The unique developmental state of these systems parallels the unique response of the adolescent brain to alcohol. Acute alcohol exposure causes a robust increase in dopamine release within the nucleus accumbens [30], an effect that is most pronounced during adolescence [27,31]. This enhancement in dopamine release is consistent with the greater rewarding effects of alcohol in adolescents [19-21]. Alternatively, previous alcohol exposure significantly alters the dopamine response to an acute dose of alcohol [27]. In adolescents, alcohol exposure may interfere with development of the mesolimbic reward system, resulting in increased basal accumbal dopamine release and decreased dopamine D2 receptor expression [27,29,31]. Importantly, these changes are accompanied by a decrease in alcohol-evoked dopamine release upon subsequent alcohol exposure [27]. Decreased dopamine release and D2 receptor expression may create a hypodopaminergic state that reduces alcohol's rewarding effect. This state is reminiscent of Reward Deficiency Syndrome that arises when the reward system under-responds to natural or drug rewards and is hypothesized to increase reward seeking behaviors, such as risk taking and novelty seeking [32]. This idea is supported by observations that alcohol-induced changes
