People from all walks of life can develop a substance abuse disorder or addiction at some point; it is not dependent on your age, sex, or where you live. However, there are certain factors that increase the likelihood of one developing an addiction. Over the years researchers have proposed and investigated a multitude of risk factors. Whether these are environmental factors, family history, or undiagnosed mental disorders, all offer credible research and explanations as to why an individual may be more likely to develop the disorder compared to others.
Despite all credible research, we are still not 100% sure as to why some people become addicted and others do not. Why can some people smoke a cigarette every day for a year and stop without experiencing cravings? Whereas others can smoke a cigarette once a day for a week and the infamous nicotine dependence and addiction soon follow. Recent research has found a new substantial genetic link that suggests individuals can be genetically predisposed to developing an addiction.
With 275,896 adults living with a substance abuse disorder and contacting drug and alcohol related services in a single year, this new evidence has opened an exciting gateway for developing new treatment options for substance abuse and addiction.
Due to a lack of understanding of how biological processes are involved with substance abuse, treatment options have been limited. However, this new research has provided a foundation and opportunity for the creation of more substance abuse and addiction treatments.
Some addiction counsellors, however, take a different approach to the nature vs nurture argument. Paul Spanjar, an experienced addiction counsellor and director of the Providence Projects rehab clinic, warns against solely relying on genetic markers.
“Other factors need to be considered when determining the risk of addiction in an individual. We know this from decades of research, which shows a correlation between the home environment and later substance abuse issues. Just because an individual has a genetic exposure, does not always mean they develop issues later in life. This is true for other illnesses, both physical and mental”.
Genetics and Addiction
Our bodies are made up of billions of cells. Within each of these cells live around 20,000 to 25,000 genes – the shell of whom we are as individuals. Genes provide individualistic information that determines our biological and physical traits that we have inherited from our parents. Although 99.9% of genes are the same in most people, that 0.01% is accountable for three million differences that contribute to
variations in different people. These variations range from visible traits such as eye or hair colour, height, or even the size of your nose to invisible traits, such as the risk of developing certain diseases such as stroke, diabetes, and addiction.
There are some diseases that are caused by changes within one single gene, also known as a mutation. Studying these mutations has allowed medical researchers to evaluate an individual’s risk of developing diseases later in life. However, many diseases are seriously complex and are caused by variations in several different genes. Addiction is one of these diseases.
However, recent advances in technologies have allowed researchers to find connections between known genes and different disorders. Genome-wide association studies (GWAS) involves identifying genetic variations across the genetic make-up of different individuals to establish specific genes that are associated with complex human traits, like addiction.
Cannabis is one of the most used psychoactive substances worldwide and holds a very high risk for dependence. In fact, in the UK 2.6 million people were recorded to have used the drug in a single year and it is believed that 30% of users represent problematic use, including addiction. Researchers wanted to investigate whether this popular choice of drug had a strong genetic component. A GWAS study conducted
in 2017 found that low levels of a specific gene, called CHRNA2, in an area of the brain called the cerebellum, were found to be associated with cannabis use disorder. The findings provide the medical world with a specific target that should be focused on in prevention strategies, therapies, and medications.
Genome-Wide Association Studies – Linking Genetics and Addiction
Whilst GWAS allows researchers to identify specific regions in our genetic make-up that play roles in different traits, as compared to those who do not display these traits. It does not tell us how these genes affect said trait. This means that what actually happens biologically remains pretty much unknown – until now.
UNC School of Medicine researchers, led by assistant professor of genetics and member of the Neuroscience Centre Hyejung Won, have developed HI-C coupled MAGMA (H-MAGMA), a new computational tool to help make sense of GWAS results. Won’s lab applied H-MAGMA to a series of GWAS findings that were related to nicotine dependence, heavy smoking, problematic alcohol use, and heavy drinking patterns to try and identify genes that were associated with each of these different traits.
The research team set out to determine if the genes that were associated with cigarette smoking and alcohol use could reveal genetics that were underlying other general addictive behaviours. They hoped this could then be extended to other forms of substance abuse and addiction.
The researchers found that these genes associated with smoking and alcohol addiction were overrepresented in specific neurons. Neurons are cells found within the brain that send chemical signals to communicate information between different areas of the brain, as well as between the rest of the nervous system and the brain. They also found that the genes underlying cigarette smoking were connected to pain perception and our responses to food as well as abuse of alternative drugs, like cocaine. Genes that were linked to alcohol addiction were related to learning, stress, and the abuse of drugs such as morphine.
Understanding the lack of alternative treatment options for substance use disorder, the lab team attempted to identify new potential treatments for substance abuse. They conducted an analysis of an already established drug database and found that mood stabilisers, such as antipsychotics, could possibly provide relief for those living with a substance abuse disorder.
What Does This Mean?
The findings of the research provide exciting opportunities for medical professionals to focus on creating more alternative and effective treatments to address substance abuse disorders and drug dependencies. The more we learn about our biological makeup and our underlying genetic differences, the better chance we have to develop centred and direct therapies. These can be individualised and customised for each patient, to aid the millions of people living worldwide with a substance abuse disorder.
