Alcohol can whack the brain

This is the picture a new study paints of how different levels of alcohol affect a driver's brain: The first drink makes it harder to stay in your lane; the second makes it easier to ignore the fact that you're headed for the ditch. The study is in the current issue of the journal Neuropsychopharmacology.

Nine test subjects made a series of simulated drives in a brain-scanning device after consuming drinks intended to raise their blood alcohol level to 0.04 or 0.08, which in recent years has become the legal limit in many places.

For some runs they were given a placebo, a drink containing only a trace of alcohol served in a glass that reeked of it.

The researchers, Vince Calhoun and Godfrey Pearlson of Yale, found that the first drink appeared to produce a slight impairment of gross motor activities; but the subjects actually drove a little better, and a little slower, apparently aware of their possible impairment, than they did when they were completely sober, Pearlson said.

The second drink was followed by a significant decline in gross motor functioning.

Perhaps its most striking effect was on a region of the brain known as the orbitofrontal cortex; which plays an important role in what Pearlson described as error monitoring and inhibition, reviewing what other brain regions are proposing and squelching bad ideas.

"People were less aware of the consequences of their actions" after the second drink, Pearlson said. "They were poor judges of their deteriorating skills." As a result, they drove faster, left their lanes more often and were involved in more simulated collisions, leading Pearlson to conclude that the decision by some states to lower the blood-alcohol limit had been a good one.

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