Relationships Between Alcohol Intake and Mitochondrial DNA Methylation in the Human Prefrontal Cortex and Nucleus Accumbens

Despite the critical role of mitochondria in confronting alcohol challenges and providing energy, to date, there are no studies describing the effect of alcohol on mitochondrial epigenetics in energy-craving brain tissues. Focusing on the human nucleus accumbens (NAcc) and prefrontal cortex (PFC), we aimed to examine the effect of alcohol on mitochondrial DNA methylation. We collected 105 brain tissue samples from 53 deceased individuals, classified into no antemortem alcohol use (n = 34), alcohol-ingested (n = 9) and alcohol-fermented (n = 10). Using whole-genome bisulphite sequencing, we constructed an alcohol intake (ALC) index summing the effect of differentially methylated cytosine sites between individuals with alcohol-ingested and individuals without antemortem alcohol use. Compared to the group of alcohol-ingested, lower ALC index scores in both the NAcc and the PFC were found not only in the group of no antemortem alcohol use (p = 7.70 × 10-5 in the NAcc; 1.03 × 10-5 in the PFC) but also in the group of alcohol-fermented (p = 5.67 × 10-3 in the NAcc; 5.49 × 10-4 in the PFC). The findings of the differentially methylated cytosines and the performance of the ALC index were supported by permutation tests. In addition, we found that the individuals with an alcohol consumption history had higher ALC index scores in the NAcc (p = 0.044) but not in the PFC compared to those without an alcohol consumption history. This study revealed the immediate and cumulative effects of alcohol on the mitochondrial epigenetics of the human brain and provided evidence to determine antemortem alcohol use.