Do genetic markers hold the key to understanding substance use disorders?

By Carol Nathan | Medically reviewed by Amanda Zeglis, DO, MBA
Published September 5, 2023

Key Takeaways

  • In 2021, more than 46 million people in the United States had at least one substance use disorder, but only 6.3% had received treatment. 

  • An NIH study reported that addiction is associated with inherited genes. These genes were also associated with the regulation of dopamine signaling, confirming the role of dopamine in addiction.

  • These findings can potentially lead to biomarker development and new addiction treatment targets.

Drug abuse and addiction are a public health crisis that involve high social, emotional, and financial costs to families and society at large. There is also significant stigma surrounding addiction, despite increasing evidence that addiction is a disease that is preventable and treatable—much like heart disease, for example.[] 

But a 2023 NIH study of more than 1 million individuals published in Nature Mental Health found the presence of specific genes associated with addiction. These genes were found to be commonly inherited, regardless of the type of substance use disorder.[]

The genetic science involved

Prior research has established that substance use disorders are heritable and can involve multiple genes. A process called genome-wide association has been developed to identify genetic variations in genomes. 

These variations, called single-nucleotide polymorphisms (SNPs), can be linked with the same disease, disorder, condition, or behavior among multiple people.

The NIH study used this method to look for genes associated with general addiction overall, along with specific addiction risks, including alcohol, nicotine, cannabis, and opioids. 

The sample size was large, with 1,025,550 individuals of European ancestry and 92,630 individuals of African ancestry. The goal was to include globally represented populations. 

The researchers found 19 independent SNPs that were strongly associated with general addiction risk, and 47 SNPs for specific substances in the European ancestry sample. Many of the genes co-occurred among addiction and mental disorders, indicating the link in these conditions. 

The researchers note that the findings from the African ancestry portion of the cohort were not useful, most likely due to the small sample size compared with the European cohort.[] 

The researchers noted that, taken together, the specific substance risk variants combined with the general addiction-related variants provide strong support for individualized prevention and treatment. These findings can potentially lead to more effective prevention and treatments for substance use disorders. 

The SNPs identified in the study were also associated with dopamine signals, confirming the role of dopamine in addiction. This finding supports the need for research into biomarker development and treatment targets.[]

This international study was supported by several federal agencies, including the National Institute on Drug Abuse (NIDA), the National Institute on Alcohol Abuse and Alcoholism (NIAAA), the National Institute of Mental Health (NIMH), the Eunice Kennedy Shriver National Institute of Child Health and Human Development, and the National Institute on Aging.

Scope of the addiction problem

This research is important, because according to the NIH, more than 46 million people in the US had at least one substance use disorder in 2021, but only 6.3% had received treatment. The same year, approximately 107,000 people died of drug overdoses, and 37% of those deaths included a combination of opioids and stimulant drugs. The NIH also points out that these drugs are increasingly being tainted with fentanyl. 

"Genetics play a key role in determining health throughout our lives, but they are not destiny."

Nora Volkow, MD

The knowledge of the genetic basis for addiction has been limited, and most clinical trials have focused on specific substances rather than addiction overall. 

“Genetics play a key role in determining health throughout our lives, but they are not destiny. Our hope with genomic studies is to further illuminate factors that may protect or predispose a person to substance use disorders—knowledge that can be used to expand preventative services and empower individuals to make informed decisions about drug use,” said NIDA Director Nora Volkow, MD. “A better understanding of genetics also brings us one step closer to developing personalized interventions that are tailored to an individual’s unique biology, environment, and lived experience in order to provide the most benefits.”

What this means for you

NIH researchers have identified genes that are inherited across many addiction disorders, regardless of the substance being used. While biomarkers and individualized treatment still need to be developed, these findings can add to clinician understanding of the burdens of addiction that their patients face. 

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