By Melissa Healy
8:33 PM EDT, July 18, 2013
Just in time for the summer cocktail season, there's a research finding that offers a new recipe for excessive alcohol consumption. Let's call this cocktail a Tension Burner and ask the barman to go easy on the dopamine. First ingredient: stress hormones; next, add nicotine; third, add alcohol. Fourth, add more alcohol.
According to a study published Thursday in the journal Neuron, nicotine -- the main addictive ingredient in tobacco -- appears to prime the desire to drink alcohol, and to drink more alcohol. But, the study reveals, it takes stress hormones to seal the deal.
The study may help explain why alcoholism is roughly 10 times more prevalent in smokers than in non-smokers, and possibly why taking up smoking at an early age is a significant risk factor for subsequent alcohol abuse. But its finding that stress hormones play a key role linking tobacco addiction and alcohol abuse underscore that the relationship is not a simple one.
Typically, the introduction of alcohol boosts the presence of the neurotransmitter dopamine in the brain's ventral tegmental area and nucleus accumbens, parts of the limbic system involved in processing such basic drives as pleasure, reward and addiction. This dopaminergic flood would bring on improved mood, dampening the effects of stress and bringing on that familiar mellow buzz.
Nicotine, however, upsets this response, found a team of Baylor College of Medicine researchers led by neuroscientist John A. Dani. When this part of the brain is already bathed in stress hormones and you add nicotine, alcohol suppresses the flood of dopamine throughout the basal forebrain. The natural response might well be to take on more alcohol in a bid to attain that elusive feel-good buzz.
And that is exactly what lab rats at Baylor did.
Among young rats allowed to take sips of alcohol at will, those that had been given an earlier dose of nicotine would help themselves to more and larger doses of alcohol, researchers found. The effect lasted long after the 45 minutes it would take for nicotine to be metabolized by the rats: A nicotine treatment 15 hours before the rodents were allowed to imbibe prompted them to drink significantly more, the researchers found.
But stress hormones proved to play a crucial role in catalyzing this effect.
When researchers administered a drug that dampened the effect of corticosteroids before plying the rats with nicotine, they found that nicotine-treated rats helped themselves to no more alcohol than those who did not get nicotine.
The findings may help identify strategies that make abstention from alcohol easier. But in suggesting that there is a "neurophysiological basis for the observation that nicotine use can increase the reinforcing properties of alcohol," it may also underscore that tobacco's harms may extend well beyond cancer and heart disease, and that the toll it has taken may go well beyond the 100 million people it is estimated to have killed in the 20th century alone.
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