Dopamine and Alcohol: A Review of in vivo PET and SPECT Studies.

Background: Alcohol-associated alterations of the dopaminergic (DA) system have been investigated via functional single-photon emission tomography (SPECT) positron emission tomography (PET) and imaging methods over many years, investigating presynaptic or postsynaptic markers, such as DA receptor and DA transporter availability, both with and without challenge. This review summarizes SPECT and PET studies on different levels of alcohol consumption to support the dimensional view of alcohol use disorder (AUD), ranging from acute consumption in social drinkers, individuals at high risk to patients with severe AUD and their association with blunted DA neurotransmission. Additionally, confounding factors of PET and SPECT studies of the DA system were discussed.

Summary: The included studies provided strong evidence that acute alcohol administration in social drinkers is followed by a DA release, particularly in the ventral striatum. In participants with AUD, DA release appears to be impaired as administration of a psychostimulant is followed by a blunted striatal DA. Furthermore, in recently detoxified participants with AUD, in vivo dopamine D2 and D3 receptor availability appears to be reduced, which may be a predisposing factor or the result of a neuroadaptive process influencing drug-induced DA release. DA transporter availability is reduced in AUD, whereas findings with respect to DA synthesis capacity are controversial.

Key messages: The DA system seems to be differently impaired during the development and persistence of AUD. In total, challenge studies (acute alcohol or psychostimulant administration) seem to be more consistent in their findings and might be less prone to the effects of confounders. Long-term studies with larger samples are required to better evaluate the alterations during chronic consumption and prolonged abstinence.