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The reward system is a set of neuronal structures responsible for the processing of a number of psychological components, such as 'wanting', 'liking' and associative learning (Berridge & Robinson, 2003).These three processes occur together, 'wanting' dominates the initial appetitive phase, 'liking' dominates the consummatory phase, and learning occurs through the reward-behavioural cycle (Berridge et al., 2016). Both phenomena are underpinned by different brain circuits and neurotransmitter systems. The 'wanting' component is largely controlled by the dopaminergic system, whereas the 'liking' component is thought to be more mediated by opioid and GABAergic systems (Berridge & Robinson, 2003). The neural circuitry constituting the anatomical and neurochemical substrate for reward and pleasure was described several decades ago by Olds and Milner, who, after implanting electrodes in certain areas of the central nervous system (CNS) and administering electrical microstimuli, demonstrated a pleasure response in the animals (Olds and Milner 1954).Following this, it was proposed that the monoaminergic activity could underlie the neurochemical basis of pleasure, with the monoaminergic system playing an important role in drug reinforcement

Binge drinking (BD), a harmful pattern of alcohol consumption, is common during adolescence. Young adults with alcohol use disorders exhibit hippocampal alterations and episodic memory deficits. However, it is not known how these difficulties progress in community BD adolescents. Our objective was to analyze the relationship between BD trajectory and verbal episodic memory during the developmental period spanning from adolescence and to early adulthood. An initial sample of 155 male and female first-year university students with no other risk factors were followed over six years. Participants were classified as stable non-BDs, stable BDs and ex-BDs according to the third AUDIT item. At baseline, participants comprised 36 ♂/ 40 ♀ non-BDs (18.58 years), 40 ♂/ 39 ♀ BDs (18.87 years), and at the third follow-up, they comprised 8 ♂/ 8 ♀ stable non-BDs (25.49 years), 2 ♂/ 2 ♀ stable BDs (25.40) and 8 ♂/ 12 ♀ ex-BDs (24.97 years). Episodic memory was assessed four times with the Logical Memory subtest (WMS-III) and the Rey Auditory Verbal Learning Test (RAVLT). Generalized linear mixed models were applied. The results showed that, relative to non-BDs, stable BDs presented difficulties in immediate and delayed recall in the Logical Memory subtest. These difficulties remained stable over time. The short-term ex-BDs continued to display difficulties in immediate and delayed recall in the Logical Memory subtest, but long-term ex-BDs did not. The effects were not influenced by age of alcohol onset, frequency of cannabis use, tobacco use or psychopathological distress. In conclusion, BD during adolescence and young adulthood is associated with episodic memory deficits. Abandoning the BD pattern may lead to partial recovery. These findings are consistent with the vulnerability of the adolescent hippocampus to the neurotoxic effects of alcohol.

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