I think this research is pointing out that using ADHD-like medication as "smart drugs" for school work in people without ADD/ADHD is problematic. I don't know exactly how they are used by those without a medical need, but I thought it was as temporary fixes, not taken habitually.

The article specifically says:

> More work will be needed to establish exactly why these drugs have these effects in those without a medical need for them, as well as to explore the potential impacts of other so-called smart drugs.