Does Smoking Drive Us to Drink: Nicotine, Combined with Stress Hormones, Affects Brain Chemistry in a Way That May Increase Alcohol Use

Article excerpt

Smoking has been associated with a risk for alcohol abuse, but, until recently, nobody quite understood why. Research from Baylor College of Medicine, published in the journal Neuron, sought a connection between nicotine exposure and the brain's subsequent chemical response to alcohol. What the scientists found was that smoking makes your brain want to drink more.

Dopamine is a neurotransmitter--a chemical that transmits information from one neuron to another. Neurotransmitters serve a wide range of purposes. The neurotransmitter melanin helps to regulate our circadian rhythms; oxytocin promotes bonding between mothers and infants. Dopamine plays myriad roles, from influencing attention span to altering mood to aiding us in voluntary muscle control. It also factors into addiction.

When a person is exposed to certain mind-altering substances, such as alcohol or cocaine, dopamine levels increase. As the drug's effects wear off, dopamine levels return to normal. Over time, the brain becomes accustomed to frequent floods of dopamine as a result of drug or alcohol use, creating a chemical "need" for that particular substance.

In the experiment, rats were first injected with either nicotine or saline. Three hours later, they were intravenously administered alcohol until their brain alcohol concentrations reached roughly the same levels as a human's might. Nicotine's half-life--the time it takes for nicotine levels to fall to half their original concentration--is about 45 minutes in rats. Researchers chose to wait three hours after nicotine injection to minimize the nicotine's pharmacological effects.

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The rats that had been injected with saline (the control group) experienced an increase in dopamine compared with their original, pre-saline and pre-alcohol levels. Those that had been injected with nicotine did not show higher dopamine levels. …