Nearly 15 million Americans 12 years of age and older were dependent on or abused alcohol in 2010.1 The high prevalence of problem alcohol use worldwide has been estimated to cause 2.5 million deaths each year,2 not to mention the exorbitant costs associated with excess morbidity3 and loss of productivity.4 The chronic and relapsing nature of alcoholism, just like that of every other substance use disorder, is one of the major obstacles to its successful treatment. This is why the search for predictive biomarkers to help clinicians select and monitor a therapeutic course of action and to help researchers evaluate new therapeutic interventions is so urgent.