Cortical dopamine D2 receptors in type 1 and 2 alcoholics measured with human whole hemisphere autoradiography

Alcoholism has been associated with lower density of striatal dopamine (DA) D-2 receptors, but there is much less data on cortical DA D, receptors. We evaluated the [I-125]epidepride binding to DA D-2 receptors in Cloninger type 1 and 2 alcoholics and controls in frontal, temporal, and anterior cingulate cortices by using human postmortem whole hemispheric autoradiography, which provides high-resolution images corresponding to positron emission tomographic (PET) studies. Type 1 alcoholics had lower and type 2 alcoholics had higher DA D-2 receptor density in all cortical areas compared to controls. Although. the results did not reach statistical significance, the effect sizes were high. The DA D, receptor density in type 2 alcoholics decreased statistically significantly with age, and after correcting for age the binding values also fell below the level of controls. A statistically non-significant tendency towards a decrease of cortical DA D-2 receptors was seen in controls, whereas in the type 1 alcoholic group no consistent correlation or even tendency towards increase with age was observed. Our results give preliminary evidence that DA D-2 receptors in cortical areas may be lower among both groups of alcoholics, but not necessarily of same magnitude as in subcortical structures. The rapid decline of cortical DA D-2 receptors among type 2 alcoholics may have some relevance to their antisociality, because this trait tends to diminish with age. The absence of correlation or even tendency towards increase of cortical DA D-2 receptors with age seen in type 1 alcoholics may give further evidence that they have a pre-existing dopaminergic deficit. However, these results especially regarding aging effect must be considered as preliminary due to the different age-range of type 2 alcoholics compared to two other groups. (C) 2004 Wiley-Liss, Inc.