Dopamine transfer deficit
Summary
- The hypothesis concerns signals before a reward arrives, rather than a general shortage of dopamine in ADHD.
- Performance sustained by frequent rewards may not hold up with intermittent rewards, but experiments show mixed results.
The hypothesis concerns anticipation, not total dopamine
Research-backed
Tripp and Wickens propose that in children with attention deficit hyperactivity disorder (ADHD), dopamine responses shift less readily from rewards to cues predicting them. The hypothesis concerns signaling during anticipation, rather than an overall dopamine shortage(Tripp & Wickens, 2008).
Brain imaging found weaker responses during reward anticipation in the ADHD group(Plichta & Scheres, 2014). This also differs from rewards losing value in delay discounting, or finding waiting unpleasant in delay aversion.
Performance with frequent rewards may not hold with intermittent ones
Proposed in research
The hypothesis predicts that children with ADHD can perform similarly to a comparison group when every response is rewarded. With intermittent rewards, performance may be poorer because anticipatory signals provide less support for action(Tripp & Wickens, 2008; van & Tripp, 2020).
Performance under one reward schedule should therefore not be generalized to another. A 2020 review found limited, inconsistent evidence for this prediction: some experiments found no poorer performance in the ADHD group under intermittent rewards(van & Tripp, 2020).
The latest reward may outweigh the longer pattern
Proposed in research
The hypothesis also predicts that a single reward may influence the next action more than accumulated reward experience. A 2020 review described one child experiment: the comparison group consistently favored the option that earned more rewards overall. The ADHD group more often chose the option rewarded most recently(van & Tripp, 2020).
This offers a preliminary explanation for how a chance reward might steer action(van & Tripp, 2020).
Evidence
Emerging evidence
References (3)
- TheoryResearch Review: Dopamine transfer deficit: a neurobiological theory of altered reinforcement mechanisms in ADHDTripp Gail, Wickens Jeff R. (2008). Journal of Child Psychology and Psychiatry
- Meta-analysisVentral–striatal responsiveness during reward anticipation in ADHD and its relation to trait impulsivity in the healthy population: A meta-analytic review of the fMRI literaturePlichta Michael M., Scheres Anouk (2014). Neuroscience & Biobehavioral Reviews
- ReviewHow to Improve Behavioral Parent and Teacher Training for Children with ADHD: Integrating Empirical Research on Learning and Motivation into Treatmentvan der Oord Saskia, Tripp Gail (2020). Clinical Child and Family Psychology Review