Objective
Attention-deficit/hyperactivity disorder (ADHD) is a heritable neuropsychiatric disorder associated with abnormal reward processing. Limited and inconsistent data exist about the neural mechanisms underlying this abnormality. Furthermore, it is unknown whether reward processing is abnormal in unaffected siblings of participants with ADHD.
Method
We used event-related functional magnetic resonance imaging (fMRI) to investigate brain responses during reward anticipation and receipt with an adapted monetary incentive delay task in a large sample of adolescents and young adults with ADHD (n=150), their unaffected siblings (n=92), and control participants (n=108), all of the same age.
Results
Participants with ADHD showed, relative to control participants, increased responses in the anterior cingulate, anterior frontal cortex, and cerebellum during reward anticipation, and in the orbitofrontal, occipital cortex, and ventral striatum during reward receipt. Responses of unaffected siblings were increased in these regions as well, except for the cerebellum during anticipation and the orbitofrontal cortex during receipt.
Conclusion
ADHD in adolescents and young adults is associated with enhanced neural responses in frontostriatal circuitry to anticipation and receipt of reward. The findings support models emphasizing aberrant reward processing in ADHD and suggest that processing of reward is subject to familial influences. Future studies using standard monetary incentive delay task parameters have to replicate our findings.