Your Brain on Alcohol

I just got back from a few weddings on the East Coast. I had a lot of fun, and of course it got me thinking I should write a post about one of the most important aspects of a successful wedding: alcohol. (Well yes, love is important too, but I needed to find an intro to talk about the effects of alcohol on the brain).

Alcohol has a big effect on three brain regions in particular. The first is the cerebellum, which is that blob of a thing that hangs off the back of the rest of your brain. The second is the nucleus accumbens, which is a small structure nestled deep in the middle of the brain. The third is … I’ll give you one guess and it rhymes with “tree bundle vortex”.

Let’s start with the prefrontal cortex. Alcohol has an inhibitory effect on the prefrontal cortex, because it enhances the activity of a neurotransmitter called GABA. GABA’s job is to lower neuronal activity, so enhancing GABA reduces neuronal activity even more. Doing this in the prefrontal cortex leads to reduced social anxiety and ultimately lowering your inhibitions. As I discussed in a recent post the dorsomedial prefrontal cortex helps you figure out what other people are thinking, which includes feelings of social judgment. Reducing your feeling of other people judging you, reduces your social anxiety. An adjacent region, called the dorsolateral prefrontal cortex, is responsible for controlling your impulses. When it gets inhibited by alcohol it no longer stops you from succumbing to your impulses. So what happens when you combine caring less about what people think of you with lowering your impulse control? Well I think that helps explain all those bad decisions you made while drunk at your brother’s wedding (or maybe that was me).

In the nucleus accumbens alcohol causes release of a neurotransmitter called dopamine (Boileau et al 2003). In fact this is one of the primary reasons that alcohol is pleasurable. All of the naturally pleasurable things in life release dopamine in the nucleus accumbens: sex, eating, going to the bathroom, etc… So let’s all raise a glass and give a toast to dopamine!

Lastly, the cerebellum is responsible for coordination of muscles, everything from your feet to your mouth. It’s even responsible for balance and certain eye movements. When alcohol enhances the effects of GABA in the cerebellum it disrupts all these functions. In fact, the cerebellum is particularly sensitive to alcohol, which is why if a cop suspects you of drunk driving they do several tests to assess cerebellum function (including watching your eye movements, and making you balance). The effect of alcohol on cerebellum function also explains why after a few too many Long Island iced teas you’re likely to have slurred speech, troubling walking, get dizzy and fall into the lake at your brother’s wedding.

In conclusion: please drink responsibly!

If you liked this article then check out my book - The Upward Spiral: Using Neuroscience to Reverse the Course of Depression, One Small Change at a Time

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