Serotonin transporter availability correlates with alcohol intake in non-human primates

A low level of alcohol intoxication upon initial exposure and impulsive aggressiveness predispose humans to alcoholism. In non-human primates, central serotonin transporter availability and turnover rate were associated with aggressive behavior and a low response to initial alcohol exposure. We assessed the respective effects of these factors on alcohol intake in a free choice paradigm. Serotonin transporter availability in the raphe area, the origin of central serotonergic projections, was measured with single-photon emission computed tomography and the radioligand [¹²³I]β-CIT in 11 rhesus monkeys with low and high central serotonin turnover. The amount of alcohol intake in the 3-month observation period was positively correlated with serotonin transporter availability (R = 0.76, P = 0.006), but not with aggressiveness (R = 0.19, P = 0.6) or alcohol response upon first exposure (R = -0.48, P = 0.2). In a linear multiple regression analysis with serotonin transporter availability, alcohol response, and aggressiveness as independent variables, 82% of the variance of alcohol intake was explained and serotonin transporter availability emerged as the only statistically significant factor (β = 7.81, P = 0.006). These observations indicate that there may be a direct relationship between serotonin transporter availability and alcohol intake after controlling for aggression and alcohol response on first exposure.