In recent years there has been a proliferation of interest in executive functions (EF) as they relate to alcohol and other substance use disorders. EF refer to an interrelated set of self-regulatory skills and abilities related to goal-directed behavior [74] including attention, working memory, planning, and cognitive flexibility. EF share a highly heritable (99%) common factor [75] and alcohol dependence severity is associated with impaired EF [76]. These EF impairments among alcohol dependent individuals are to be expected given the toxic effects that alcohol has on the frontal lobes; however, it has been proposed that these EF deficits may predate the onset of disorder and qualify as an endophenotype [77]. For example, unaffected relatives of alcohol or drug dependent probands also have lower EF (as measured in tasks tapping cognitive flexibility and inhibition) compared to healthy controls [78, 77]. In one of these samples, analyses of the brain-derived neurotrophic factor (BDNF) Val66Met polymorphism found that the Met allele was associated with lower EF [78]. However, variation in this same polymorphism is not associated with AUD [79].
