The Role of Genetics in Addiction: Understanding the Science

When scientists look for “addiction genes,” what they’re really looking for are biological differences that may make people more or less susceptible to addiction. 

Everyone reacts differently to drugs and medications. Maybe you have experienced it too. Suppose you take a medicine and it works well. However, the same medication may not work for one friend and make another friend feel sick. Such differences are often caused by genetic differences. 

When scientists look for genes associated with addiction, they look for genetic variations associated with these types of responses. Vulnerable people may have a strong preference for certain substances. Or you may experience extreme withdrawal symptoms if you try to quit. On the other hand, people who do not experience pleasure from drugs that intoxicate others are equally vulnerable. 

When addiction runs in families: 

Substance use disorders often run in families. That’s because it has an inherited component, meaning it can be passed from parent to child via genes. Therefore, your family history may provide clues as to whether you are susceptible to addiction. For example, if someone in your immediate family is affected, that’s a clue to pay special attention. 

Researchers also use family history. They compare DNA sequences of family members to identify genes involved in addiction. 

First, he divides the family into two groups: 

The affected group and the unaffected group. Researchers then look for segments of chromosomes that are more common in affected people than in unaffected people. They narrow down the segments to specific genes for further study. Because humans lead complex and diverse lives, detailed studies are often conducted using animals in controlled laboratory settings. Many genes influence addiction. Scientists will never be able to discover just her one genetic change that causes addiction. Like most other illnesses, substance use disorders have complex characteristics. In addition to multiple genetic mutations, it is also influenced by environmental factors. 

Every person inherits a unique combination of genetic mutations. People with substance use disorders may have a variety of underlying genetic causes. And people who share a particular high-risk genetic mutation may or may not have the trait. 

Although it is difficult to find the exact genetic cause, research shows that genes influence substance use. Scientists estimate from careful research that a person’s genetic factors account for 40 to 60% of her risk. 

Discovery of addiction genes: 

Many genes involved in addiction have been studied in animal models, particularly mice. Just like us, mice and other animals have reward pathways. It has very similar functions to us, and many of its underlying genes are similar. 

As in the example above, genes potentially associated with addiction are sometimes discovered in people. Next, we will investigate in detail using animal models. Other genes are first discovered in animal models and then confirmed in humans. 

One of the big things we’ve certainly learned is that different biological processes influence the risk of addiction. And each process has many underlying genes. 

Here are just a few examples of genes that influence addiction risk.

A protective mutation in the alcohol dehydrogenase 2 gene (ALDH22) encodes a protein that cannot break down alcohol as normal. People with ALDH22 experience nausea, facial flushing, headaches, and increased heart rate when they drink alcohol. Mice that produce more protein from the Mpdz gene experience less severe withdrawal symptoms from sedative-hypnotics such as alcohol and barbiturates.

The A1 type (allele) of the dopamine receptor gene DRD2 is commonly found in alcohol, cocaine, and opioid addicts. This variation can influence how drugs affect reward pathways. Mice with specific mutations in the Per1 and Per2 genes drink much more alcohol than normal, especially under stress. People with certain She Per1 and Per2 variations, especially those in her teens, also seem more likely to follow this pattern.

Drosophila melanogaster does not have the moodiness gene and is more sensitive to cocaine. Moody encodes a protein necessary for a healthy blood-brain barrier. 

Gene PSD-95 encodes a protein involved in learning and memory. Mice classified as “hypersensitive” to cocaine produce about half as much protein as normal mice. 

Mutations in the mu-opioid receptor gene (OPRM1) alter the amount of protein produced. Certain mutations are common in people with opioid use disorder. Some increase the risk of alcohol dependence. 

A person who has two copies of a certain type of gene, CHRNA5, is twice as likely to become addicted to nicotine compared to a person who has two copies of another allele. CHRNA5 encodes a protein that helps cells sense nicotine. In rats, the lack of mGluR2 receptors confers additional risk and protection. Rats are less affected by cocaine. They tend not to care if they have to work to get their medicine. But when cocaine is easily available, it takes a lot of it to feel its effects. 

From genes to treatments: 

Finding the genes involved in addiction is a good first step to finding a solution. Understanding how genes cause biological differences may lead to improved treatments for substance use disorders. 

Each newly discovered addiction-related gene is a potential “drug target.” Researchers can focus on a gene product (protein) and develop drugs that alter its activity. The goal is to correct the signals or pathways and restore proper brain function. 

Gene therapy is also being developed to treat addiction. One gene therapy being tested in mice produces antibodies that capture methamphetamine, blocking it from reaching the brain. In another experiment, mice transplanted with genetically modified skin cells produce an enzyme that breaks down cocaine.

As we learn more about how drugs work differently in different people, genetic testing may help with treatment. In the long term, it could be used to predict which treatments will be most effective based on an individual’s genetic profile.

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