A prospective cohort study followed 109 nearly MDMA-naive subjects for 12 months to determine whether cognitive deficits appear after beginning MDMA use. Twenty-three subjects who used more than 10 MDMA pills (mean 33.6 pills) were compared with 43 subjects who used no illicit drugs besides cannabis. Groups did not differ in age, intelligence, cannabis, alcohol, or other lifestyle confounders. MDMA users showed significant impairments in immediate and delayed recall of a visual paired associates learning task compared with controls, but no differences emerged on other tests of memory, learning, or executive function. The findings suggest MDMA specifically impairs visual paired associates learning, possibly due to serotonergic dysfunction in the hippocampus.
Cannabis-dependent men show exaggerated cognitive performance deterioration during psychosocial stress compared to controls, despite reporting similar stress levels and cardiovascular responses. Brain imaging revealed that this performance decline was accompanied by reduced activity in the precuneus and increased connectivity between the precuneus and the superior frontal gyrus during stress exposure. The findings provide first evidence linking chronic cannabis use to altered neural stress processing, specifically deficient recruitment of the precuneus, which may underlie stress-induced cognitive impairments in cannabis users.