Decreased reward-related brain function prospectively predicts increased substance use

Area of Science:

• Neuroscience
• Psychology
• Addiction Research

Background:

• Substance use disorder (SUD) is a global health issue linked to altered reward sensitivity.
• The fronto-striatal neural circuit, including the orbitofrontal cortex (OFC), ventral striatum (VS), and dorsal striatum (DS), underpins reward processing and motivation.
• Existing research presents conflicting views on whether SUD is associated with heightened or diminished reward sensitivity.

Purpose of the Study:

• To investigate if brain activity during reward anticipation predicts future substance use patterns.
• To examine the relationship between reward sensitivity, measured via fMRI, and subsequent substance use frequency and impairment.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to assess brain activity during a monetary incentive delay (MID) task in 79 participants.
• Participants underwent follow-up assessments of substance use frequency and impairment approximately 9.1 months later.
• Region-of-interest analyses focused on brain activation in the VS and DS during the reward anticipation phase.

Main Results:

• Reduced activation in the ventral striatum (VS) during reward anticipation was a significant predictor of increased substance use frequency at follow-up.
• Reduced activation in the dorsal striatum (DS) also predicted increased substance use frequency, though this did not reach statistical significance after multiple comparisons correction.
• These findings were robust after adjusting for baseline substance use and prior SUD diagnosis.

Conclusions:

• The study supports the reward hyposensitivity theory, indicating that diminished reward-related brain function is a risk factor for developing and maintaining problematic substance use.
• These results underscore the critical role of the fronto-striatal reward circuit in the pathophysiology of addiction.
• Understanding these neural mechanisms can inform targeted interventions for substance use disorders.