The report wonders whether it’s due to conservative tendencies among doctors. But Viagra and Modafinil both became available in the U.S. in 1998. Conservatism doesn’t explain why doctors are slower to accept Modafinil than Viagra. Although maybe combined with more patients asking for Viagra it would be plausible.
Concern over side effects might explain why doctors are less comfortable with Ritalin, but not why three different cognitive enhancing drugs all produced similar comfort levels – about half that of Viagra. And I see no signs that Modafinil is much riskier than Viagra.
Could it be concern that Viagra has an equalizing effect (making people more normal), whereas cognitive enhancers make people who can afford them smarter than the less fortunate? Partly – doctors were more willing to prescribe cognitive enhancers for older patients than younger ones. But the cross-drug comparisons were done for a case where “the patient was a 40-year-old reporting symptoms consistent with the label indications for the respective drug”. I’m pretty sure the label indications describe a patient who is functioning well below normal.
The obvious conclusion part of what’s happening is that doctors believe sex produces larger benefits than cognitive enhancement. If we ignore potentially important externalities such as sexually transmitted diseases versus improved science/technology (would doctors admit to doing that?), I could make a decent case for sex being more valuable. There’s no shortage of evidence that sex makes people happy, whereas there seems to be little or no correlation between cognitive ability and happiness.