... she blinded me with science ... Aerobic Exercise and Attention Deficit Hyperactivity Disorder

One teacher, one scientist, and one paper; but how many conclusions?

Today's post is a little bit different, but this type of post will hopefully become a semi-regular thing as the 'she blinded me with science' series. I'm cross-posting with Dr. Kris. Dr. Kris and I met when she moved into my townhouse as a tenant while she was pursuing her Ph.D. in Genetics. She is a fabulous person, and I thoroughly loved living with her. Unfortunately, she was kidnapped by an errant boy-creature whom she subsequently married. I blame Stockholm Syndrome. Anyway, in an effort to class up the joint, I am doing a semi-regular science Wednesday with the good doctor. Prepare yourself for her being science-y and me being my typical irreverent self. If you like what you see, step on over to Housewife, Ph.D

Her content and comments are in purple; mine are in black.

ADHD 101 -

Attention Deficit Hyperactivity Disorder is a condition that affects impulsivity (the ability to control reactions/impulses), perseveration/task persistence, the ability to read social cues, and maturity. Teachers and school staff are likely to be the first people to notice these behaviors in young children. In the early 1900’s, the perception was that these behaviors were due to poor child-rearing. More recent research points to a combination or environmental agents, food additives, sugar, brain chemistry, and genetics as possible causes. ADHD is also tentatively considered to be a dopamine linked disorder, similar to Parkinson's Disease. Lower levels of dopamine are common in children with ADHD. Dopamine is the chemical that activates the reward principle in our brains, helps with hormone release, and has ties to motor control. More discussion on causes can be found at psychcentral.com. Also, students with ADHD have slower – but normally developing brains (see here). This is why many teachers show some frustration with students and their impulsivity and social skills – it can be up to three years behind that of their same age peers. There do seem to be a lot of genetic ties – so you are more likely to be diagnosed if you have an ADHD family member. ADHD is a very commonly diagnosed disorder (at least one student in every classroom across the country), and boys are diagnosed with it more frequently than girls. More data and stats on diagnosis and prevalence can be found here.

What did the authors of this paper in Medicine & Science in Sports & Exercies find out about ADHD and exercise? 

This study was based on previous findings that aerobic activity works synergistically with medical therapy (methylphenidate AKA Concerta or Ritalin) for ADHD. Previous work had shown that while about 10%-30% of children with ADHD are not helped enough by medication, adding as little as 20 minutes daily of aerobic exercise in addition to the medication improved attention, cognitive symptoms, and social skills within 6 weeks. This study sought to further our understanding of these improvements by looking for normalization of brain function (measured by functional MRI brain scans) in children who were treated with exercise and medication for their ADHD.

For this study, researchers recruited 35 teenagers (13-18) with diagnosed ADHD who were not currently taking medication. They also recruited 15 normal teenagers. Teens were excluded from the study if they had any history of non-ADHD processing or emotional diagnoses including Axis I mental disorders (depression, bipolar, ODD, many others), history of head trauma, or intellectual disability; or if they had a history of substance abuse. The ADHD teens were then split into two different treatment groups: one group was given methylphenidate and exercise (exercise group), the other group was given methylphenidate and classes on interpersonal skills (education group). The normal teenagers formed the control group.

For both treatment groups methylphenidate was started at 10mg/day. Then based on each teen's response to the drug, the dose was increased over the first 4 weeks to as much as 40mg/day, and then held at that dose for the duration of the study (6 more weeks).

For the exercise group, exercise was done 3 days per week with the researchers. In these 90min sessions teens first warmed up, then did 60 min of aerobic exercise, and finished with a cool down. The aerobic exercise was running, jumping rope, or playing basketball with the goal of keeping each teen's heart rate over 120bpm for the full hour.

For the education group the teens attended 50min classes twice per week. The classes were intended to help teach skills kids with ADHD often struggle with, including how to make friends and how to pay attention. In both groups the exercise or education sessions were continued for 6 weeks (starting after the 4 week period for adjusting to methylphenidat) and overseen by a psychiatrist and a social worker.

The majority of the results of this study focus on a comparison between the two treatment groups after 0, 4,and 10 weeks (i.e. baseline, medication only, and medication + 6weeks of exercise/education). These comparisons were made two ways. First, by conducting a traditional symptom-based ADHD assessment. Severity of symptoms is expressed with a numeric value. A higher number represents more sever symptoms. Second, by having the teens take a Wisconsin Card Sorting test while undergoing an fMRI brain scan. This sorting test works by asking the participant match cards, but with a catch: the participant isn't told in advanced what the matching rules are, but they are told if a match is right or wrong after it's been made. This test is used by researchers and psychiatrists to measure frontal lobe function: strategic planning, organized searching, using feedback, directing behavior toward achieving a goal, and modulating impulsive responding. All things kids with ADHD struggle with. Therefor, an improvement in performance on the sorting test suggests an improvement in ADHD symptoms. Performance can be measured in total time to complete the test or in the number of times the participant tries to use the same incorrect sorting rule (called preservative errors: in psychology "preservative" refers to failing to update behavior based on feedback).

At baseline both ADHD groups had an average symptom severity score of about 25, the control group had and average score of 4 (difference is statistically significant, p-value <0.01). Both ADHD groups had a non-statistically significantly longer time to complete the sorting test compared to the control (46.0 vs 33.6, p-value 0.06), and a statistically significantly larger number of preservative error (13.3 vs 8.1, p-value <0.01).

After 10 weeks both groups of ADHD teens showed improvement in their symptoms and in performance on the sorting test. For the exercise group their new average ADHD assessment score was 9.4, and for the education group it was 14.9. Both groups showed a statistically significant improvement over baseline, and the exercise group showed statistically significantly more improvement than the education group. The researchers do not say if the 9.4 score is statistically significantly different from the 4 for the control group; I suspect that it is (if it was statistically non-significant I think they would point this out as it would mean the exercise teens were "cured"). When looking at their sorting card tests the change in preservative errors showed the same pattern: both groups showed improvement, but the improvement was statistically significantly greater in the exercise group (baseline 13.3 errors, 10wk exercise 7.8, and 10wk education 11.1). In this case the exercise group appears to have achieved "normal" compared to the control teens (8.1 errors). These results were all consistent with previous findings that exercise improves ADHD symptoms.

This research wanted to answer an additional question: did the brain function normalize along with the symptom relief? Many parts of the ADHD teens brain showed less activity during the sorting test compared to the normal teens: right occipital lobe (vision processing), middle temporal gyri (image recognition/memory), right cerebellum posterior lobe (fine motor coordination), right prefrontal cortex (planning/focus/impulse control), right and left parietal lobes (sensory integration). The right limbic lobe (memory) showed more activity in the ADHD teens. One might imagine, based on this, that these teens are struggling to focus on the task at hand (more memory in use, less actual looking at / dealing with the cards).

After the 10 week intervention statistically significant changes in brain activity were seen. For the education group, changes were only seen in the right prefrontal cortex (planning/impulse control) and left parietal lobe (sensory integration). For the exercise group, changes were seen in those two areas and in the right middle temporal gyrus (but not left; image recognition/memory). The changes in activity withing the right prefrontal cortex (planning/focus/impulse control) were statistically significantly negatively correlated with change in the severity of ADHD symptoms and the number of preservative errors. Because this area was less active in ADHD teens, this means that as activity rose (towards normal levels), ADHD symptoms improved.

Based on these findings and the work of other researcher, this paper's authors conclude that aerobic exercise, when combined with medication, improved ADHD symptoms by increasing activity in the prefrontal cortex (planning/focus/impulse control) towards the levels seen in normal teens. Specifically, while they have not found a conclusive mechanism for this increased activity, they hypothesize that it may be related to increased dopamine and oxygenation/cellular metabolism due to better blood flow. The authors say that their study is limited because they did not include exercise only and education only (no medication) groups, so they cannot determine if the effects of exercise are synergistic or additive. They suggest further research to make this determination and see if specific types of exercise are more helpful.

What are our conclusions?

If you examine the criteria used to select/eliminate test subjects, the researchers did an excellent job eliminating co-morbid issues as well as blocking individuals on non-prescribed drugs. The study size ended up being small. Additionally, the study shrank more as subjects had negative reactions to medications and were unable to work out daily and were disqualified (more on that later). The scanning of the brains of the subjects showed what areas of the brain changed after the application of the treatments (exercise showed the best results)--and it was the prefrontal cortex! This is a GREAT outcome. Dopamine is likely a key player in the change as exercise helps to raise dopamine levels! Don’t we all love some dopamine?

Here’s where we get to my more specific questions/concerns. Accepting the science at face value and assuming a larger study would have similar results – I am still not sure how practical the findings of this study are. In as school setting, we have no influence over (and should not suggest) putting students on medication to begin with. We can comment if we’ve seen changes from a child’s dosage changes, but medical decisions are family business. This study started with the subjects all being medicated. Medication does work for some, but I know it does not work in all situations (from personal experience as well as observations). Additionally, the amount of exercise in the test group totaled about 80 minutes a day 3 days a week. Not only was this a larger quantity of time then the soft skills lessons, it is a large block of time for many busy high school students. It would eliminate time for after school tutoring, organized sports, and outside pursuits.

For research-motivated special educators and parents, this study confirms what years of anecdotal evidence have suggested. Kids need to move. People need to move. Aerobic activity helps immensely with focus and helps speed up the lagging prefrontal cortex development. Exercise is something I heartily endorse at meetings and in forming plans for students. It is also an opportunity for parents and students to take ownership of the student’s educational progression. If running, swimming, or basketball is going to help your child succeed, steps need to be taken to make that a priority on the family level. Schools can provide some outlets through team sports/ROTC/PE, but cannot bear the full responsibility. A team sport could provide some of the suggested aerobic activity, such as soccer or cross-country. I will be reading more studies focusing on shorter sessions of aerobic activity or less days of training a week and seeing if the results are similar. Traditionally, team sports are considered to be an excellent way to grow social skills – perhaps it is because of the dopamine and those little blossoming prefrontal cortexes!

It is important here to remember that while schools are mandated to provide learning opportunities to all students, we are also bound to provide all students free and appropriate education and equal access. Equal access does not necessarily mean providing every conceivable resource. So while I think adding more movement at every level would be beneficial for ADHD (and possibly all!) students, it would take a major overhaul of schedules, student expectations, massive amounts of funding and a huge amount of parental support and effort to have movement classes tacked on or added to a school day. I think this is a situations where individual parents and families have a lot of power in enabling their students by encouraging a school sport, or even just buying their child some running shoes. Policy changes won't happen overnight - if this is a direction parents want to see our schools going, we need to hear from them!

I mostly agree with everything said here, but I think that there are policy changes that schools can make that will be good for all kids, and it sounds like particularly good for kids with ADHD. Sara-Liz said, and I 100% agree, kids (people) need to move their bodies. At its very simplest, let's get recess and PE (and art, music, and drama!) into all schools. Especially elementary and middle schools. More time for math and science sounds great (especially to me), but if the kids can't focus because they need to wiggle then it doesn't benefit them and may just make them hate the subjects or think they're bad at them. These aren't changes that one (special ed) teacher can institute; these are changes that need to be made at the district or state level. So while a parent can (and should) make sure his/her child gets the chance to run and move and play outside of school hours, maybe parents of kids in schools with no recess should also start talking about this kind of research with the people who can change school policies/schedules. Adding more "stuff" to the schools' list of responsibilities isn't an easy fix, it's complicated and expensive. And, of course, making time for recess won't force kids to get their heart rates up--the schools can't and shouldn't do that. But we have public school so that every kid has the opportunity to learn, grow, and succeed. If more research continues to find that movement and time outside is important to kids' development, then the effort and expense to ensure all kids have access to some supervised safe outdoor play time will be money well spent. 

References (paywall)

Choi, JW. et al. "Aerobic Exercise and Attention Deficit Hyperactivity Disorder: Brain Research" Medicine & Science in Sports & Exercise. Published ahead of print April 2014. Accessed Nov 5, 2014.