Genetics and Substance Abuse

Substance use problems often involve a complicated spectrum of cause and effect, thought and behavior, and actions and repercussions. You may wonder if some people more predisposed to develop an addiction than others. Unfortunately, the answers are rarely simple. Looking at the relationship between genetics and substance abuse helps us to further understand the nature of drug or alcohol addiction.

The Genes that Make Us

Genetics is the study of the biological process in which each person inherits certain genes from their biological parents. Genes are cellular building blocks of our bodies, and they carry DNA that offers instructions on how we will appear, grow, and develop. Our parents pass genes down to us at conception, but those genes may appear in a variety of ways.¹

The vast array of possible genetic combinations makes us all unique human beings that carry a wide variety of physical and behavioral features and mannerisms. Just as children inherit their parents’ eye color, skin color, height, or hair color, they may also inherit the genes that carry the risk of certain diseases or other medical conditions.²

Genetics and Substance Abuse: The Study of the D2 Subtype Gene

Modern researchers are very interested in the specific biological differences that make a person vulnerable to addiction. They have concluded that there is not one particular gene that will definitely lead to addiction. There are, instead, many gene combinations and markers that make a person more vulnerable to addiction than others. Addiction vulnerability involves a lot of very complex factors that include both genes and life experience.³

For instance, the study of one gene in particular, the D2 subtype, is one of the most studied cases of genetic vulnerabilities.

When a person takes drugs or alcohol, the brain is artificially stimulated to produce dopamine, a neurotransmitter that is responsible for feelings of pleasure and reward in the brain. The D2 subtype responds to the presence of dopamine, so people who do not have this gene have a stronger compulsion for alcohol and will consume alcohol in larger amount when compared to other individuals who do have the gene. This is because people who lack the D2 gene do not feel the effects of dopamine as much as people who have the gene, so they often drink longer and harder to achieve the same buzz.⁴

The D2 study is just one example of an isolated gene study and further research is still needed. Every person is unique. It is important to know that anyone can struggle with substance use, and it may be difficult to determine which, if any, genes contribute to any particular addiction. One genetic test will not rule out the potential dangers of unhealthy substance use.

Every person’s body will react very differently to the effects of drugs and alcohol – some may be hooked on their first shot or smoke, while some people can knock back drink after drink before showing any signs of a problem.

Instant Dependence vs. Neuroadaptation

Can people become instantly addicted after one drug use? The jury is still out. Recent research indicates that a number of genetic factors contribute to potential addiction.

For instance, the way a person’s brain handles neurochemicals like dopamine may be an inherited trait. Some people appear to be pre-wired for addictive traits, and after one try, they may instantly intensely crave those substances that made them feel more “balanced” or “happy” for short periods of time. This may appear, to an outsider, like an “instant” addiction. Other people build up a tolerance to drugs or alcohol through repeated use. Their brain adapts (neuroadaptation) to the substance and begins to function around it and depend on it, which may lead to addiction.⁵

Even neuroadaptation may alter a person’s gene expression over time. Genes responsible for the development of personality characteristics, mental health, and physical reactions to drugs and alcohol in a system (such as hangovers and impulsive behavior) can similarly influence (but not cause) neuroadaptation in the same way that other genes can influence (but not cause) “instant” dependence.⁶

Inheriting an Addiction vs. Inheriting Susceptibility

There truly is no “X marks the spot” in someone’s genetic fingerprint that will point to a future substance abuse problem. No one is born with an addiction. However, it would be much more accurate to say that addiction is certainly influenced by genes, and that makes all the difference in the world.⁴

The National Institute on Alcohol Abuse and Alcoholism states that genetics only account for about 50 percent of the chance of alcoholism.⁷ Further, people do not inherit addictions, they inherit a susceptibility to addictions. It is entirely possible that someone with alcoholic or drug-dependent parents may never have that problem of his own, especially if he avoids substance use or compulsive behaviors entirely. Likewise, a person who does not have a genetic predisposition towards substance abuse can still develop a drug or alcohol habit, and those changes may alter genetic expression over time.⁶

Genes, Substance Abuse and Mental Health

Some genes are directly tied to substance use and addiction, while other genes influence other factors that may eventually be associated with substance abuse, such as the following mental health conditions:

• Depression⁸
• Psychosis⁹
• Anxiety¹⁰
• Stress¹¹

National Institute on Drug Abuse states that pre-existing vulnerabilities in genetics can put an individual at risk for both an addiction and co-occurring mental health disorder or make them susceptible for developing a second disorder after an initial disorder develops.¹²

Know Your Family History

No gene (or one set of genes) will directly lead to a person abuse drugs or alcohol. Instead, genes determine the likelihood of such a problem developing, especially when other risk factors are taken into consideration.

The National Council on Alcoholism and Drug Dependence picks up on that train of thought, explaining that the role of genetics in substance abuse comes into play once a person actually starts abusing controlled substances. For that reason, NCADD declares as a fact that the “single most reliable indicator” of whether or not a person starts to take drugs or alcohol is family history.¹³

The conclusive research of the effects of a family history of alcoholism is in part why some people opt not to expose themselves to any risk and eschew alcohol totally. Such is the case with Joe Biden, the 47th Vice President of the United States, who explained his lifelong teetotalism as a result of “too many alcoholics in [his] family.”¹⁴

Changing the Substance Use Disorder Dialogue

Genes do matter when it comes to addiction, and understanding the ways they matter (and the ways they don’t) is critical to devising methods of education, treatment, and prevention of substance abuse disorders.

People once believed that there were one or two main causes behind addiction. Blame was usually placed on the addicted person, and they were often accused of being of weak moral character. Today, we know that there are many possible reasons why someone might develop a drinking problem. While genetic factors can account for roughly half the risk, the other half is spread out over a number of other concerns, including

• Gender: Men are more likely to become alcoholics than women, but women have more unique risk factors.
• Psychological factors: These include stress, depression and suicidal thoughts, among others.
• Emotional measures: People who are mentally or emotionally distressed may use alcohol or drugs to self-medicate. Likewise, people who have experienced trauma may be prone to substance use.
• Frequency: Men who consume alcohol more than 15 times a week, and women who consume alcohol more than 12 times a week will frequently develop a dependence.
• Social factors: The culture of alcohol may tip someone over the threshold between responsible alcohol use and problematic drinking.

Genetics is a complicated subject, and people not familiar with the basics might jump to one conclusion or another on how hereditary factors affect the likelihood of a drug or alcohol problem. While the full scope of the relationship may never be explicitly mapped out, we know enough today to say that having a parent with a substance abuse problem is not a guarantee of a future substance abuse problem, but we also know that having a parent with a substance abuse problem brings that danger much closer to home.

Are you struggling with an addiction in your life? If you or someone you care about has a problem with substance use, we are happy to help. Black Bear Lodge offers evidence-based treatment in a comfortable “home away from home” environment. Please call us today at 855-808-6212 to find out how we can help you.

Sources:

¹ Bagley, M. Genetics: The Study of Heredity. LiveScience.com. Feb 2013.

² What is a Gene? Genetics Home Reference. Apr 2015.

³ Genes and Addiction. University of Utah. Accessed 22 Jan. 2018.

⁴ Upregulation of Cannabinoid Type 1 Receptors in Dopamine D2 Receptor Knockout Mice is Reversed by Chronic Forced Ethanol Consumption.” Alcoholism: Clinical and Experimental Research. Jan 2011.

⁵ Koob, G. F., Simon, E. The Neurobiology of Addiction: Where We Have Been and Where We Are Going. Journal of Drug Issues. January 2009.

⁶ Ponomarev, I. Epigenetic Control of Gene Expression in the Alcoholic Brain. Alcohol Research: Current Reviews. 2013.

⁷ National Institute on Alcohol Abuse and Alcoholism. The Genetics of Alcoholism. 2013.

⁸ Major Depression and Genetics. Stanford School of Medicine. Accessed 22 Jan. 2018.

⁹ Psychosis Susceptibility Gene ZNF804A and Cognitive Performance in Schizophrenia. Archives of General Psychiatry. Jul 2010.

¹⁰ Vann, M. Is Anxiety Hereditary?” Everyday Health. Aug 2014.

¹¹ Bilkei-Gorzo, A., Rácz, I., et. al. A Common Genetic Predisposition to Stress Sensitivity and Stress-Induced Nicotine Craving.” Biological Psychiatry.Mar 2011.

¹² DrugFacts: Comorbidity: Addiction and Other Mental Disorders. National Institute on Drug Abuse. Mar 2011.

¹³ “Family History and Genetics.” National Council on Alcoholism and Drug Dependence. Sept 2008.

¹⁴ Riding the Rails with Amtrak Joe. The New York Times. Sept 2008.