At a recent briefing by John Walters — the nation’s drug czar — drug use patterns by youthful offenders were outlined.

After falling steeply between 1979 and 1991, the favorable trend reversed as drug abuse climbed steeply between 1992 and 1997, when it reached a plateau. Starting in 2001 a favorable trend downward was reestablished, resulting in an aggregate 19% decline by 2006.

While it is easy to overemphasize short-term statistical information, it is also true that young people who are initiated to drug use in their teen years are at a far greater risk for dependency than those who begin drug use during maturation. Even more compelling, young people who do not use drugs between ages 18 and 20 are highly unlikely to ever develop drug dependency. Hence driving down drug use during this youthful period is critical in the overall assessment of this national trend.

That said, albeit unmentioned by Mr. Walters, the pattern of drug use is seemingly correlated to the party leader occupying the White House.

For example, youthful drug use rose between 1977 and 1981 while Jimmy Carter was president, declined between 1981 and 1991 when Ronald Reagan and George H.W. Bush were presidents, rose between 1992 and 2001 when Bill Clinton was president, and has been in a steady decline between 2001 and the present under George W. Bush.

Is there a relationship between the party in power and the rise and fall of drug use?

Are the statistics mere anomalies? Is there a view about drugs implicitly or explicitly communicated by Democrats and Republicans that results in the rise and fall of drug abuse?

Obviously causal relationships and correlations enter the realm of speculation. Nonetheless, the evidence is suggestive. Could it be that Presidents Carter and Clinton, the two Democratic presidents in this 30-year history, were inclined to deemphasize resistance to youthful drug use, or did they communicate implicit messages that condoned such use?

Mr. Clinton did admit to marijuana use, even though he didn’t inhale. George W. Bush readily admits to alcohol abuse, albeit he is an avid teetotaler who warns against the dangers of alcoholism. My suspicion is this may be extreme speculation leading to unwarranted conclusions.

What might be a more fruitful line of inquiry is the cultural tone set by the respective parties. If Hollywood is any guide — clearly a dubious one — Republican leaders are invariably portrayed as uptight, narrow-minded, and frigid.

In one segment of “Desperate Housewives” a leading character finds herself in bed about to engage in sexual activity, when she looks up at her lover and says, “I can’t do it; I’m a Republican.” This is presumably a laugh line.

Yet curiously there may be an element of truth to this situation. Is it possible that Republicans, who tend to be more traditional and religious than their Democratic counterparts, also are more concerned about normative moral principles?

Obviously this judgment may vary within parties as well. There is a difference between Senators Kennedy and Lieberman. Moreover, when the moral card is employed it applies to Reps. Mark Foley and Trent Franks.

Clearly nuance is critical. It should be noted too, as Tom Wolfe once argued that, “moralisms are the foxholes for incompetents.” Surely one should be careful in casting moral arguments.

However, when one considers the charges leveled against Mr. Bush, it seems reasonable that he should take credit for a reduction in youthful drug use, despite my already mentioned hesitation.

After all, he’s been charged with neglect after Hurricane Katrina, mistreatment of captured terrorists, and a host of other malefactions he probably had no way of controlling. Since presidents get blamed for everything that goes wrong, they should get some credit for things that go right as well.

Moreover, it may be that Republican presidents set a tone and forceful strictures that influence drug policy. The evidence is not dispositive, but it is suggestive. In the present Washington environment that isn’t bad.

Mr. London, president of the Hudson Institute and professor emeritus of New York University, is the author of “Decade of Denial.”