Neuropsychopharmacology. 2016 Jan 21. doi: 10.1038/npp.2016.11.
While reward processing appears altered in addiction, few studies track neuro-functional changes following treatment or relate these to measures of reduced drug use. The current study examined neuro-functional alterations in reward processing in cocaine dependence (CD) pre- and post-treatment to determine whether these changes relate to clinically meaningful outcome indicators. Treatment-seeking CD outpatients (N=29) underwent functional magnetic resonance imaging while performing a monetary incentive delay task (MIDT) pre- and post-treatment. The MIDT parses anticipatory from outcome phases of reward/loss processing. Abstinence indicators (negative urines, days abstinent from cocaine during follow-up) were collected throughout treatment and up to one year later. Healthy control (HC) participants (N=28) were also scanned twice with the MIDT. Relative to pre-treatment, at post-treatment CD participants demonstrated increased anticipatory reward activity in the midbrain, thalamus and precuneus (pFWE<0.05). Increased midbrain activity correlated with cocaine abstinence during the 1-year follow-up. Ventral striatal (VS) activity during loss anticipation correlated negatively with negative urine screens. HC group test-retest results showed decreased ventromedial prefrontal cortex activity during winning outcomes. CD-HC group-by-time differences revealed increased left inferior frontal gyrus activity in the CD group during anticipatory phases at post-treatment. In CD participants, increased post-treatment activity in dopamine-innervated regions suggests lowered thresholds in anticipatory signaling for non-drug rewards. Midbrain and VS responses may represent biomarkers associated with CD abstinence. Abstinence-related neurobiological changes occur in similar regions implicated during active use and may possibly be used to track progress during short and long-term recovery.
Neuropsychopharmacology accepted article preview online, 21 January 2016. doi:10.1038/npp.2016.11.