Abstract
Objective: Attention-deficit/hyperactivity disorder (ADHD) has been linked to deficits in the dopaminergic reward-processing circuitry; yet, existing evidence is limited, and the influence of genetic variation affecting dopamine signaling remains unknown. We investigated striatal responsivity to rewards in ADHD combined type (ADHD-CT) using functional magnetic resonance imaging (fMRI), and whether it is modulated by variation in the dopamine transporter gene (DAT1).
Method: We tested 29 male adolescents with ADHD-CT and 30 age-, handedness-, and gender-matched healthy controls who were selected for DAT110/6 haplotype dosage. Based on previous research, we focused our analysis on the ventral striatum and the caudate nucleus.
Results: Three main findings emerged. First, male adolescents with ADHD-CT did not differ from controls in terms of blood oxygen–level dependent (BOLD) fMRI response to reward-predicting cues (gain or loss-avoidance) in the ventral striatum. Second, male adolescents with ADHD-CT showed a relative increase, compared with controls, in the striatal BOLD response to successful outcomes. Third, DAT110/6 dosage differentially modulated neural activation to reward-predicting cues in the caudate nucleus in the ADHD-CT and control groups.
Conclusions: The findings challenge the idea of a deficit in anticipation-related activation in the ventral striatum in male adolescents with ADHD-CT, while suggesting that the processing of reward outcomes is dysfunctional, consistent with a recent neurobiological model of the disorder. Preliminary evidence suggests that polymorphic variations in genes affecting dopamine signaling need to be taken into consideration when investigating reward-related deficits in ADHD-CT.
Method: We tested 29 male adolescents with ADHD-CT and 30 age-, handedness-, and gender-matched healthy controls who were selected for DAT110/6 haplotype dosage. Based on previous research, we focused our analysis on the ventral striatum and the caudate nucleus.
Results: Three main findings emerged. First, male adolescents with ADHD-CT did not differ from controls in terms of blood oxygen–level dependent (BOLD) fMRI response to reward-predicting cues (gain or loss-avoidance) in the ventral striatum. Second, male adolescents with ADHD-CT showed a relative increase, compared with controls, in the striatal BOLD response to successful outcomes. Third, DAT110/6 dosage differentially modulated neural activation to reward-predicting cues in the caudate nucleus in the ADHD-CT and control groups.
Conclusions: The findings challenge the idea of a deficit in anticipation-related activation in the ventral striatum in male adolescents with ADHD-CT, while suggesting that the processing of reward outcomes is dysfunctional, consistent with a recent neurobiological model of the disorder. Preliminary evidence suggests that polymorphic variations in genes affecting dopamine signaling need to be taken into consideration when investigating reward-related deficits in ADHD-CT.
| Original language | English |
|---|---|
| Article number | N/A |
| Pages (from-to) | 722–732.e9 |
| Number of pages | 11 |
| Journal | Journal of the American Academy of Child and Adolescent Psychiatry |
| Volume | 51 |
| Issue number | 7 |
| DOIs | |
| Publication status | Published - Jul 2012 |