Scientists examined the genetic data of over a million people and found genes that are often inherited in addiction disorders, regardless of the substance being used.
This large-scale study could help find new ways to treat different substance use disorders, even for those who have more than one.
The findings also confirm the importance of the dopamine system in addiction.
The study, published in Nature Mental Health, was led by researchers from Washington University in St. Louis and had more than 150 coauthors from around the world.
Various institutions supported the study, including the National Institute on Drug Abuse, the National Institute on Alcohol Abuse and Alcoholism, and the National Institute of Mental Health.
Until now, there has been limited knowledge of the genetic foundations of addiction.
Most studies have focused on individual substances rather than addiction as a whole.
Through genetic studies, researchers aim to understand better the factors that can either protect or predispose someone to substance use disorders, ultimately helping with prevention efforts and enabling people to make informed decisions about drug use.
The Scope of Substance Use Disorder
In 2021, over 46 million people in the United States aged 12 or older had at least one substance use disorder, but only 6.3% received treatment.
Drug use and addiction pose a serious public health crisis with significant costs to families, communities, and society.
People who use drugs are now facing a more dangerous situation, as the drug supply is increasingly contaminated with fentanyl, a very potent synthetic opioid.
In 2021, about 107,000 people died from drug overdoses, and 37% of these deaths involved the use of both opioids and stimulant drugs simultaneously.
Drug use and addiction are major public health problems, causing social, emotional, and financial harm to families, communities, and society.
Substance use disorders can be passed down through families and are affected by many genes and environmental factors.
Using Genomics to Find More Effective Ways of Treating Addiction
In recent years, a new method called genome-wide association has been developed to help identify specific genes involved in certain disorders.
This technique looks at the entire genetic makeup of a person, searching for small genetic differences, known as single-nucleotide polymorphisms (SNPs), that are linked to the same illness or condition in multiple people.
In this study, researchers used this method to find parts of the genetic code linked to addiction risk and the risk of specific substance use disorders, such as alcohol, nicotine, cannabis, and opioid use disorders.
They studied over a million people with European ancestry and over 92,000 people with African ancestry to make these discoveries.
Using genomics, or the study of our genetic information, researchers can better prioritize existing medications for further investigation and improve the chances of finding new treatments. It’s important to include diverse populations in genetic studies and involve people from communities that have been historically underrepresented in medical research, said Alexander Hatoum, Ph.D., the study’s lead author.
Genetic Pattern Findings for Those With European Ancestry
The research team identified several genetic patterns related to addiction. The European ancestry sample found 19 SNPs (small genetic differences) linked to general addiction risk and 47 SNPs related to specific substance use disorders.
The most significant gene signals were connected to areas in our genetic code that control dopamine signaling regulation. This suggests that variations in how dopamine signaling is regulated, rather than the signaling itself, are key to addiction risk.
This genetic pattern was a better predictor for having two or more substance use disorders simultaneously, compared to other genetic predictors.
It also predicted a higher risk of mental and physical health issues, such as psychiatric disorders, suicidal behavior, respiratory disease, heart disease, and chronic pain.
This genetic pattern was a better predictor for having two or more substance use disorders simultaneously compared to other genetic predictors.
It also predicted a higher risk of mental and physical health issues, such as psychiatric disorders, suicidal behavior, respiratory disease, heart disease, and chronic pain.
In 9 or 10-year-old children with no experience of substance use, these genes were linked to their parent’s substance use and externalizing behavior or acting out.
“Substance use disorders and mental disorders often happen together, and we know that the most effective treatments help people deal with both issues simultaneously.
The shared genetic factors between substance use and mental disorders found in this study highlight the importance of considering these disorders together,” said NIMH Director Joshua A. Gordon, M.D., Ph.D.
Findings for Those with African Ancestry
In the African ancestry group, the study found one small genetic difference (SNP) linked to general addiction risk and one specific to alcohol use disorder risk.
According to Hatoum and co-authors, the limited findings in this group emphasize the ongoing issue of the unequal representation of global populations in research data, which needs to be addressed to ensure reliable and accurate results.
Including data from various ancestral groups in this study should not be used to assign or label different genetic risks for substance use disorder to specific populations.
As genetic information is used to understand health and inequalities better, it’s crucial to collect diverse and inclusive data.
NIDA and other NIH institutes supported a recent National Academies of Sciences, Engineering, and Medicine report about responsibly using and interpreting population-level genomic data.
Specific Substance Use Diagnoses Still Matter
While Hatoum and his team found a genetic pattern that shows a general risk for addiction, they emphasize that specific substance use diagnoses still matter.
“This study confirms earlier findings of alcohol-specific risk factors and does so in a much larger and more diverse group of people,” said NIAAA Director George F.
Koob, Ph.D. “Discovering shared genetic risk factors across different substance use disorders helps us understand the underlying mechanisms of these disorders and their connections to other mental health conditions.
The findings on alcohol-specific and common addiction-related risk factors strongly support personalized prevention and treatment approaches.”
Sources
[1] New NIH study reveals shared genetic markers underlying substance use disorders
