At-risk for pathological gambling: imaging neural reward processing under chronic dopamine agonists

Area of Science:

• Neuroscience
• Psychiatry
• Pharmacology

Background:

• Dopamine receptor agonists are used to treat Parkinson's disease and restless legs syndrome (RLS).
• These medications are associated with impulse control disorders, including pathological gambling (PG), in some patients.
• The neurobiological mechanisms underlying this association are not fully understood.

Purpose of the Study:

• To investigate the neurobiological effects of dopamine receptor agonists on reward processing in RLS patients.
• To examine how medication influences neural responses during a gambling task.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used in a within-subjects design.
• Twelve female RLS patients were scanned twice: once on dopamine receptor agonists and once after a washout period.
• Participants performed a gambling task involving reward expectation and outcome processing.

Main Results:

• Ventral striatal activation during reward expectation was observed only when patients were on medication.
• Neural responses to reward receipt or omission differed significantly between medication and washout conditions.
• Orbitofrontal cortex activation remained unaffected by medication.

Conclusions:

• Dopamine receptor agonist medication alters neural signaling of reward expectation, potentially increasing appetitive drive.
• Medication leads to altered neural processing of negative consequences, possibly impairing learning.
• Intact orbitofrontal function may protect against developing manifest impulse control disorders.