Thursday, November 29, 2012

Are ADHD drugs Smart Pills?

It is scary to contemplate, but I am in the middle of my 22nd year teaching at a university.  Students use lots of techniques to try to get an advantage in their studies.  Obviously, some students resort to real cheating by trying to steal exams or to copy successful papers from past semesters.  Others try more subtle means.  There are students who come to office hours after each exam trying to get back points they lost by arguing about why their answer is really correct.  Starting about 10 years ago, there was an uptick in rumors about students who were buying medications normally used to treat ADHD to use to help them study.

Two of the most prominently used prescribed medications for ADHD are the stimulants methylphenidate (Ritalin and Concerta) and amphetamine (Aderall).  Do these drugs make you smarter?

This question was addressed in a fascinating set of papers in the September, 2011 issue of Psychological Bulletin.  The issue begins with a broad review by Elizabeth Smith and Martha Farah and continues with a commentary by James Swanson, Timothy Wigal, and Nora Volkow and a second commentary by Glen Elliott and Mark Elliott.

Before starting this discussion, it is important to make a point made by all of the articles (and particularly the commentaries by Swanson Wigal and Volkow and by Elliott and Elliott).  These ADHD medications are Schedule II drugs.  It is illegal to take them without a prescription.  An important part of the reason why it is illegal to take them is that they are potentially addictive.  The haphazard way that people who try these drugs to improve their cognitive performance may actually increase the likelihood of addiction compared to the regular schedule of use by ADHD patients. 

Do ADHD stimulants make you smarter?  Smith and Farah looked at 45 published papers examining different kinds of cognitive tasks. 

You might think that these medications would help people with executive control.  Most people think of ADHD as a difficulty with controlling thought, and so perhaps ADHD medications help with control.  In fact, over half of the studies they found that examined aspects of control showed no effect of the medications at all compared to a placebo.  For example, people often have difficulty giving up a small reward now in order to get a larger reward in the future.  ADHD medications do not make people more likely to forgo the smaller reward in order to take the larger reward.  

So, where do ADHD medications have an effect?  The evidence that Smith and Farah review suggests that when people are given rote learning tasks, their performance is improved by ADHD stimulants.  A rote learning task is one in which people have to memorize the items on a list.  These effects are strongest when people learn the items on the list and have to remember them at least a day after learning.  This effect does seem to come from learning, because the participants do not need to be on a medication during the test in order to see the effect.

It is important to be clear that few studies have looked at memory for complex kinds of information that require real deep understanding of the material.  So, it is impossible to know whether ADHD stimulants are just helping with learning the sorts of random items that typically appear on memory tests or whether they would also help with the kinds of complex knowledge that must often be learned in high school and college classes. 

The other place where ADHD stimulants seem to have some effect is with what is called working memory.  Working memory is the amount of information that people can hold in mind at the same time.  About half of the studies Smith and Farah reviewed suggest that these medications have no effect on working memory, while the other half show small effects in which the medications improve performance.  This improvement is often seen most strongly in those people whose normal working memory capacity is the smallest. 

What does all this mean?

Any pill is a blunt instrument.  It has pervasive effects across the brain and body.  Being smart, though, is a more subtle interaction among regions of the brain.  So, it is hard to truly make yourself smarter with a pill.

In addition, understanding the effects that an ADHD stimulant may have depends on other characteristics of the person.  For example, Smith and Farah point to new studies being done that look at a specific gene that is responsible for breaking down the chemicals dopamine and norepinephrine in the brain.  These chemicals are neurotransmitters that affect the way neurons in the brain operate.  The effects of ADHD stimulants appear to be different depending on which version of this gene a person has. 

Remember, ADHD stimulants are strong medicines that have the potential to lead to addiction.  So, there are serious costs that come with the modest benefits that the pills might provide.

Finally, it is not clear that the benefits of ADHD medications truly are benefits.  The strongest effect of ADHD medications is that they seem to enhance learning of items from a list.  There are times, of course, where it is important to learn arbitrary kinds of information.  I remember taking a neuroscience exam in college for which I had to know the names and locations of many brain regions.  But, there are also lots of times where it is more important to know why something occurs rather than what happened.  It simply is not clear from the studies that have been done so far whether ADHD stimulants help with that kind of learning.  In some learning situations, it might be better to forget some of the specific details in order to remember the gist of what you have encountered.

In the end, it is important to be armed with facts when considering any kind of medication.  If you are seriously thinking about taking any kind of medication hoping that it will act as a smart pill, read the research yourself and make an informed decision.