Last spring, I took a one-credit seminar in which each week, a different faculty member working on a neuroscience-related topic would come in and give a presentation on their research. One of the ones that stuck in my mind most was that of Louis Populin, who talked about the effects of Ritalin. Specifically, he talked about experiments on primates where researchers could freely alter the dosage and measure the effects on the primates’ behavior in cognitive tasks.

The experiments suggested that both cognitive performance–that is, are they doing the task right?–and ability to concentrate first increased with dosage and then decreased. However, the effect on cognitive performance peaked first. This means that by the time the drug is producing peak effects on concentration, it has already started to have a negative impact on cognitive function. (Aside: SciAm recently did a 60 Second Science clip reporting broadly similar findings.) This is a big problem in practical terms, because the currently most widely-used techniques for treating ADHD are very crude. Teachers are responsible for identifying potential candidates, and for determining what dosage is most effective. However, teacher assessments are mainly based on ability to sit still, not cognitive function. For this reason, putting a child on Ritalin may not actually increase academic performance much. I think people have started to pick up on this, without the help of researchers: popular worries about Ritalin seem to center on the image of a teacher who uses it more to treat their own headaches than help students. An ideal test for dosage on ADHD children would involve a brief computer task, administerable in the doctor’s office, that would test both cognition and concentration. That would allow doctors to fine-tune the dosage, and find one that results in a good balance between the two benefits of Ritalin.

After each seminar, we students got an opportunity to ask a question of the presenter via e-mail. What I asked was this: “what are the drawbacks to using Ritalin on normal subjects?” Unfortunately, while we sometimes got big files sent back to us with answers to everyone’s questions, this was only sometimes. And that week turned out to be one of the not-times.

The question is a rather important one, because it wasn’t as if the primates used in Populin’s reasearch had been diagnosed with attention deficit disorder. The improvement in cognitive functioning they saw wasn’t, then, making up for a disorder. It was an enhancement over the baseline. Heck, ADHD is defined as a deficit in attention, not a deficit in cognitive functioning, so if you take Populin’s advice on dosage for kids diagnosed with ADHD, you may actually end up giving them an edge over non-ADHD kids.

The debate about cognitive enhancement isn’t new to the web–see this post by Ed Young at ScienceBlogs for a good round up. The seminar presentation, though, strikes me as a particularly elegant example of how hard these issues are going to be to avoid.