Wednesday, June 17, 2009

The New York Times had an article that casts doubt upon all the research which supposedly shows moderate drinking to be good for your health.  They finally seem to have noticed the fact that in all the years of breathless reporting on this topic, they've never presented an iota of data to support a causal relationship there.  There a correlation -- it's clear from a hundred studies that moderate drinkers are likely to be healthier than both heavy drinkers and teetotalers -- but not only is there no evidence of cause, there's not much in the way of plausible causal mechanism hypothesized that I've ever heard.

The problem is that the human mind abhors (an unexplained) correlation, and will quickly latch upon whatever plausible causal story presents itself.  Our cognitions lust after causalities and chains of this-then-that's.  (Journalists, of course, professionalize this -- spinning their stories  out of a nest of familiar themes and narratives that arrive to us as 95% soothing confirmation and 5% anxiety-inducing provocation -- but that's a thought for another post.)

When I hear any science report in the news, I'm contrarian enough to immediately run the proffered narrative through a couple of variations.  In this case, could it be that moderate drinking and health both come about from something else?  Of course.  It only takes a moment to imagine various scenarios.  Could it be that the previous reports have had it backwards and good health causes moderate drinking?  Or at least that poor health causes both alcohol abuse and abstinence?  The Times article hints that this might be the case -- that teetotalers may be unhealthy because unhealthy people give up alcohol -- and poor health can also lead to alcohol abuse.

In a great number of science articles and nearly all health articles, a few moments of questioning quickly discredits the original causal claim -- which is usually the main "claim" or message of the article.  What's left in the rubble is evidence for a correlation -- and a best-guess about cause.   Also worth noting is that the choice of explanatory narrative isn't driven by the evidence at hand, but by the writer's and audience's cognitive and cultural needs and desires.  That is, the choice about how to imagine the causality usually has more to do with confirming or less often (as in the case of the original alcohol reports) disconfirming people's pre-existing prejudices.  

But in any case, it's nice to see the Times finally stating the obvious.