Abusing Substance Abuse Data
I haven't covered the issue of alcohol for a while, but a recent set of headlines had a reek of moonshine about them. "Heavy social drinkers show brain damage" ran the Reuters headline in many news outlets. The <?xml:namespace prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />UK press, as usual, was more creative. "Three glasses of wine a day 'a health risk'" said the sober Scotsman, while the Glasgow Herald was more direct: "Boozers face brain damage." Yet the study actually told us little we didn't know already. Social drinkers can continue their imbibing without worry.<?xml:namespace prefix = u1 /> <?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" />
The cause was a study by researchers from the San Francisco branches of the University of California and the Department of Veterans Affairs Medical Center. From MRI scans of 46 heavy drinkers and 52 light drinkers, they concluded that, "Community-dwelling heavy drinkers who are not in alcoholism treatment have brain metabolite changes that are associated with lower brain function and are likely of behavioral significance."
Given the press coverage, one might assume that the "social drinkers" enjoyed two or three drinks two or three times a week. That was not the case. "Social drinkers" was a misinterpretation of the definition of the report's subjects as "socially functioning," in other words active in the community rather than seeking treatment for alcoholism. The minimum qualification to count as a heavy drinker for the study was 100 drinks per month over the past three years. This is not the generally accepted definition of a "social drinker" as someone who enjoys the odd drink in a social situation with friends but who rarely drinks otherwise.
In fact, the study went even further from the generally accepted use of the phrase. Of the 46 heavy drinkers, 41 met standard criteria to be classified as alcohol dependent, and the other 5 qualified as abusers of alcohol. In other words, the study looked at alcoholics, not "social drinkers."
One might therefore conclude that the study simply showed that alcoholics in denial are as likely to get brain damage as alcoholics in treatment. That is true, to an extent, but there were some interesting side notes. For instance, it appears that a family history of alcoholism protects somewhat against the brain damage, possibly thereby proving some truth in the old joke, "Drinking kills brain cells, but only the weak ones." Moreover, there were anomalous findings in that binge drinkers seemed to display less of one type of damage than steady drinkers, which the researchers found surprising.
Moreover, the "brain damage" the researchers found also does not fit the popular interpretation of that term, which implies noticeable impairment. As lead researcher Dr. Dieter Meyerhoff said, "Heavy drinking damages your brain ever so slightly, reducing your cognitive functioning in ways that may not be readily noticeable" (emphases added).
It was the journalists rather than the scientists who added the spin here. The researchers found that alcoholics not receiving treatment for their problem suffer from a variety of barely noticeable cognitive impairments. The story got written up as heavy (whatever that means) social drinkers getting brain damage. That may be literally true, but it is likely to conjure up a far different picture than the researchers intended.
Yet it is not just in alcohol research that non-stories get exaggerated. A recent report by the Center on Addiction and Substance Abuse (CASA) at Columbia University suggests that many more teens are in treatment for marijuana abuse than alcohol abuse, which might put the hysteria about teenage alcoholism in perspective if it is true. Yet confidence in the findings is not enhanced by this supposedly worrying suggestion:
Among youths aged 12 to 17 who have ever tried marijuana, the mean age of initiation is 13 and a half. The mean age of initiation among adults aged 18 to 25 who have ever tried marijuana is 16.
It should come as no surprise that the mean age of first use for a younger group is less than that for an older group. What about all those in the 12-17 group who haven't tried marijuana yet but will do when aged 18 or older? This is a meaningless finding, yet it is advanced seemingly in support of CASA President James A Califano's assertions about the dangers of the drug.
We know that alcohol—and marijuana for that matter—are dangerous when abused. Yet we also know that alcohol seems to confer a degree of health benefit when used in moderation. Suggesting that moderate use of alcohol—as implied by the use of the term "social drinker"—might damage the brain is therefore the height of journalistic irresponsibility. It's enough to drive one to drink.