The National Institute on Alcohol Abuse and Alcoholism (NIAAA) defines alcohol use disorder (AUD) – formerly alcoholism or alcohol addiction – as a form of problem drinking that has become severe, with compulsive behaviors and physical dependence associated with the condition. About 16 million people in the United States struggle with AUD, including 15.1 million adults ages 18 and older, and 623,000 adolescents between the ages of 12 and 17. Because this condition is so prevalent, especially for substance use disorders, medical researchers have worked hard to understand the potential causes of AUD. With a goal to help predict if a person may develop this chronic illness, research in the field also aims to find new, effective approaches to treatment.
What Causes Alcohol Use Disorder?
Typically, addiction is considered to involve several complex risk factors:
- Genetics
- Family history
- Current environment
- Gender
- Mental health condition
Stress in one’s work or home life may trigger an addiction. When the person drinks alcohol, for example, they may feel relaxed and happy compared to the stress they feel when they are sober. This reinforces the desire to use alcohol as a coping mechanism for stress. Those who have mental illnesses, especially anxiety, depression, bipolar disorder, and schizophrenia are very likely to struggle with co-occurring alcohol use disorder. Women are at risk of developing AUD faster than men due to differences in body mass, hormones, and metabolism.
Genetics and family history are the most correlated with risk of AUD; in fact, genetic risk is about half of the problem, while family history is the other half. Certainly, genetics are passed down through families, but family history also includes the environment in which one was raised. Childhood abuse, parental struggles, and mental illness in close family members all contribute to the risk of developing an addiction to drugs or alcohol.
The Genetics of Alcohol Use Disorder
To understand how the risk of AUD is passed down from generation to generation, scientists have examined genetics in family lineages to identify potential hereditary causes of this chronic disease. In 2012, some of the first research on the genetics of alcohol abuse and addiction was published. Medical researchers reported 11 pairs of genes that were associated in some way with a risk of drinking too much and developing compulsive behaviors around alcohol. Based on research using mice, the team then found these genes in groups of humans. Many of those 11 pairs were also associated with neuropsychiatric disorders aside from AUD, like Parkinson’s disease, schizophrenia, bipolar disorder, anxiety, and cocaine addiction.
Some of the genes associated with increased risk of developing AUD include:
- ADH1B: This gene has a low prevalence in European, specifically Caucasian, populations, but is very prevalent in East Asians; one report found 70 percent of East Asians had this gene. Variants on this gene are associated with the alcohol flush reaction, which can cause a person to feel hot and sweaty, make their face and body flush, and increase feelings of sickness. Only about 5 percent of surveyed European populations feature this gene, which is involved in the liver’s ability to metabolize alcohol to acetaldehyde and then to acetate. When there is too much acetaldehyde not readily metabolized into acetate, the person develops the flush reaction, which is uncomfortable. It is considered a deterrent for alcohol use disorder, so in populations that have a lower frequency of this gene, like Europeans, there is an increased risk of developing AUD, with fewer genetic deterrents.
- GABRB1: Another study identified mutations of the GABRB1 gene, which can increase the risk of AUD because of changes to gamma-aminobutyric acid (GABA). Because alcohol changes how much GABA is available to the brain, inducing relaxation and relieving anxiety or stress, mutations in this area leading to less GABA production while sober may prompt a person to abuse alcohol to feel better (the self-medication hypothesis).
- Beta-Klotho: This gene is associated with drinking less rather than experiencing pleasant feelings from drinking more. People with the beta-Klotho gene appear to be able to control their drinking, usually consuming one or two drinks and then successfully stopping. This gene is triggered by two hormones, which can determine whether the person also has a sweet tooth, preferring sugary tastes; if the person does not have the gene, they are less likely to control their urge to keep drinking alcohol.
These are only three of the numerous genes found to be associated with substance abuse, including AUD. Some genes can help a person regulate their alcohol consumption or avoid the substance altogether; others increase the person’s risk of abusing alcohol.
Gene expression is affected by environment. If a person grows up in a house with a parent who abuses drugs, struggles with mental illness, suffers a major financial setback or similar stress, and the child has a gene linked to alcohol use disorder, they are very likely to develop this condition later in life. Prevention and education programs can address this risk as part of regular medical checkups. Genetics are understood to be a component of AUD, but not the sole cause.
Alcohol Use Disorder Should Be Treated Now
Many of the existing genetic experiments examining substance abuse and addiction involve mice, which are bred to be good analogues of human genetics. However, there are few long-term studies that have conclusively linked specific genetic traits to humans who struggle with AUD. It is pretty well understood that high-stress environments and trauma are linked to alcohol use disorder, so appropriate therapy to manage these mental and behavioral conditions is extremely important.
Concerns about alcohol consumption should be addressed by a medical professional. Feeling out of control in regard to drinking and feeling as though one drinks too much are indicators that there is a problem. Fortunately, there is help. Medically supervised detox programs and evidence-based rehabilitation programs are available that specialize in treating AUD. In the future, there may be genetic therapies that help people control how much alcohol they consume; for now, behavioral therapies have proven very effective at managing these chronic health conditions.
