Scientists find that nicotine use increases compulsive alcohol consumption

http://www.eurekalert.org/pub_releases/2015-04/sri-tsf041415.php

Public Release: 14-Apr-2015
Scripps Research Institute

Why do smokers have a five to ten times greater risk of developing alcohol dependence than nonsmokers? Do smokers have a greater tendency toward addiction in general or does nicotine somehow reinforce alcohol consumption?

Now, a study led by scientists at The Scripps Research Institute (TSRI) helps provide insight into these questions, showing that, in rat models, nicotine exposure actually promotes alcohol dependence.

"It's a vicious cycle," said TSRI biologist Oliver George, a senior author of the new study. "Nicotine makes individuals crave alcohol to 'reward' the brain and reduce stress."

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Previous studies from George's lab had shown that nicotine activates certain "reward" neurons in the brain--giving positive reinforcement to keep smoking. At the same time, nicotine activates "stress" neurons in the brain, giving negative reinforcement. This stress can lead individuals to crave alcohol to both activate the reward system and calm the stress system.

The compulsive alcohol consumption and neurological pathways seen in the new study suggest that alcohol works with nicotine to further activate the brain's reward system and dampen the stress of nicotine exposure.

This interaction may explain why it is difficult for smokers to quit drinking, and vice versa. Interestingly, the combination of neurons activated by nicotine and alcohol together is different from the neurons activated by each substance on its own.