Here’s something to keep in mind as the holidays unfold: if you drink alcohol when you’re stressed, you may be flipping a brain switch that makes heavier drinking all the more likely. That’s the finding of a new animal study on the neural effects of drinking, and stressed humans should take note of the results.


David-DisalvoDavid DiSalvo is a science, technology, and culture writer whose work appears in Scientific American Mind, Psychology Today, Forbes, the Wall Street Journal, Mental Floss, and other publications. He is also the writer behind the well-regarded science blogs Neuro narrative and Neuro psyched. He is frequently interviewed about science and technology topics, including appearances on NBC Nightly News and CNN Headline News.

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A group of rats were put under heavy stress for an hour, and 15 hours later their blood was tested to find out how much of a sugar-water and ethanol solution they’d been drinking (rodent version of a stiff cocktail served at an open bar). The researchers found that the stressed rats drank significantly more of the solution than an unstressed control group. And here’s the really interesting part: the booze slurping went on for weeks after the original exposure to stress.

Yes, these are rats and, no, humans aren’t rats, but the brain chemistry involved is surprisingly similar, offering convincing reason to think a similar thing is happening in human brains when we imbibe while stressed. The scientists think high levels of stress reduce the brain’s normal response to alcohol, specifically the dopamine response in the vector of brain areas known as the reward center. When you throw back a drink in a low-stress situation, your brain receives the booze with a predictable reward center response. But when you drink in a high-stress situation, that response is subtly blunted–it doesn’t quite deliver the same chemical goods–which prompts more drinking.

drinking

At least that’s what happened with the rats. In fact, the process was profound enough to produce identifiable changes in their brains. The researchers reported that the reward circuitry in the rodents’ brains was visibly altered after the rats started drinking—neurons that would normally put the brakes on the reward response were switched to “go” mode, compelling the rats to keep drinking with no sign of stopping.

To figure out if the effects were reversible, the researchers gave the rats a chemical to restore the altered neural circuitry to its pre-stress condition, and it worked. The rats started drinking less of the booze and water solution as their brains returned to normal.

This research pairs up well with a wealth of recent studies showing that our brain’s reward center is prone to subtle hijacking. The slow roll of addiction likely begins just this way for many people, with stress playing a key part in triggering the process.

"The stress response evolved to protect us, but addictive drugs use those mechanisms and trick our brains to keep us coming back for more," said study co-author John Dani, PhD, chair of the department of Neuroscience in the Perelman School of Medicine at the University of Pennsylvania.

 

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