In 2006, the National Institute on Drug Abuse (NIDA) supported research that reviewed the human genome as part of an effort to identify Americans most at risk for developing an alcohol use disorder. Before this groundbreaking study, studies showed that alcohol abuse runs in families, but it could not point to the genetic basis of this finding. The study was possible because the Human Genome Project (2003) was able to identify every gene that exists in human DNA.
The NIDA study found that the genes involved in alcohol abuse were concentrated in 51 chromosomal areas in the body. The genes involved are players in a variety of basic body function, such as cell-to-cell communications, the control of protein synthesis, cell-to-cell interactions, and regulation development. It may be that dysregulation in these areas makes a person vulnerable to alcohol or other drug abuse. That fact that the dysregulation or problems can be encoded in the genes means that parents can pass these genes on to their children who in turn pass them on to their children, and so on.
The following facts and statistics further illuminate the connection between alcohol abuse and genetics:
- The children of people with an alcohol use disorder face a twofold greater risk of developing an alcohol use disorder.
- A genetic disposition to alcohol abuse does not mean a person will develop an alcohol use disorder. Less than half of the children of people with an alcohol use disorder will develop an alcohol use disorder.
- Individuals can develop an alcohol use disorder even if they are not genetically disposed to do so. A person’s environment can strongly influence the development of an alcohol use disorder.
- There is no gene or set of genes that puts a person at risk specifically for alcohol abuse. Rather, one possibility is that there are variations in genes that get expressed in different ways in a carrier’s body. For example, gene variations can predispose individuals to depression, which in turn can predispose them to alcohol abuse.
- Knowing which genes are involved in creating an elevated risk for an alcohol use disorder can help researchers to match treatment to genes. For instance, the addiction treatment drug naltrexone may work on specific genes. Psychotherapy may also effectively target certain genes versus others.
What the Research Shows About Alcoholism and Genetics
As an article published on Psychology Today discusses, studies of twins have revealed helpful information about the connection between genes and an alcohol use disorder. In specific, studies that compare fraternal twins and identical twins can be particularly insightful. Among identical twins, their 23 chromosome pairs are exactly the same (i.e., identical twin are monozygotic). This explains why they look the same. Fraternal twins do not have identical chromosome pairs; hence, they look different from each other. If addiction has a genetic basis, it would be expected that identical twins who carried the genes involved in addiction would similarly express them (though environmental factors can be involved). The University of Washington and the University of Queensland conducted a large-scale male and female twin study involving 5,889 participants.
The topic of genetics and an alcohol use disorder only underlines the complexity of alcohol abuse. No one is immune from the risk of developing an alcohol use disorder.
The study found that among identical male twins, if one had an alcohol use disorder, there was a 50 percent likelihood that the other would at some point in his lifetime. Among identical female twins, there was a 30 percent likelihood. This finding supports at least a couple possible insights.
First, there may be something about identical twin males, genetically speaking, that makes them more likely to express an alcohol use disorder if one twin has one as compared to females (50 percent versus 30 percent). As researchers have noted, other genes (beyond the cluster that NIDA found) can play a role in the development of an alcohol use disorder. Second, if an identical twin has a sister or brother who has an alcohol use disorder, the odds are not that they will also develop one. Among males, it’s 50 percent, not 51 percent, which would mean that the development of an alcohol use disorder was more likely than not.
The topic of genetics and an alcohol use disorder only underlines the complexity of alcohol abuse. No one is immune from the risk of developing an alcohol use disorder. As a rule of thumb, a person increases their risk of addiction to alcohol if they regularly consume a high volume of this drug. For this reason, there is a general advisement that individuals “drink responsibly,” which means keeping intake to a manageable level. To use a legal standard, individuals could feasibly enjoy alcohol while being mindful to constantly keep their blood alcohol content (BAC) to below 0.08 percent. In other words, individuals are considered legally too drunk to drive if their BAC is 0.08 percent or higher.
The site Be Responsible About Drinking provides guidance. For example, a 180-200 pound male may be able to consume as many as three alcoholic drinks and keep his BAC below 0.08 percent. A female in the weight range of 140-160 pounds may be able to have two drinks and keep her BAC to below 0.08 percent. These are rough estimates, and of course, the time period over which a person drinks is significant. For every 40-minute period, the BAC should usually lower by 0.01 percent.
Alcohol consumption is legal in the US, and there are few barriers to a person drinking too much, which can predispose them to developing an alcohol use disorder. Yes, genes play a role, but they do not fate a person to alcohol abuse. Research shows that the children of people with an alcohol use disorder may have to be especially cautious, but everyone needs to be vigilant when it comes to alcohol consumption. Even the most advanced research on genetics will likely only help people to reduce their risk of developing an alcohol use disorder, rather than eradicate it.
It’s Never Too Late to Get Help