WASHINGTON

NEW Year’s Eve tends to be the day of the year with the most binge drinking (based on drunken driving fatalities), followed closely by Super Bowl Sunday. Likewise, colleges have come to expect that the most alcohol-filled day of their students’ lives is their 21st birthday. So, some words of caution for those who continue to binge and even for those who have stopped: just as the news is not so great for former cigarette smokers, there is equally bad news for recovering binge-drinkers who have achieved a sobriety that has lasted years. The more we have binged  and the younger we have started to binge  the more we experience significant, though often subtle, effects on the brain and cognition.

Much of the evidence for the impact of frequent binge-drinking comes from some simple but elegant studies done on lab rats by Fulton T. Crews and his former student Jennifer Obernier. Dr. Crews, the director of the University of North Carolina Bowles Center for Alcohol Studies, and Dr. Obernier have shown that after a longstanding abstinence following heavy binge-drinking, adult rats can learn effectively  but they cannot relearn.

When put into a tub of water and forced to continue swimming until they find a platform on which to stand, the sober former binge-drinking rats and the normal control rats (who had never been exposed to alcohol) learned how to find the platform equally well. But when the experimenters abruptly moved the platform, the two groups of rats had remarkably different performances. The rats without previous exposure to alcohol, after some brief circling, were able to find the new location. The former binge-drinking rats, however, were unable to find the new platform; they became confused and kept circling the site of the old platform.

This circling occurs, Dr. Crews says, because the former binge-drinking rats continued to show neurotoxicity in the hippocampus long after (in rat years) becoming sober. On a microscopic level, Dr. Crews has shown that heavy binge-drinking in rats diminishes the genesis of nerve cells, shrinks the development of the branchlike connections between brain cells and contributes to neuronal cell death. The binges activate an inflammatory response in rat brains rather than a pure regrowth of normal neuronal cells. Even after longstanding sobriety this inflammatory response translates into a tendency to stay the course, a diminished capacity for relearning and maladaptive decision-making.