Rs1799971 has been associated with the duration of methamphetamine-induced psychosis in a case-control study of individuals with methamphetamine dependence/psychosis; G/G individuals were more likely to become psychotic within 3 years of their first methamphetamine intake (Ide et al. 2004). In a more recent study using the same population, the previous association did not replicate, but the G/G genotype of an additional SNP in OPRM1 (IVS2 + G691C; rs2075572; G/C) was associated with both methamphetamine dependence and psychosis (Ide et al. 2006). These results suggest the possibility that additional variants underlie chronic methamphetamine response, although rs1799971 has been the main target of the literature in investigating acute and chronic stimulant responses.
