I hate to beat the drum of obviousness, but everything we think, feel or do has a neurobiological correlate.
If you run for 20 miles, most of us are going to be out of breath and heave air in and out of our lungs as they try and supply enough oxygen to our body. If you just found out you have to give a presentation to an audience of 4,000 people and giving presentations isn’t your livelihood, chances are you’re going to feel your palms go clammy and you may begin to sweat. If you feel intense anger or rage at another person, I bet I’ll be able to measure your blood pressure hit the roof. Even just listening to music impacts our brain’s functioning (see Koelsch, 2005 for a nice summary of this).
So why is it news that when we hook someone who has a mental disorder like depression, schizophrenia or ADHD to electrodes, or take a brain scan with fMRI or PET imaging, we’re surprised to find people’s brains with these disorders look and function differently than people’s brains without these conditions?
Yet that’s exactly what’s hailed as ground-breaking science here in this Washington Post article published earlier this week about a study looking at the brains of 53 people with attention deficit disorder (ADHD) compared to a group of healthy control subjects using PET brain imaging technology. The article discusses this JAMA study that found that people with ADHD have brains that look different than those without (Volkow et al., 2009). Specifically the researchers found that “ADHD patients had lower levels of dopamine receptors and transporters in the accumbens and midbrain — two key regions of the brain directly involved in processing motivation and reward.”
Okay. So what?
This study tells us nothing about how these dopamine receptors got the way they did. Instead, it joins the growing number of studies that analyze the brain and tell us things like, the structure of the brain may influence ADHD, or that hundreds of gene variations are linked to ADHD, or that, it’s not that people with ADHD’s brains don’t have enough dopamine, it’s that the brain pushes dopamine in the wrong direction influencing a ‘speed’ response between nerve cells. I could go on, but I hope you get the point.
Hundreds of studies have now been done analyzing the brains and genes of people with mental illness, but it doesn’t feel like we are any closer to the truth than we were 10 years ago.
One of the reasons is because none of these kinds of studies shed any light on the real problem — how did people’s brains come to have these anomalies in the first place? News articles (and sometimes even researchers themselves) subtly suggest that it’s the brain abnormality that is causing the mental disorder (in this case, ADHD). But it could just as well be the other way around — the ADHD may be causing the brain changes.
That’s why I find it interesting when researchers, like those who did the most recent JAMA study here, go out of their way to find people who haven’t taken medications for their disorder. The researchers don’t want their results contaminated by the neurochemistry of the medications.
But neurochemistry isn’t affected only by medications. It’s affected by everything we do. If you can change your very brain structure simply by driving a cab, imagine what efforts like psychotherapy can bring about. Even simple exercise can impact our brain.
Then imagine what a disorder like ADHD could do to your brain (rather than the other way around)… If ADHD is caused by some third factor, something non-neurological (say, only for the sake of argument, parenting skills), wouldn’t we still expect to see changes in the brain? Yes, we would. And we wouldn’t have any idea about this third factor if we weren’t looking for it. So while you might be technically correct in prescribing a medication to combat the brain changes, one could completely miss the underlying cause of the problem in the first place. (To emphasize, this is completely a hypothetical argument to prove a point.)
While I believe studies such as this most recent one add to our overall knowledge and understanding of conditions like ADHD (especially when it comes to pharmaceutical remedies for them), I don’t think it does much to help answer what causes ADHD. Nor does it put us any more firmly in the camp of understanding these as some sort of pure “biological brain illness.”
Having said that, I do believe that ADHD and other mental disorders have neurological correlates. And perhaps those correlates are more substantial and have a greater impact than other kinds of things in our lives. What I object to is positioning these kinds of brains scan studies as some sort of breakthrough in our understanding of these concerns when they aren’t.
Read the full article: Brain Scans Link ADHD to Biological Flaw Tied to Motivation
Koelsch, S. (2005). Investigating Emotion with Music: Neuroscientific Approaches. In: The neurosciences and music II: From perception to performance. Avanzini, Giuliano (Ed.); Lopez, Luisa (Ed.); Koelsch, Stefan (Ed.); Manjno, Maria (Ed.); New York, NY, US: New York Academy of Sciences, 412-418.
Nora D. Volkow; Gene-Jack Wang; Scott H. Kollins; Tim L. Wigal; Jeffrey H. Newcorn; Frank Telang; Joanna S. Fowler; Wei Zhu; Jean Logan; Yeming Ma; Kith Pradhan; Christopher Wong; James M. Swanson. (2009). Evaluating Dopamine Reward Pathway in ADHD: Clinical Implications. JAMA, 302(10), 1084-1091.