Although it's not breaking news that alcoholism tends to run in families, researchers at the University of Pennsylvania and Yale School of Medicine have now determined that there are numerous genetic drivers linked to heavy drinking, alcoholism, or both.
Scientists in a massive genome-wide association study (GWAS)—recently published in the journal Nature Communications—searched for genetic variants in 274,000 participants enrolled in the United States Veterans Administration's Million Veteran Program (MVP), who had a history of heavy drinking or alcohol use disorder (AUD).
The MVP has multi-ethnic participants and is a voluntary research program from the Department of Veterans Affairs that includes individuals of African-American, Latino, Caucasian and Asian descent.
What is particularly interesting about the results of the study is how the 18 distinct risk regions fell between the study groups and the related implications for mental health and future research. The 5 genetic variants that were linked solely to those with AUD were also significantly associated with a genetic risk for other psychiatric disorders.
Notably, heavy drinking is a prerequisite for developing AUD, and 2 specific genes—SIX3 and DRD2—may have to be present to develop AUD. However, heavy drinking does not necessarily cause AUD.
First author of the study, Henry R. Kranzler, MD, views the distinct genetic independence of heavy drinking and AUD as a promising development for further research. "Focusing on variants only linked to AUD may help identify people at risk and find targets for the development of medications to treat it," Kranzler said in a news release on the study.
Furthermore, heavy drinkers facing their own set of negative effects may be able to receive help before overindulgence leads to a disorder. Studying the variants linked solely to heavy drinkers may help influence interventions aimed at reducing their alcohol consumption.
An undeniable strength of the study is its large size, but the opportunity to study genetic data from the MVP's biobank offered researchers the chance to pull from electronic health records and link genes to health-related traits with great statistical power—more than can normally be gained in genome-wide studies.
In addition to the genetic variants linked to heavy drinking, AUD or both, researchers found 111 traits or diseases correlated with AUD, including a greater risk for psychiatric disorders or insomnia. Subjects also tended to be of lower intelligence. On the other hand, heavy drinkers in the study were more educated, with a lower risk of coronary artery disease.
According to the National Institute on Alcohol Abuse and Alcoholism (NIAAA), approximately 16 million Americans suffer from AUD, with excessive drinking causing a myriad of adverse social, medical, and psychiatric consequences. Additionally, around 88,000 Americans die each year from alcohol-related causes. There are monetary costs as well, with alcohol misuse costing the US almost $300 billion a year.
This underscores the urgency to continue identifying and studying genetic variants and health outcomes for heavy drinkers and alcoholics, especially in understanding and treating cases where variants diverge by traits.
Heredity, genetic factors and environmental influences all play a role in heavy drinking and AUD, and many variants believed to be linked to AUD remain unidentified. Other research has shown that about half of the risk for alcoholism can be contributed to genetics.
However, researchers with extensive knowledge in addiction and misuse of alcohol are hard at work to help us better understand and treat AUD, as well as intervene appropriately for heavy drinkers. The long-term clinical implications in diagnosis of risk and development of medications and other treatments seem to offer promise for those with AUD, or who are at risk of developing it.