Brain activity associated with social exclusion overlaps with drug-related frontal-striatal circuitry in cocaine users: A pilot study

BACKGROUND: Exposure to various types of stress can elevate craving for cocaine and hasten relapse among substance dependent individuals. This investigation evaluated the effects of social exclusion on brain activity in cocaine dependent individuals. METHOD: Forty three individuals (18 crack-cocaine users, 25 controls) were recruited from the community to participate in functional neuroimaging study in which they performed a simulated 3 person ball-tossing game (Cyberball). Each participant was told that the other 2 players were in nearby MRI scanners. Task blocks included: Inclusion (likelihood of our participant receiving the ball = 50%), Exclusion (likelihood gradually decreases to 0%), and Rest. Self-worth variables (e.g self-esteem, locus of control) were measured before and after the ball-tossing game. General linear model-based statistics were used to measure the brain response to inclusion and exclusion within and between the groups with respect to rest. RESULTS: Relative to controls, cocaine users had significantly more activity during Exclusion versus Inclusion in 3 areas: the right medial frontal gyrus (Brodmann Area 9,10), left ventral lateral frontal gyrus (Brodmann Area 10,47) and right caudate. This was driven by a higher response to social exclusion in the cocaine users. There was no difference between groups in the brain reactivity to social inclusion. CONCLUSION: Cocaine dependent individuals have an amplified brain response to social exclusion stress in cortical regions associated with emotional regulation, arousal, craving and perception of physical pain. These data suggest that there may be a neurological basis for the well-established relationship between social stress and addiction.