Striatal Dopamine D2 Receptor Availability Predicts the Thalamic and Medial Prefrontal Responses to Reward in Cocaine Abusers Three Years Later

prefrontal cortex; cocaine addiction; monetary reward ABSTRACT Low levels of dopamine (DA) D2 receptor availability at a resting base-line have been previously reported in drug addicted individuals and have been associ-ated with reduced ventral and dorsal prefrontal metabolism. The reduction in DA D2 receptor availability along with the reduced ventral frontal metabolism is thought to underlie compromised sensitivity to nondrug reward, a core characteristic of drug addiction. We therefore hypothesized that variability in DA D2 receptor availability at baseline will covary with dynamic responses to monetary reward in addicted individu-als. Striatal DA D2 receptor availability was measured with [11C]raclopride and posi-tron emission tomography and response to monetary reward was measured (an average of three years later) with functional magnetic resonance imaging in seven cocaine-ad-dicted individuals. Results show that low DA D2 receptor availability in the dorsal striatum was associated with decreased thalamic response to monetary reward; while low availability in ventral striatum was associated with increased medial prefrontal (Brodmann Area 6/8/32) response to monetary reward. These preliminary results, that need to be replicated in larger sample sizes and validated with healthy controls, suggest that resting striatal DA D2 receptor availability predicts variability in functional responses to a nondrug reinforcer (money) in prefrontal cortex, implicated in behavioral monitoring, and in thalamus, implicated in conditioned responses and expectation, in cocaine-addicted individuals. Synapse 64:397–402, 2010. VC 2009 Wiley-Liss, Inc