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Is Alcoholism Hereditary?
Alcohol use disorder (AUD) is a chronic brain disease. It has long been thought to be hereditary and research has linked it to specific genes.
Research shows that someone with a close relative, especially a parent or sibling, who has alcohol use disorder has a higher risk of developing AUD.
Although alcohol use disorder does seem to “run in families,” whether or not AUD and other addictions are hereditary isn’t a simple issue.
Genetics influence a person’s likelihood of developing AUD, but it isn’t the only factor. After all, there are plenty of people who have parents, siblings, and other family members with AUD who themselves have not developed the disorder.
Researchers estimate that genetics account for about 50 percent of a person’s risk for developing alcohol use disorder, while the environment and other things play an equal role.
Biological Factors of Alcohol Use Disorder (AUD)
Further complicating the link between biological factors and AUD, there are also multiple genes linked to the disorder. Certain genes increase a person’s risk, while others might decrease that risk.
How a person’s body metabolizes alcohol plays a role and if their body reacts poorly to moderate amounts of alcohol, they are less likely to develop AUD.
Despite children of people with AUD having a significantly higher risk for developing the disorder themselves, one 2011 study found that fewer than half of people with alcoholic parents developed AUD.
This could have been because they did not inherit any genes linked to AUD or their environmental influences prevented the expression of their inherited genes.
The role of environment in the development of AUD is also seen when comparing people with parents who are addicted to alcohol versus other members of the family. Growing up around people with addiction predisposes someone to develop AUD.
Learned behaviors also affect how a person perceives alcohol later in life. Even without a genetic component, a person can still develop AUD when raised in a certain type of environment.
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The “Alcoholic” Gene
Is there a gene that carries alcoholism?
Alcohol use disorder is related to genetics. But this doesn’t mean there is a specific gene you inherit which means you will develop the disorder. And not having genes linked to alcoholism doesn’t mean you won’t develop a problem with addiction, either.
Genetics are approximately 50 percent responsible for someone developing AUD. People predisposed to metabolize alcohol in a pleasurable way tend to have a greater risk for developing AUD.
According to a 2008 study by the National Institute on Alcohol Abuse and Alcoholism (NIAAA), genetic factors account for 40 to 60 percent of the reason people develop AUD. Since that study, specific genes were identified that seem to correlate with the development of the disorder. For example:
- ADH1B — This gene causes someone to feel hot and sweaty, develop a face and body flush, and increases feelings of sickness when they consume alcohol. This gene affects the liver’s ability to metabolize alcohol. Basically, when people with this gene drink they feel uncomfortable. It’s a deterrent to drinking too much or too frequently.
- GABRB1 — This gene is associated with the production of gamma-aminobutyric acid (GABA). Consuming alcohol alters the amount of GABA available to the brain, inducing relaxation and relieving anxiety. If someone has a mutation in this area and does not produce enough GABA while sober, they are more likely to abuse alcohol to feel better. (This is what is meant when someone says a person drinks to “self-medicate.)
- Beta-Klotho — Those who have this gene appear to be able to control their drinking. Most can consume a drink or two and then stop. Someone without this gene is less likely to control their urge to keep drinking alcohol.
In addition to these specific genes, researchers have also found the following factors to be involved in a person developing AUD:
- People with a smaller amygdala, which is the part of the brain associated with craving, are common in people with a family history of alcoholism
- People with abnormal serotonin levels seem to be genetically predisposed to developing AUD
- People with a genetic predisposition to AUD tend to lack the normal warning signals experienced by someone without the predisposition that tells them when to stop drinking
Genetics and Alcohol Tolerance
One of the most significant genetic factors in determining someone’s risk of developing AUD has to do with tolerance. Researchers have identified an alcohol tolerance gene that makes a person more susceptible to abusing alcohol. A person who tolerates higher amounts of alcohol has a higher risk of AUD as time goes on.
The so-called alcohol tolerance gene is cytochrome P450 isozymes and is found on chromosome 10. One study showed that the nearby regions controlling the activity of the CYP2E1 gene could be responsible for someone’s alcohol tolerance, as opposed to the gene itself being the issue.
Ultimately, researchers concluded that genetic variations in and around CYP2E1 affect the level of response to alcohol and the gene allows inferences to be made about how a person’s brain perceives alcohol.
This particular study did not directly look at people who were alcohol dependent. Researchers need more information before reaching any solid conclusions about alcohol tolerance and CYP2E1.
Researchers point out that other genetic factors and environment likely play a bigger role than any single gene in whether or not a person develops AUD.
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Alcohol and Genetics Statistics
Some of the most compelling statistics regarding alcohol and genetics include:
- More than 40 percent of US adults were exposed to AUD in either their family of origin or the family into which they married
- More than 6.5 million children live in homes with at least one parent with AUD
- Nearly 14 million US adults abuse alcohol or have AUD, and millions more engage in risky behavior related to alcohol
Environmental Factors that Also Play a Role
Research has shown that in most cases, environmental factors play as big a role in a person’s developing AUD as genetics does. Some of the most significant environmental factors affecting alcoholism include:
- How early a person began consuming alcohol. Those who drink in adolescence have a higher risk for developing AUD
- Parental attitudes toward alcohol. Children whose parents were extremely permissive when it comes to the idea of underage drinking have a greater chance of becoming addicted either as teenagers or adults.
- Abusive history. Children raised in stressful homes, especially those with sexual, physical, or verbal abuse, are at higher risk of developing AUD once they are adults.
- Mental health issues. A variety of disorders, including anxiety, depression, bipolar disorder, schizophrenia, and ADHD indicate a higher risk of developing AUD.
In contrast, children who grew up in homes with parental monitoring and support, and taught self-control and had access to community resources tended to have a lower risk for developing AUD.