“Although there is an increasing line of evidence from preclinical models of addiction, there are only a few human studies that systematically assessed DNA methylation in addiction. Most of the studies were done on small cohorts and focused on one or a few candidate genes, except in the case of alcohol use where larger studies have been carried out.
A long line of evidence suggests that abnormal patterns of gene expression occur in brain regions related to drug addiction such as the nucleus accumbens, prefrontal cortex, amygdala, and the ventral tegmental area.
Using the “incubation of craving” model in rats trained to self-administer cocaine, and treated with either SAM or RG108, the genome-wide DNA methylation and gene expression landscape in the nucleus accumbens after short (1 day) and long (30 days) abstinence periods and the effects of epigenetic treatments were delineated. The main findings are:
- A long incubation period results in robust changes in methylation;
- Direct accumbal infusion of SAM that is paired with a “cue” after long incubation times increases drug-seeking behavior,
- Whereas a single treatment with RG108 decreases this behavior.
Importantly, the effects of these single administrations of a DNA methylation inhibitor remain stable for 30 more days. These data suggest that DNA methylation might be mediating the impact of “incubation” on the craving phenotype and that this phenotype could be reprogrammed by a DNA demethylation agent.”
The subject has a large scope, and a narrow aspect was presented in this paper. Rodent research by one of the coauthors that was cited, Chronic pain causes epigenetic changes in the brain and immune system, provided some relevant details.
The review covered neither human dimensions of the impacts of unfulfilled needs nor investigations of exactly what pain may impel human drug-seeking behavior. The “Implications for Diagnostic and Therapeutics” were largely at the molecular level.
https://www.sciencedirect.com/science/article/pii/S1877117318300164 “The Role of DNA Methylation in Drug Addiction: Implications for Diagnostic and Therapeutics” (not freely available)