Imaging receptor changes in human drug abusers.

This chapter will review the literature on differences in the brain chemistry of alcohol- and drug-dependent individuals compared to healthy controls as measured with positron emission tomography and single photon emission computed tomography. Specifically, alterations in dopamine, serotonin, opioid, and GABA systems in cocaine, alcohol, nicotine, and heroin dependence have been examined. These neurochemical systems are integrated and play significant roles in a final common pathway mediating addiction in the brain. One recurrent finding is that dopaminergic dysfunction is prevalent in both alcohol and drug dependent populations, and specifically there is a lower availability of dopamine type 2/3 receptors in cocaine-, alcohol-, nicotine-, and heroin-dependent individuals compared to healthy controls. The development of novel radiotracers that target additional receptor systems will further our understanding of the neurochemical basis of addiction.