These findings provide first evidence in humans that the PDYN polymorphism modulates neural processes associated with the anticipation of rewards, which ultimately may help to explain differences between genotypes with respect to addiction and drug abuse.
Vulnerability and resilience can be due to pre-existing (e.g., genetic) factors, or epigenetic modifications of the OPRK1 or PDYN genes during the addiction cycle.
To address this hypothesis we analyzed PDYN mRNA levels in the dorsolateral prefrontal cortex (dl-PFC) and hippocampus, both involved in cognitive control of addictive behavior and PDYN promoter SNP genotype in alcohol-dependent and control human subjects.