Moreover, we identified an association with 1 SNP in DRD4 (rs12280580, p = 0.011, OR = 1.28) and AD. While no other groups have reported associations with this particular SNP and AD or disinhibitory psychopathology, several meta-analyses have noted associations with variants in DRD4 and urge for addictive substances (McGeary, 2009), ADHD (Gizer et al., 2009), and NS (Munafò et al., 2008). Further-more, we identified associations with the same SNP in DRD5 and two phenotypes, including withdrawal (rs7655090, p = 0.0017, β = −0.37) and the factor score (rs7655090, p = 0.0094, β = −0.34). The fact that DRD5 is associated with an alcohol-related trait and the factor score suggests it may contribute to AD through the broader disinhibitory spectrum. However, as only one SNP is associated with the factor score and this polymorphism has a low MAF (4.9%), this finding might represent a false positive.
