Risk Taking and the Adolescent Reward System: A Potential Common Link to Substance Abuse

Objective: Increased risk-taking behavior has been associated with addiction, a disorder also linked to abnormalities in reward processing. Specifically, an attenuated response of reward-related areas (e.g., the ventral striatum) to non-drug reward cues has been reported in addiction. One unanswered question is whether risk-taking preference is associated with striatal reward processing in the absence of substance abuse. Method: Functional and structural MRI was performed in 266 healthy young adolescents and in 31 adolescents reporting potentially problematic substance use. Activation during reward anticipation (using the monetary incentive delay task) and to gray matter density were measured. Risk-taking bias was assessed by the Cambridge Gamble Task. Results: With increasing risk-taking bias, the ventral striatum showed decreased activation bilaterally during reward anticipation. Voxel-based morphometry showed that greater risk-taking bias was also associated with and partially mediated by lower gray matter density in the same structure. The decreased activation was also observed when participants with virtually any substance use were excluded. The group with potentially problematic substance use showed greater risk taking as well as lower striatal activation relative to matched comparison subjects from the main sample. Conclusions: Risk taking and functional and structural properties of the reward system in adolescents are strongly linked prior to a possible onset of substance abuse, emphasizing their potential role in the predisposition to drug abuse.