Nora D. Volkow, M.D.

SUMMARY: Addiction is a disorder that involves complex interactions between a wide array of biological and environmental variables. Strategies for its prevention and treatment therefore, necessitate an integrated approach incorporating systems of analysis that span the molecular to the social. Pairing rapidly evolving technologies such as neuroimaging with sophisticated behavioral measurement paradigms has allowed extraordinary progress in elucidating many of the neurochemical and functional changes that occur in the brains of addicts. Although large and rapid increases in dopamine have been linked with the rewarding properties of drugs, the addicted state, in striking contrast, is marked by significant decreases in brain dopamine function. Such decreases are associated with dysfunction of prefrontal regions including orbitofrontal cortex (involved in salience attribution) and cingulate gyrus (involved in inhibitory control). Dysfunction of brain circuits involved in motivation and drive, inhibitory control, reward, and memory and learning all contribute to addiction. Treatments for addiction that include altering reward and motivational systems, interfering with conditioned responses, and promoting brain plasticity are currently being studied.