Neural dysfunction during temporal discounting in paediatric Attention-Deficit/Hyperactivity Disorder and Obsessive-Compulsive Disorder
Luke J Norman1, Christina O Carlisi2, Anastasia Christakou3
1Department of Child and Adolescent Psychiatry, Institute of Psychiatry, Psychology and Neuroscience, King's College London, UK; Department of Psychiatry, University of Michigan, Ann Arbor, Michigan, USA.
Insights
Attention-Deficit/Hyperactivity Disorder (ADHD) and Obsessive-Compulsive Disorder (OCD) share neural deficits in self-control and temporal foresight, contributing to choice impulsivity. These overlapping brain dysfunctions suggest common mechanisms underlying impulsivity in both ADHD and OCD.
Area of Science:
- Neuroscience
- Psychiatry
- Cognitive Psychology
Background:
- Attention-Deficit/Hyperactivity Disorder (ADHD) and Obsessive-Compulsive Disorder (OCD) are linked to choice impulsivity, characterized by preferring immediate over delayed rewards.
- The specific neural mechanisms underlying choice impulsivity in ADHD and OCD remain incompletely understood, with questions about shared versus distinct pathways.
Purpose of the Study:
- To investigate the neural underpinnings of choice impulsivity in adolescent boys with ADHD and OCD compared to controls.
- To determine if impulsivity in ADHD and OCD is mediated by shared or distinct brain activation patterns.
Main Methods:
- Utilized functional magnetic resonance imaging (fMRI) during an individually adjusted temporal discounting (TD) task in 26 boys with ADHD, 20 with OCD, and 20 controls (aged 12-18).
- Compared brain activations related to immediate versus delayed reward choices across the three groups using a three-way ANCOVA.
Main Results:
- Boys with ADHD exhibited steeper discounting rates compared to controls; OCD patients did not significantly differ from either group.
- Both ADHD and OCD groups showed shared activation deficits in fronto-striato-insular-cerebellar regions crucial for self-control and temporal foresight.
- OCD patients additionally displayed distinct functional abnormalities in the right orbitofrontal and rostrolateral prefrontal cortex compared to controls.
Conclusions:
- Choice impulsivity in ADHD and OCD appears to be mediated by overlapping neural dysfunctions in regions governing self-control and foresight.
- Specific prefrontal cortex abnormalities in OCD may contribute to their choice impulsivity, extending previous findings.
- Findings suggest common and distinct neural pathways contributing to impulsivity in these neurodevelopmental disorders.
Abstract:
Both Attention-Deficit/Hyperactivity Disorder (ADHD) and Obsessive-Compulsive Disorder (OCD) are associated with choice impulsivity, i.e. the tendency to prefer smaller immediate rewards over larger delayed rewards. However, the extent to which this impulsivity is mediated by shared or distinct underlying neural mechanisms is unclear. Twenty-six boys with ADHD, 20 boys with OCD and 20 matched controls (aged 12-18) completed an fMRI version of an individually adjusted temporal discounting (TD) task which requires choosing between a variable amount of money now or £100 in one week, one month or one year. Activations to immediate and delayed reward choices were compared between groups using a three-way ANCOVA. ADHD patients had steeper discounting rates on the task relative to controls. OCD patients did not differ from controls or patients with ADHD. Patients with ADHD and OCD showed predominantly shared activation deficits during TD in fronto-striato-insular-cerebellar regions responsible for self-control and temporal foresight, suggesting that choice impulsivity is mediated by overlapping neural dysfunctions in both disorders. OCD patients alone showed dysfunction relative to controls in right orbitofrontal and rostrolateral prefrontal cortex, extending previous findings of abnormalities in these regions in OCD to the domain of choice impulsiveness.
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