How Do Genes Affect Alcoholism?

30 Aug How Do Genes Affect Alcoholism?

While it isn’t getting the spotlight of the opiate epidemic, alcoholism is on the rise. On average, alcohol resulted in deaths in 12,460 car crashes, 7,541 falls, 8,404 poisonings (not alcohol poisonings) and 1,089 fires. This is just to name a few of more than 88,000 alcohol-related deaths each year, in data collected between 2006-2010 (1). In the first decade of the 2000’s alcoholism rose 49% nationwide, from 8.5%-12.7% (2). One in eight American adults now meets diagnostic criteria for alcoholism, aka alcohol use disorder (3).

Alcoholism is known as a family illness in that the behavior of one alcoholic individual affects the well being of the entire family system. But alcoholism is also known as a family illness because it has a genetic component, with children of alcoholics being four times more likely than the general population to develop alcohol problems (4). Genes alone do not determine whether someone will develop alcoholism, but research shows that genes are responsible for about half of the risk (5).

Genetics research has traced some aspects of alcoholism down to nuances at the single gene level. A number of studies found an association between alcoholism and a single location within a gene. DNA is coded in A’s T’s C’s and G’s much like the 0’s and 1’s of computer code. In one such study, a single change to an “A” in that portion of DNA correlated with 20% higher odds of being an alcoholic (6).

How do you explain such a small genetic change having such a big impact on the likelihood of being an alcoholic? One example can be seen in how the body processes alcohol. Alcohol needs to be digested and processed by the body, just like most things we ingest. As alcohol is converted from one chemical to another, different people (and their different sets of genes) can process alcohol more quickly or more slowly. If your body processes alcohol more slowly, alcohol may just “feel worse” than if your body processes alcohol more quickly. People with these slow genes are less likely to enjoy the effects of alcohol, and may get more of a feeling of toxicity rather than euphoria.

While alcohol abuse is known to result in liver damage, accidents and death, drinking can also put one at a higher risk of certain diseases due to genetics. For example, one gene ALDH2 causes deficiency in an enzyme linked to esophageal cancer. Individuals lacking this enzyme are already at escalated risk of developing the cancer and heavy drinking further increases the likelihood (6).

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1. “Alcohol and Public Health: Alcohol-Related Disease Impact (ARDI).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, nccd.cdc.gov/DPH_ARDI/Default/Report.aspx?T=AAM&P=f6d7eda7-036e-4553-9968-9b17ffad620e&R=d7a9b303-48e9-4440-bf47-070a4827e1fd&M=8E1C5233-5640-4EE8-9247-1ECA7DA325B9&F=&D=.
2. Grant, PhD Bridget F. “Prevalence of Alcohol Use, High-Risk Drinking, and DSM-IV Alcohol Use Disorder.” Journal of the American Medical Association Psychiatry, JAMA, 9 Aug. 2017, jamanetwork.com/journals/jamapsychiatry/fullarticle/2647079.
3. Ingraham, Christopher. “One in Eight American Adults Is an Alcoholic, Study Says.” The Washington Post, WP Company, 11 Aug. 2017, washingtonpost.com/news/wonk/wp/2017/08/11/study-one-in-eight-american-adults-are-alcoholics/?utm_term=.6bc433c764cd.
4. “Additional Information.” National Institute on Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, pubs.niaaa.nih.gov/publications/FamilyHistory/famhist.htm.
5. “Genetics of Alcohol Use Disorder.” National Institute on Alcohol Abuse and Alcoholism, U.S. Department of Health and Human Services, www.niaaa.nih.gov/alcohol-health/overview-alcohol-consumption/alcohol-use-disorders/genetics-alcohol-use-disorders.
6. “Barfly Genetics.” 23andMe Blog, 11 Dec. 2015, blog.23andme.com/23andme-research/snpwatch/barfly-genetics/.