Genetic Study of Nicotine and Alcohol Use Offers Insight into Addiction

A new genetic study looking at smoking and drinking has confirmed much of what we already know about their impact on your health, but the study also found genetic associations that offer new insights into alcohol and tobacco use, as well as addiction.

Published this week in the journal Nature Genetics, the study is one of the largest genome-wide association studies to date, using data from more than 1.2 million people. Researchers working on this study found more than 500 genetic variants associated with smoking and alcohol use, including newly identified genetic associations that link alcohol and tobacco use with the release of dopamine in the brain. Dopamine plays an essential role in reward-based behavior, and the finding may help researchers better understand why quitting smoking or problem drinking is more difficult for some than it is for others.

Smoking, Drinking and Disease

The study also showed that tobacco use was closely associated with a range of diseases — not just lung cancer. While that was not unexpected, the researchers were surprised that social drinkers — those who drank a moderate amount of alcohol each week — had fewer illnesses. This adds more fodder to the debate around whether moderate drinking may be beneficial to one’s health. Of course, there may be other explanations for this; for example, individuals who are more open and extraverted may be more likely to be social drinkers, and individuals with outgoing personalities may have better outcomes than those who are more anxious and less social, who in turn may be less likely to drink.

Much of the data for this study came from 23andMe customers who consented to participate in research and answered survey questions about smoking and drinking. The remaining data came from more than two-dozen other study cohorts. Led by researchers at the University of Minnesota, the work on this study also involved contributions from dozens of other scientists from institutions that are part of GWAS & Sequencing Consortium of Alcohol and Nicotine Us (GSCAN).

Other Studies

This is one of several genetic studies published in the last few months to look at addictive behavior, including alcohol and nicotine use. In November, a team of researchers found shared genetic influences between alcohol dependence and depression, ADHD, and schizophrenia. They also looked at genetic correlations between alcohol dependence and individual traits, like nicotine addiction, depression, and BMI. That study also found a distinct difference between casual alcohol consumption and heavier alcohol use, suggesting that social drinking is not associated with depression, but problem drinking and alcoholism are.

Another study on alcohol dependence published last fall also found genetic associations that overlapped with increased genetic risk for major depression, schizophrenia, and attention-deficit/hyperactivity disorder.

The GSCAN study published this week adds to these previous findings, offering more information to better understand the genetics of substance use and addiction.

You can find the paper in Nature Genetics.