As in tobacco behavior, case/control- and family-based haplotype analyses with 43 SNPs within the NCAM1-TTC12-ANKK1-DRD2 gene cluster have been performed in studies of alcohol dependence (AD) (Yang et al. 2007) and drug dependence (DD) (Yang et al. 2008). This evidence concerns the gene DRD2 and Alzheimer disease.