Addiction Is Tied to More Than Social and Family Issues 

Have you ever wondered why some people can smoke cigarettes for a long time and then quit while others become addicted for life? 

And why can some people kick an alcohol-abuse problem forever while others resume drinking after they stop hitting the bottle? 

Researchers at the UNC School of Medicine say at least some of our addictive tendencies are found in our genes, which make some of us more prone to addiction. 

“We know from studies of twins that genetics may account for why some people abuse substances, aside from environmental factors such as family issues or personal trauma,” said Hyejung Won, Ph.D., assistant professor of genetics and member of the UNC Neuroscience Center. 

“But now we have not only identified genes linked to cigarette smoking and drinking, but we also understand a little more about the genetic framework of addiction, which could eventually lead to the creation of medications to address it.” 

More Genes Linked to Addictions 

Researchers found that genes linked to smoking and drinking addiction are overrepresented in certain kinds of neurons, area cells that trigger other cells to send chemical signals through the brain. 

The study also found the genes connected to cigarette addiction were linked to perception of pain, response to food and abuse of other drugs such as cocaine. 

The genes associated with alcohol were linked to stress and learning as well as the abuse of other drugs such as morphine. 

Long-term substance use disorders have been linked to many conditions, ranging from liver disease to mental illness. However, there aren’t many medical treatment options available because doctors don’t understand the biological processes involved. 

And that’s what researchers are trying to understand: how genetics could affect the biological processes of addiction. 

Linking Genetics and Biology 

Previous genetic research called genome-wide association studies (GWAS) provided a way to identify areas in the genome that play a role in nicotine addiction or drinking heavily. Researchers compared these areas in individuals experiencing nicotine and alcohol addiction with areas in the genome of those individuals who do not exhibit addictive traits. 

However, genome-wide studies don’t reveal much information on how those genes affect a trait. That’s because the genes are in what scientists call “non-coding” regions of the genome. 

In other words, the genes in those regions do not translate, or code, their genetic information into the creation of proteins that then perform a specific function. What happens biologically in those areas remains a mystery. 

The team at UNC applied new computational tools to study the genes. The tools had previously been used to identify the genes and the biology associated with several brain disorders. It had not been used to study addictions. 

“Our analyses showed that expression of genes shared between cigarette smoking and alcohol-use traits can be altered by other types of substances such as cocaine,” Dr. Won said. “By characterizing the biological function of these genes, we will be able to identify the biological mechanisms underlying addiction, which could be generalized to various forms of substance abuse disorder.” 

The study may also help doctors identify potential new treatments for substance use disorder. 

“We found that antipsychotics and other mood stabilizers could potentially provide therapeutic relief for individuals struggling with substance abuse,” said Nancy Sey, a graduate student in the Won lab and the first author of the paper. “And we’re confident our research provides a good foundation for research focused on creating better treatments to address drug dependency.” 

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