Does a Common Genetic Difference Underlie Alcohol and Nicotine Addiction?

For the first time, CAMH’s Dr. A.D. Lê and colleagues found experimental evidence to support the theory that a shared genetic determinant accounts for co-abuse of the most frequently used drugs in the world, nicotine and alcohol.

Studies show that individuals who suffer from alcoholism are more likely to smoke, compared to the general population. In fact, the prevalence of smoking in people with alcoholism is about 3 times higher than in the general population. Results from studies involving twins have led to the theory that a common genetic difference puts twins at risk for both alcohol and nicotine addiction. However, investigating this theory in human studies is hindered by the possibility that smoking leads to drinking and vice versa. This study showed that an affinity for nicotine could be demonstrated before exposure to alcohol.

In a paper recently released in the Journal of Neuroscience, Dr. Lê and colleagues directly tested the hypothesis that a common genetic difference underlies alcohol and nicotine addiction. In the study, two genetically distinct kinds of rats learned to press a leaver and give themselves nicotine injections. Dr. Lê and colleagues study the rats’ behaviour, to determine if P rats (a heavy-drinking rat strain bred to prefer alcohol) were more likely to self-administer nicotine, versus NP rats (a strain bred for low alcohol preference). The scientists found that the P rats self-administered more than twice the amount of intravenous nicotine as the NP rats. In addition, the experiments showed that P rats were more vulnerable to nicotine relapse.

Dr. Lê and his co-investigators also found that these differences were specific to alcohol and nicotine. When both strains of rats learned to press a leaver to receive cocaine, each group took the same amount of the drug.

The results of this study provide a better understanding about the co-abuse of nicotine and alcohol. This kind of information could lead to diagnostic tools and targeted treatment programs to help prevent and treat alcohol and nicotine addiction.  

For more information on this work, visit http://www.jneurosci.org

 

 

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