolateral prefrontal cortex and temporal cortex. Alcohol use was additionally linked to lower metabolism in the frontal premotor cortex and putamen, while stimulant use was associated with lower metabolism in the parietal cortex. These findings suggest that different drugs of abuse may produce overlapping and distinct patterns of brain dysfunction even after extended abstinence, which could inform targeted rehabilitation strategies.
Recreational ecstasy use, often alongside cannabis, is linked to lasting cognitive deficits. Over two years, regular ecstasy users performed worse than cannabis-only users and non-users on tests of verbal fluency, working memory, and processing speed. Heavier users (more than 100 tablets) also showed impairments in episodic memory. These deficits persisted across the study period. The findings suggest that ecstasy, possibly combined with cannabis, causes subtle but lasting cognitive harm, though pre-existing differences between groups cannot be ruled out.
Chronic methamphetamine users show diminished cognitive and emotional empathy toward positive stimuli, elevated punitive social behavior regardless of provocation, and heightened self-reported trait anger compared to non-users. Chronic MDMA users differ from controls only by displaying increased punitive behavior when provoked. Higher hair concentrations of both drugs may be linked to reduced cognitive empathy, and greater lifetime MDMA use correlates with more punitive behavior among MDMA users. The dopaminergic mechanism of methamphetamine may underlie social-cognitive deficits.