Chennai: Excessive consumption of alcohol, resulting in alcohol use disorder (AUD), alters DNA in men, and these changes can persist for at least three months during both complete withdrawal and reduction in consumption, suggests a new study from National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru.
The study has implications for treatment of AUD, which is often treated by forcing the patient to abstain from alcohol and frequently results in chronic relapse.
The study was conducted on 52 men aged 21 to 40 years, who attended the NIMHANS Center for Addiction Medicine outpatient clinic from March 2015 to April 2016, seeking treatment for alcohol problems.
The participants were compared against a control group of 52 men of similar age.
The researchers found that after three months of treatment, among both men who reduced alcohol consumption as well as those who abstained, changes in DNA induced by AUD persisted.
The results were published last month in the American Journal of Medical Genetics.
Alcohol disorder and DNA changes
AUD encompasses conditions commonly referred to as alcohol abuse, alcohol dependence, alcohol addiction, and alcoholism. The disorder is defined by behaviours such as binge drinking and inability to moderate consumption, and addiction.
In India, 29 per cent of men aged 15 to 54 consume alcohol — 12 per cent do so daily and 41 per cent do so weekly. AUD accounts for 3 million deaths or 5.3 per cent of all deaths globally every year, according to the World Health Organisation.
AUD induces DNA methylation, or the addition of methyl groups to DNA, which causes changes in the DNA but does not change the sequence itself.
DNA methylation regulates, and can suppress, gene expression — the processes by which information from a gene is used to produce a protein, which aids in other biological and metabolic processes in the body.
The researchers note that such suppressed gene expression has also been associated with cancers in the body.
The team compared the participants seeking treatment — with an average age of 33 and alcohol dependence for eight years, with mean alcohol consumption of approximately 13 units a day — with the control group that did not suffer from AUD.
One unit is 10ml or 8g of pure alcohol, which is approximately the amount of alcohol an average adult can process in an hour.
The researchers found that after three months of standard treatment, DNA methylation persisted during the three-month follow-up period as compared to control participants, who did not suffer from AUD but whose alcohol and nicotine consumption was not factored in.
The team also found that the amount of DNA did correlate with the age of first exposure to alcohol consumption.
Admittedly, the study has key limitations — mainly, researchers were unable to establish whether methylation was caused by AUD or if it was the cause for AUD itself.
They also did not study methylation in the brain, only in the blood.
Moreover, the researchers did not have enough data to perform a follow-up beyond three months.
Additionally, participants in the trial represented the “severe end of the AUD spectrum” and thus the results are likely not applicable to those without alcohol dependence, the authors said.
The findings are also applicable only to men, and to those who were able to seek treatment in metros such as Bengaluru.
Finally, the authors clarified that 52 test participants are too few a number for definitive results, adding that further studies are needed, especially among those who switch to abstinence after AUD.
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