Variations in GABRA2 have been most frequently associated with addictions and related behaviors (Covault et al., 2004; Edenberg et al., 2004; Lappalainen et al., 2005; Dixon et al., 2010; Enoch et al., 2010), but there is also a robust association of GABRB1 with AD comorbid with other substance dependence and psychiatric illnesses (Kertes et al., 2011; Yang et al., 2012). This evidence concerns the gene GABRA2 and Alzheimer disease.