It’s no accident that crowds of smokers often congregate outside their favorite bar. About 80 percent of heavy drinkers enjoy a regular nicotine fix, and this co-abuse is the leading cause of preventable death worldwide, according to the World Health Organization.
Despite this data, the genetic and chemical link between drinking and smoking has remained a mystery. That is, until now.
According to researchers from Australia, the connection between nicotine and alcohol addiction may lie in a pleasure center in the brain, called the nucleus accumbens, which also plays an important role in addiction.
“This study is very interesting,” says Andreas Heinz, director of the Department of Psychiatry and Psychotherapy at the medical school of the Free University of Berlin. It describes for the first time that the effects of alcohol and nicotine overlap in this important brain region.
In the new study, lead investigator Traute Flatscher-Bader, a postdoctoral research fellow at the University of Queensland in Australia, and her colleagues analyzed the expression of thousands of genes in the post-mortem brain tissue of smokers, alcoholics and those who enjoyed both drugs.
They discovered that a specific group of genes expressed in the nucleus accumbens were most active in people who abused both alcohol and nicotine. When overactive, we can speculate, these genes alter the structure of cells in the nucleus accumbens and may rewire this brain region, Flatscher-Bader says.
This finding may help us understand why both drugs are often consumed together — each drug appears to enhance the addictive properties of the other, says Heinz, who did not contribute to the work.
Flatscher-Bader notes that further studies will need to confirm whether these genes modify cells in the nucleus accumbens, and to what extent. Perhaps future tests will also reveal other important pathways or genes that can help untangle the pathology of alcohol and nicotine addiction.
Understanding the genetic and chemical link between these two addictions “may ultimately lead to improved treatment regimes, specifically tailored to alcoholics that smoke and those that don’t,” Flatscher-Bader says.
The study will be published in the July issue of Alcoholism: Clinical and Experimental Research.
