Molecular imaging in alcohol dependence.

The cellular mechanisms of alcohol's effects in the brain are complex, targeting multiple transmitter systems. Molecular imaging has been used to study the effects of alcohol and alcohol use disorders on these various systems. Studies of dopaminergic indices have provided robust evidence for deficits in D2-mediated transmission in the striatum of chronic recently detoxified alcoholics. Their presence in the at-risk state prior to excessive drinking, and their recovery after long-term sobriety, are unclear and represent an active area of current research. Investigations of the GABAergic system have shown generalized deficits in various brain regions in the chronic abstinence phase. Studies of the opiate system have suggested alterations in some subtypes in discrete brain regions, including the ventral striatum, while studies of serotonin have been negative and those of the cannabinoid system have been inconclusive. Future investigations should target the glutamatergic system, which plays an important role both in the acute intoxicating effects of alcohol as well as in the long-term effects associated with dependence.