Many educators and parents might expect that students with dyslexia will have a more difficult time reading if they also have Attention-Deficit/Hyperactivity Disorder (ADHD), and that the frequent co-existence of the two neurological disorders must be connected. But preliminary research findings co-led by an MGH Institute researcher show it may actually be caused by executive function (EF) deficits. 

To try to solve this puzzle the National Institute of Health has awarded a five-year R01 grant to a team led by Dr. Joanna Christodoulou, Director of the Institute’s Brain, Education & Mind (BEAM) Lab, that will take an in-depth look at whether a student with dyslexia is impacted when reading by ADHD, EF challenges, or both. The $3,875,958 award is the third largest in IHP history and represents the nation’s largest and longest neurocognitive study of dyslexia to date. 

Dyslexia and ADHD are neurodevelopmental disorders with a high rate of existing simultaneously (an estimated 40% co-occurrence rate). While EF challenges are common in both disorders, examining EF in dyslexia with ADHD and dyslexia without ADHD is an under-studied topic, Christodoulou noted. The grant could uncover whether EF deficits, ADHD, or both may prevent some students with dyslexia from closing gaps in reading performance.  

“It was a surprise to learn that ADHD and executive function are not synonymous,” said Christodoulou, who is the principal investigator for the grant, about the preliminary findings. “Not everyone with executive function challenges has ADHD and not everybody with ADHD has executive function challenges. We find about half of students with ADHD also show EF deficits, in line with previous work. That debunks a lot of the common thinking around what ADHD is for many people. The second finding was that you're not necessarily performing better or worse as a reader if you have dyslexia with co-occurring ADHD but having higher or lower EF does differentiate reading performance among readers with dyslexia (our third finding). So, EF matters more than an ADHD diagnosis for understanding what kind of reading struggles students are going to have.”

The preliminary study utilized brain imaging and reading tests from 80 students. Christodoulou and collaborators Dr. John Gabrieli, cognitive neuroscientist at MIT, and Drs. Ellen Braaten and Alysa Doyle, clinicians from the Learning & Emotional Assessment (LEAP) Program at Massachusetts General Hospital, published these findings in the journal Cortex

The team’s longitudinal study will utilize annual brain scans of third- and fourth-grade students over three years to determine how reading, ADHD status, and executive function are intertwined over time. This study will be like the one in Cortex, but it will be longer, broader, and will enroll over 350 students including typically developing readers, students with dyslexia, and students with dyslexia and ADHD. 
The team expects to find support for the following hypotheses: 

  • Among children with dyslexia (with and without ADHD), EF deficits - but not ADHD diagnosis - will be associated with more reading challenges
  • Children with dyslexia who don’t have EF deficits will demonstrate more reading growth than peers with EF deficits, regardless of ADHD status
  • EF deficits will impact reading fluency, but not reading accuracy performance and growth

“There are a lot of assumptions that ADHD will make your reading worse, partly because you're not paying attention, partly because you might have some bottlenecks in your thinking process,” Christodoulou said. “Because there's such a bright spotlight on ADHD, it can be to the detriment of looking at other reasons that might be underlying reading difficulties.

“Our finding that executive function actually matters more for literacy means that as a teacher, you can be conscientious about the ways in which you're either accommodating EF during reading instruction, or you’re giving students strategies to optimize the skills that they already have.” 

She says the findings can inform school-based approaches for assessment and instruction, for example, by measuring EF skills in addition to reading skills among struggling students, being tuned to red flags that accompany EF deficits, such as difficulties with processing speed or working memory, considering the burden of different reading activities on EF skills, and integrating effective strategies for students to manage EF challenges. 

“If I know it takes a student just a little longer for information to sink in (i.e., processing speed challenges), then as an educator I know I need to chunk information and make material more accessible in smaller portions. I need to check in and make sure they're still with me, I need to give them a chance to process all this information and give it a chance to go through all the cogs so they can learn it better.”

Christodoulou and her team will be recruiting participants for this research. If you would like to be contacted for study participation, please beamstudies [at] (email the Brain, Education, and Mind (BEAM) Lab)title="Link to email to contact the BEAM Lab".