Is Alcoholism Genetic?

Check out this answer from Consensus:

The research indicates that alcoholism has a significant genetic component, with heritability estimates suggesting that genetic factors account for 40% to 60% of the risk. Specific genes related to alcohol metabolism and neurobiological pathways have been identified, and the interaction between genetic predisposition and environmental factors is crucial. While the genetic architecture of alcoholism is complex, involving many genes with small effects, ongoing research continues to uncover the genetic underpinnings of this disorder.

The question of whether alcoholism is genetic has been a subject of extensive research. Numerous studies have investigated the genetic underpinnings of alcoholism, examining the heritability, specific genes involved, and the interaction between genetic and environmental factors.

Key Insights

• Heritability Estimates:
  • Alcoholism has substantial heritability, with estimates ranging from 40% to 60%1 6 7 9.
• Genetic Influence on Alcohol Metabolism:
  • Genes encoding alcohol-metabolizing enzymes, such as ADH4, have shown robust associations with alcoholism4 6 9.
• Candidate Genes and Genetic Variants:
  • Specific genes like GABRA2, CHRM2, and CRHR1 have been identified as contributing to the risk of alcoholism, with some variants showing stronger associations in individuals exposed to early-life trauma4 6 7.
• Familial and Twin Studies:
  • Family, twin, and adoption studies consistently suggest that alcoholism is familial, with a significant proportion attributed to genetic factors1 3 10.
• Gene-Environment Interactions:
  • The interaction between genetic predisposition and environmental factors, such as stress and trauma, plays a crucial role in the development of alcoholism4 7 8.
• Neurobiological Pathways:
  • Genetic variations affecting neurobiological pathways, including those related to stress response, reward systems, and behavioral control, are implicated in alcoholism1 4 7 8.
• Complex Genetic Architecture:
  • The genetic risk for alcoholism is likely due to common variants in many genes, each with a small effect, rather than a few genes with large effects4 8.

Is alcoholism genetic?

Brien Riley has answered Likely

An expert from Virginia Commonwealth University in Psychology, Genetics

First, it is extremely important to distinguish between genetic causation and genetic influence. Classical, Mendelian genetic disorders (Cystic Fibrosis, Huntington’s, Achondroplasia, etc, etc) and even some early onset forms of common disorders (early onset Alzheimer’s or early onset familial breast cancer, eg) are caused by mutations in a single gene meaning that there is a 1:1 correspondence between carrying the mutation (or mutations, in the case of a recessive disorder) and having the condition. In such cases, it is not terribly inaccurate to talk about “the gene for condition X”. In the case of common traits or disorders, however, a very different picture emerges. For most common human traits (schizophrenia, addiction, most neurological disorders, most cancers, most diabetes, most cardiovascular disease, and on and on), there are no individuals known where these common traits are “caused” by a single mutation in a single gene. On the other hand, genetic risk for these traits has been repeatedly demonstrated. For example, family studies show that the baseline rate of schizophrenia in the general population (and in the first degree relatives of control subjects) is in the range of 0.5-1%, while the rate in the first degree relatives of people with schizophrenia is ~10 times this baseline rate. This excess risk cannot be attributed to shared environment, and twin studies suggest that as much as 80% of schizophrenia risk may be heritable. This collective evidence leads to the current understanding that, while Mendelian traits truly are genetically caused or determined, common traits are genetically influenced but critically not genetically determined. This picture (and all current data) has led to the current widely-accepted view of common human traits, including alcohol dependence: 1. These traits are polygenic, meaning that variation in many genes can increase (and probably also decrease) risk. 2. These traits are multifactorial, meaning that environmental or other non-genetic risks are also important (often more important than genetic factors). In the case of addictions, this is especially clear: exposure to the substance (a non-genetic, environmental exposure) is absolutely required for an individual to manifest their genetic risk: someone may have extremely high genetic risk for alcoholism, but if their life experience has led them to decide never to drink, they will never experience the critical exposure and will never manifest that genetic risk. 3. Individual genetic variants associated with common traits have very small effect sizes, meaning an individual DNA sequence variation makes a small contribution to total trait risk. This observation is highly consistent with the lack of any cases attributable to the effect of a single mutation, suggesting that single gene causes of these traits either do not exist at all, or are so rare that they have little relevance for understanding a trait like alcoholism in the general population. 4. These traits show highly variable estimates of heritability, suggesting wide variation in the relative importance of genetic and non-genetic influences on risk. Major depression has estimated heritability of ~40%, alcohol dependence of ~50%, schizophrenia of ~80%. Sample sizes in excess of 150K subjects are currently being studied for schizophrenia genetic risk, with ~200 loci in the genome robustly associated with risk. By contrast, sample sizes for depression and alcohol dependence are in the 20-40K range, probably still too small to robustly identify the genes influencing risk. With further increases in the size of available samples, robust results should emerge from depression and alcohol dependence, as well. With all that said, there are believable reports beginning to emerge implicating specific genes in alcoholism risk. For example this paper Mol Psychiatry. 2014 Jan;19(1):41-9. doi: 10.1038/mp.2013.145. Epub 2013 Oct 29. Genome-wide association study of alcohol dependence:significant findings in African- and European-Americans including novel risk loci. Gelernter J1, Kranzler HR2, Sherva R3, Almasy L4, Koesterer R3, Smith AH5, Anton R6, Preuss UW7, Ridinger M8, Rujescu D7, Wodarz N8, Zill P9, Zhao H10, Farrer LA11. https://www.nature.com/articles/mp2013145 Two independent reports have now implicated variation in or around the alcohol dehydrogenase 1b (ADH1B) gene, and given the importance of this enzyme in ethanol processing, it’s involvement makes intuitive sense (even if these results are somewhat disappointing because they did not identify new candidates – ADH1B is a long-standing candidate gene for alcohol-related traits). However, this signal does fit with another widely-held set of expectations, that dependence risk may be altered by three very different kinds of genes. First, we expect that some genes may alter dependence risk for a specific substance (variation in endogenous opioid receptors in opioid dependence, or in endogenous cannabinoid receptors in cannabis dependence, or in the genes encoding enzymes metabolizing ethanol in alcohol dependence). Second, we also expect that some genes may have shared effects across dependence on different substances (or even behaviors) because they affect the function of brain reward circuitry implicated in substance use and other pathological behaviors. Finally, we expect that there will be overlap between the genes that influence substance use and dependence and those that influence personality traits like internalizing and externalizing behaviors, which are strongly associated with risk. So, the final answer to your question (Is alcoholism genetic?) is thus somewhat nuanced: 1. The answer is yes, partly but not completely – only about 50% of the risk appears to be genetic. 2. There is currently no evidence to support a statement like “Gene X is the gene for alcoholism” (and in my opinion, there never will be any such evidence, for the reasons laid out above). Need to get the memo out to the science journalists and bloggers on this one. 3. Ongoing studies in larger samples will identify additional candidate genes influencing risk, as we have observed in many other traits. Study size (and study power) are absolutely critical to progress in all common, complex traits. 4. Some of these genes may not be specific to alcohol, but might predispose to a broader substance dependence risk through influence on the function of reward circuitry or susceptible personality types.

Is alcoholism genetic?

Ian Hamilton has answered Uncertain

An expert from University of York in Drug Use, Addiction, Mental Health

Although there has been a significant amount of research investigating a genetic link to alcohol dependence the science points to a blend of nature and nurture. It is difficult to distinguish the impact that parenting and genetics have, undoubtly environmental factors are significant. We also need to think about what we do with information suggesting there is a genetic component ?

Is alcoholism genetic?

Matt Parker has answered Likely

An expert from University of Portsmouth in Neuroscience, Alcohol Use, Neurodegenerative Disease

The first thing to say is that everything is genetic to a point! We are biological organisms, so to some extent, our genes will play a role in everything. An example of this in relation to alcohol is that is metabolised (broken down) in our bodies by an enzyme called ‘alcohol dehydrogenase’. Scientists have established that people with a particular variant in this gene that causes alcohol to be broken down less effectively are far less likely to drink heavily – this is likely because they would feel the effects of alcohol much stronger than others. These people almost never become alcoholics either! Probably because they don’t really like the effects of drinking a lot, and therefore don’t get the chance to drink regularly enough to become addicted.

Addiction is not just a physical process, however; it is also based on psychological (eg your personality) and environmental (eg family/friends/economic situation) issues. In this sense, the extent to which alcoholism is genetic is a matter of debate in the scientific literature. 

Is alcoholism genetic?

Alasdair MacKenzie has answered Near Certain

An expert from University of Aberdeen in Genetics, Mental Health, Cannabis, Anxiety

There is a great deal of evidence to suggest that alcohol abuse has a strong genetic component with both human studies and animal models backing this up.

There seems to be a number of different stages in the development of alcoholism rather than just one single cause. One of the most important is our ability to metabolise alcohol. Thus, in genetic studies, the gene that scores most highly in relation to alcohol addiction is alcohol dehydrogenase, which metabolises alcohol.

The next factor in alcohol abuse is the decision by an individual to preferentially drink alcohol in preference to a non-alcoholic drink. This aspect is controlled by an area of the brain called the hypothalamus which governs appetite and food choices. We have found that our genetic switch, in addition to controlling anxiety, also controls the decision to drink alcohol in mice. Intriguingly, this has also been mirrored in human populations where genetic changes in the switch are linked to increased alcohol intake in anxious men suggesting a mechanism linking anxiety and alcohol intake which is most obvious in males. Our identification of this switch also suggests the role of an environmentally modulated epigenetic component that we are currently exploring. Thus, gene switches; or enhancers, may represent the “battlegrounds” where our genetics fight with environmental cues to decide on who we become as individuals.

The final, and least well understood, factor in alcoholism is the reward pathways of the brain which govern all addictive behaviours. These pathways involve the pleasure centres of the brain such as the nucleus accumbens which, in many people, become over-activated by stimuli such as alcohol intake Together, all these factors form the basis of alcoholism.

Is alcoholism genetic?

David Eccles has answered Likely

An expert from Malaghan Institute of Medical Research in Genetics, Genomics, Bioinformatics, Biostatistics, Data Science

Answering “Is X genetic” questions is difficult. We are created and changed both by what we are (i.e. our genes) and what we experience (i.e. our environment). Every trait we have has an environmental component and a genetic component to its appearance and its variation.

To drill deeper into that needs a lot of conditional statements. Genetics and environment interact with each other and change us in ways that can’t be predicted by a study of one or the other on its own. The environment we live in can both hide the way in which we are changed by our genes, and make those changes more glaringly obvious. As an example, there are genes that have a strong influence on your ability to see different colours as different (i.e. colour blindness). If you were blinded in an accident, then those genes don’t matter. If your job depends on your ability to tell colours apart (e.g. a clothing designer), then the impact of those genes is made a lot more obvious.

In addition, there’s not really a single thing that can be called “alcoholism”. Alcoholism refers to an entire class of psychosocial disorders that are based upon the misuse of alcohol. It is tempting to try to place patients into distinct groups based on what type of alcoholism they have, but that approach does not seem to fit the complex nature of the disease. A better viewpoint may be to see the two component behaviours (abuse and dependence) as two interacting dimensions of alcoholism (with the possibility of more unknown dimensions being present), with a continuum of severity possible for both types.

That said, we know that there are variants in different regions of the genome that alter how alcohol is processed by our bodies, and this variation can alter how tolerant people are to alcohol. I looked at one of these regions, the alcohol dehydrogenase (ADH) gene cluster on chromosome 4, to follow up research carried out by Geoff Chambers in identifying a variant in ADH1B (rs1229984) that appeared to be conditionally associated with alcohol dependence in some human populations. What I discovered was that there were potentially multiple interacting genetic variants within that gene cluster, which makes it very difficult to determine the precise link between genetic variants and a specific facet of alcoholism.

For more details, see Chapter 2 of my PhD thesis.

Is alcoholism genetic?

Danielle Dick has answered Near Certain

An expert from Virginia Commonwealth University in Alcohol Use, Genetics

It is widely accepted by researchers that alcohol use disorders are influenced by genetic factors; we are not all equally at risk. The heritability of alcoholism is about 50%, which means that about half of what contributes to the differences between how likely people are to develop problems is differences in their DNA sequences. The other half is due to differences in their environments. For people who are carrying genetic risk factors some environments can be particularly risky (parents who don’t monitor their children in adolescents, deviant peers, stressful events) and make it more likely they will develop problems, while other environments are protective and reduce the chance that at risk individuals will develop problems. In short, genes aren’t destiny.

Here’s a short blog where you can get more information: http://cobe.vcu.edu/5-things-we-know-about-addiction-and-2-we-dont/