genotype, which is significantly lower than both homozygous groups (21.2 ± 8.1 and 23.8 ± 7.5 for the Met/Met and Val/Val homozygous groups, respectively) (p = 0.048) [91]. Another investigation of the association between BDNF rs6265 SNP and heroin dependence in a population of 487 Han Chinese, showed a significantly higher frequency of G alleles in heroin-dependent subjects than controls (χ2=10.150, P=0.001, OR=1.339, 95% CI=1.119–1.602) [89]. Taken together, these results support the hypothesis that the rs6265 SNP in the BDNF gene may influence a variety of psychological and behavioural traits including depression, euphoria, age of onset of substance abuse, and heroin dependence.
