Tuesday, May 24, 2011

Latest "Binge Drinking" Study Less than Meets the Eye

Stop the presses!  New study links binge drinking to memory loss in college students!

Now before readers all respond with a resounding "DUH!", we should clarify that the study in question, which looked at 18-20 year old college students in Spain, found that those who admitted to "binge" drinking (six or more drinks in the same occasion at least once a month) performed slightly worse on a test of verbal memory (when sober) than those who did not.  Already the media has taken it and ran with it, with some people inferring that this is evidence of permanent brain damage.  Even worse, some folks have even interpreted this study as justification for the 21 drinking age.  And those lines of reasoning are flawed to say the least, especially when one considers what the study actually found rather than the speculation of the alarmists.

First of all, the actual study was a cross-sectional study, and although it did control for several potential confounders, its design made it impossible to determine whether the link was causal since one could not test for temporal precedence (a crucial criteron of causation), much less truly isolate the drinking from all other variables. Second of all, the size of the effects was small (e.g. the "bingers" remembered 2-4% less information from a story compared to controls), not always statisically significant, and was in all cases within a standard deviation.  For the word list recall, the difference in the number of words recalled was less than a single word.  These differences would be of little to no practical significance, even if they technically were statistically significant.  Third, no gender differences of the apparent effects were noted, despite the fact that women are generally more sensitive to alcohol than men as a rule, and that the definition of a "binge" was not gender-specific.  Fourthly, we know nothing from the study about how long such effects persist, since the participants were only required to abstain from alcohol or drug use for 24 hours, and such abstinence was not monitored.  Hangovers may very well last longer than 24 hours in some cases, which may confound results.  Finally, the study design precluded determination of a dose-response relationship, so the all-important question of "how much alcohol is too much" relating to neurotoxicity remains unanswered by this investigation.

This should remind us all of another relatively recent cross-sectional study of 18-20 year old first-year university students in Spain, that looked at the effects of so-called "binge" drinking on the brain. In this study, 95 students (42 "bingers", 53 controls) were given tests of attention and working memory, and their specific brain waves were monitored with electrodes. No statistically significant differences were observed between the two groups in terms of actual performance, but the electrophysiological test suggested that more attention was expended to complete a given task among the "binge" group, as well as other electrophysiological differences. This is a lot more nuanced and less certain than the media are implying, and hardly represents "dain bramage."   EEG differences were also noted in another recent study of a broader age group of young adults in the United States, but such differences were largely confined to "high-binge" drinkers (10 or more drinks per drinking session) rather than those who had 5-7 drinks per session.

Another recent study, done on 18-20 year old college students in Belgium, also found similar electrophysiological differences, but again no behavioral performance differences for some reason.  In this study, which was one of the very few longitudinal studies on the matter, there were no differences in alcohol consumption or electrophysiological results at baseline, but both changed significantly in the "binge" group when measured 9 months later, but not in the control group. However, we should keep in mind that the binge group averaged 12.5 units (about 9 American drinks) per binge session, and two such binge sessions per week, which is quite extreme. Number of drinks per week averaged a whopping 35 units (25 American drinks) in the binge group, while the control group drank barely even one drink per week. And some participants drank as recently as three days before the tests as well, potentially conflating short and long term effects, though this was ostensibly controlled for. One good thing about this study, however, was that the sample size was significantly larger than the aforementioned one, and due to its longitudinal nature there was both a before test and and after test, enabling us to control for preexisting differences between the two groups. 

The biggest flaw in all of these studies was the fact that there was no over-21 comparison group. So we simply cannot infer anything at all about age from this piece of research. Absolutely zilch. A better method would have been to have three groups each examined separately: 15-17, 18-20, and 21-24 years of age. But no study that we know of meets this standard.  This would help to settle the nagging question of whether or not it actually is worse to drink at 18 rather than 21. Or perhaps some people are afraid of the possibility that their rationale for keeping the drinking age at 21 would be debunked if such a comparison was done. As yet, there is essentially ZERO hard scientific evidence that drinking at 18 is significantly worse than doing so at 21, ceteris paribus, but a plethora of evidence showing that excessive drinking is unhealthy at any age.  Indeed, a 2002 study of alcoholics found no significant differences in the long-term effects on participants' neuropsychological performance with respect to age of onset (before vs. after age 20) of alcohol abuse. And still another study in 2007, this time of 21-25 year olds (you know, folks who are legally allowed to imbibe) who were self-identified heavy drinkers (more than 25 drinks per week), found that subtle brain changes are not exclusive to those under the magic age of 21.

Drinking ludicrous amounts of alcohol is dangerous, period.  Regardless of age. That, if anything, should be the moral of the story. Keeping the drinking age at 21 only encourages such extremes, especially for college students.

We at 21 Debunked provide this for informational purposes only and do not in any way advocate drinking of any kind, underage or otherwise.

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