Is Addiction Genetic?
March 15th, 2017
If you have a family member with addiction, especially a person close to you such as a parent, you may be fearful of developing an addiction. The truth is, addiction is a very complicated, multifaceted disorder, the exact circumstances of which vary from person to person. In order to better grasp this, it is imperative that we seek to understand the spectrum of risk factors that are associated with it, helping to protect ourselves from the many harms that addiction carries.
What Are Genetics?
Genetics are powerful and complex codes going into the makeup of every living thing on the face of planet Earth. Each of these organisms has a genetic code that is unique to their species, granting them the specific characteristics that make them different. Even then, human to human, our genetic codes differentiate who we are from the next person, however, sometimes they carry risk factors to our descendants.
In basic terms, every nucleus-containing cell is home to certain genes that are replicas of every other gene within the same body, each of which carry these specific DNA codes. A person’s DNA is a code, or set of instructions, carried within a larger genetic component called a chromosome; this code is a blueprint for building and creating our genetic makeup. In terms of inheritance, these genes are what are passed parent to offspring, thus passing on certain genetic trends or weaknesses, such as addiction.
When a gene creates a specific change, such as hair or eye color, it is due to certain variations. These variations are passed directly from your parents, as you receive 23 chromosomes from each parent, a total of 46, when you are conceived. It is these genetic variations that are responsible for the likelihood that certain changes will occur. In the case of addiction, it is not a singular variation that is responsible, rather it is more complex, and scientists believe there are several. So, while it is true that certain genetic variations may occur that can enhance your predisposition to certain types of addiction, they do not ensure a 100 percent chance that these addictions will actually arise.
Do Genetics Factor Into Addiction?
You would think this would be a simple answer, however, the answer does not fall into the form of a simple “yes” or “no,” rather, it requires an explanation to develop a better understanding of the role that genetics has within addiction. Because yes, in part, addiction may be caused from genetics, the operative word being “may.” The University of Utah’s Genetic Science Learning Center offers a powerful directive on this subject, asserting that “Susceptibility Does Not Mean Inevitability.”
The tendency towards addiction is complex and dependent on numerous factors even within a person’s genetics. The National Institute on Alcohol Abuse and Alcoholism, explains, noting that “Unlike for some other diseases, there is no single gene that determines whether you will develop a problem with alcohol; instead, many genes influence your risk for developing alcoholism, each of which only has a small impact.”
Just because a person has a genetic predisposition does not mean that they will develop addiction, or even patterns of abuse. It simply means that their risk factor is higher and that they should be extra careful in developing both a greater awareness and protective factors within their life. This is important to keep close to heart if you feel that you may have a genetic risk factor.
The National Institute for Drug Abuse tells us that based on numerous studies on various degrees of siblinghood (typical siblings, adoptees, and fraternal or identical twins) up to 50 percent of a person’s risk towards developing an addiction is linked to genetics. Within this statistic, the percentage of risk may also vary according to the drug of abuse, one study tells us, noting that “Heritabilities of addictive disorders range from 0.39 for hallucinogens to 0.72 for cocaine.”
Along with genetics, there are other risk factors, psychological, cultural or environmental. Within these broadened categories are other more specific factors, including family issues, relationships, community, financial standing, lack of economic opportunity and instances of trauma, among others.
Considering The Impact That Genetics Has Upon Addiction
You may be surprised to know that our brains contain receptor sites for nicotine cannabinoids, and opioids. Even more surprising is that we naturally create nicotine, cannabinoid and opioid substances within our brains, specifically endogenous versions, or “keys.” What is the impact of this? Due to the fact that our bodies are naturally receptive to the effects of these substances, our brains are quick to adhere to the illicit chemical (manmade or other) versions of these drugs that we put into our systems. Once in our systems, these drugs flood the receptor sites; as use increases, our bodies fail to produce important neurotransmitters, such as dopamine, to the extent that our body craves the illicit drug for the purpose of continuing to create dopamine.
Dopamine is a neurotransmitter that is consistently linked to addiction. It is elemental within our brains for creating feelings of pleasure and reward. When something offers us this reward, we want to revisit the feeling by doing it again, in these cases by using the substance of abuse. Subsequently, certain individuals have genetic variations that change the way the chemical processes of this neurotransmitter function within your brain, thus changing a person’s predisposition to compulsively using certain addictive substances.
The Genetic Science Learning Center reports that “The A1 allele of the dopamine receptor gene DRD2 is more common in people addicted to alcohol or cocaine.” They also report on the possibility of another neurotransmitter that may also impact individuals concerned with this risk of cocaine or alcohol abuse, as shown by research on mice. They found that test subjects without a serotonin receptor gene called Htr1b have a greater interest or pull towards these substances.
Our bodies are regulated by an internal clock called a circadian rhythm, which actually has molecular components within our brain that are expressed in genetic ways, called circadian genes, or the clock gene function. One research report, “Circadian rhythms and addiction: Mechanistic insights and future directions,” illustrated that when this function was disrupted, a person may be at greater risk of developing an addiction. In example, researchers found that a variation of the PER2 gene made people more susceptible to a cocaine addiction.
They also determined that other disturbances to the circadian system altered the limbic function, which in turn affected a person’s drug-seeking behaviors, and thusly the reward-related pathways. Again, reward seeking is interconnected with dopamine; changes within the functioning of this neurotransmitter were also witnessed within the circadian system. The report outlines that these “clock gene mutations in the context of reward are also associated with disruptions in dopamine transmission within the VTA” or ventral tegmental area of the brain, a group of neurons that is foundational within our brain’s “reward circuit.” These changes “increase the vulnerability to the rewarding properties of drugs.” The study also notes that the genetic mutations responsible for these circadian changes may also adversely affect not only addiction, but the extent of impact for withdrawal and risk of relapse.
Genetic impact may also vary dependent on the point of use within a person’s life, reports research referencing The Virginia Twin Study. These findings focused on cannabis, nicotine and alcohol, and determined that the effects of genetic factors were less in early adolescence, where instead the driving pressures were due to society and family. However, the impact of genetic factors did become more apparent, peaking in “young and middle adulthood,” then decreasing as a person aged. This is especially frightening when you consider the fact that a person’s risk of addiction increases, especially for alcohol, if they began using at these ages.
How Do Genetics Affect Alcohol Addiction
There has been much research into the role of genetics within alcohol addiction, leading to finds that show multiple genetic impacts on this risk.
When we consume alcohol, our bodies need a way to process it, a function that is overseen by various genes. These genes produce two enzymes, alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), that break alcohol down so that the toxins can leave your body. Certain variations of the genes responsible for these components may result in a person not being able to effectively process alcohol, which can lead to a build up of a toxic byproduct of alcohol called acetaldehyde. When these levels become too high, a person will begin to feel unwell. Scientists have found that people with these genetic variations, including an estimated 36 percent of East Asians, are less apt to have an alcohol addiction, due to the fact they have a tendency to drink less as a means to avoid these uncomfortable effects.
Research into γ-aminobutyric acid (GABA), a primary inhibitory neurotransmitter within our brains, has offered even more insight. A National Institute for Alcohol Abuse and Alcoholism publication reports that findings have linked this neurotransmitter to “many of the behavioral effects of alcohol, including motor incoordination, anxiety reduction (i.e., anxiolysis), sedation, withdrawal signs, and preference for alcohol.” Scientists focused specifically on the GABAA receptor, a receptor that has also been implicated in various other addictions. What they found is that chromosome four within this receptor contains a gene GABRA2 that is linked to alcohol dependence. This is because these individuals may have a greater responsiveness to alcohol’s effects, and consider the way it makes them feel more appealing or rewarding in comparison to other individuals.
Further investigation into GABRA2 revealed a link between alcohol addiction and co-occurring drug addiction. Variations in GABRA2 are also associated with electrophysiological characteristics which are most evident in individuals who suffer from both an alcohol and drug addiction.
Another genetic influence which is less understood than the others revolves around certain genes that are involved in regulating a person’s immune system. You may wonder how the immune system could dictate addiction. What happens is that when the immune system is active, perhaps overly so, the signals for your immune response within your brain get in the way of the ones responsible for decision making, thus partially circumventing a person’s ability to wisely regulate their behavior.
Going back to the gene-related research on the connection between the circadian rhythm and addiction, we find that there is also a direct impact on a person’s risk of alcohol addiction, specifically that “Circadian desynchrony itself may be a risk factor for alcoholism.” Findings also exhibit how these alterations may affect a person’s mood, which we know often results in a person turning to alcohol as a tool for emotional regulation or self-medication, two things that may also lead to addiction. They suggest these circadian gene irregularities increase the risk of drinking alcohol by possibly aiding in the development of “compulsive alcohol drinking in adolescents and the maintenance of heavy alcohol drinking in adults.” A multitude of research has shown that those who start drinking heavily in adolescence are at a greater risk of having an addiction later in life.
A study created in conjunction between the Washington University School of Medicine in St. Louis and the Queensland Institute of Medical Research in Brisbane, Australia found that there appears to be a correlation between a person’s genetics and the probability that they will experience an alcohol-related blackout, a condition that is more common in those who are alcohol-dependent. The study’s authors note that this relationship may be due to the fact that certain individuals have “less efficient variants of genes involved in metabolizing alcohol,” as well as effects to genes that are involved in the formation of memories.
Interestingly enough, a person’s genetic makeup may also influence how they respond to treatment. In terms of alcohol addiction, research has determined that there is a certain gene variation responsible for determining how the drug naltrexone works towards reducing drinking in patients that are alcohol dependent.
Find Out How To Protect Yourself Against This Risk
If you suspect that you or your family member has a genetic predisposition to an alcohol addiction, and you’re interested in learning more about the steps you can take towards protecting yourself from this risk, contact us at The Treehouse today. We can help you to better understand how to implement positive and protective factors to bolster your protection against alcohol abuse and addiction.
Genetic Science Learning Center — Genes and Addiction
The American Society of Human Genetics — Six Things Everyone Should Know About Genetics
National Institute on Alcohol Abuse and Alcoholism — The Genetics of Alcohol and Other Drug Dependence
National Institute on Alcohol Abuse and Alcoholism — The Genetics of Alcoholism
U.S. National Library of Medicine — Circadian rhythms and addiction: Mechanistic insights and future directions