Cannabis-dependent men performed worse on cognitive tasks under stress, linked to reduced precuneus brain activity

During stress but not during a no-stress condition, cannabis users showed impaired performance on mental arithmetic compared to controls. Subjective stress and cardiovascular responses were similar between groups. fMRI revealed that stress-induced performance decline in cannabis users was accompanied by decreased precuneus activity and increased connectivity between the precuneus and superior frontal gyrus.

fMRI study of 28 cannabis-dependent men and 23 matched controls using the Montreal Imaging Stress Task, which combines adaptive mental arithmetic with social evaluative threat. Behavioral performance, subjective stress, and cardiovascular responses measured alongside brain imaging.

Stress is a major trigger for cannabis relapse. Finding that cannabis dependence specifically impairs cognitive function under stress, with identifiable neural correlates, could help explain why stressful situations lead to both impaired function and relapse.

The dissociation between normal stress perception and impaired stress-related cognition suggests cannabis dependence disrupts how the brain translates stress into action, not how stress is experienced emotionally.

Only male participants studied. Cross-sectional design cannot determine if findings preceded or resulted from cannabis use. Cannabis-dependent participants were not acutely intoxicated, but residual effects cannot be fully excluded. Relatively small sample for fMRI.