Did you know that October is ADHD Awareness Month and Dyslexia Awareness Month? Surprise! In truth, this overlap makes a lot of sense, as ADHD and dyslexia frequently co-occur. Read on to learn more!
What is Dyslexia?
Throughout the world, the term “dyslexia” is often used to refer to a range of reading difficulties. Diagnostically, however, “dyslexia” refers to a particular subset of reading difficulties under the category of a Specific Learning Disorder. The Diagnostic and Statistical Manual of Mental Disorders - Fifth Edition (DSM-5) defines Specific Learning Disorders as neurodevelopmental disorders that are:
typically diagnosed in early school-aged children
characterized by persistent impairment in at least one of three major areas (reading, written expression, and/or math)
not due to other factors (e.g., intellectual disability, chronic absenteeism, limited proficiency in the language of instruction, or limited instruction or intervention)
Individuals diagnosed with a Specific Learning Disorder with Impairment in Reading may struggle with one or more of the following skills:
word reading accuracy, or the ability to recall sight words from memory
phonetic decoding accuracy, or the ability to sound out words using letter sound knowledge
fluency, or the ability to read with accuracy, speed, & expression
comprehension, or the ability to make meaning from written material
Some individuals only exhibit weaknesses in decoding or reading fluency, while some struggle across the board. For those individuals with substantial difficulties in word reading accuracy and/or fluency, decoding, and spelling, the descriptor of dyslexia is used to denote this specific constellation of symptoms.
Side note: Today’s blog post is not a lesson in semantics. As diagnosticians, we understand the widespread use of the term “dyslexia” to describe a persistent breakdown somewhere within the reading process. Aside from the fact that “dyslexia” is a far more efficient way of saying “specific learning disorder with impairment in reading with weaknesses in…,” we know that parents of kids with reading difficulties (and kids themselves!) find community and resources through the use of this term. So for today’s blog post, we use the term “dyslexia” to refer to various difficulties associated with the reading process.
Comorbidity of ADHD & Dyslexia
While ADHD and dyslexia are distinct conditions, they often co-occur in the same individual. Research suggests that between 30 to 60% of individuals with ADHD also have a learning disability, the most common of which is a reading disorder. In fact, between 25 to 40% of individuals with dyslexia are diagnosed with ADHD and vice versa. While we don’t fully understand why these conditions frequently co-occur, we know both have substantial heritability.
Researchers from the University of Edinburgh recently identified 49 genetic regions and 174 genes shared between dyslexia and ADHD (with 40 regions and 121 genes not previously identified). These findings suggest that there may be common genetic roots for these two disorders. In fact, they found that ADHD and dyslexia share more genetic commonalities than any other psychiatric condition. You can dig into the full research article published in July 2024 by Molecular Psychiatry here.
Beyond the above study, diagnosticians, researchers, teachers, and interventionists have long observed shared challenges between ADHD and dyslexia, such as weaknesses in executive functioning (e.g., planning and organization), language processing, and working memory. We also know that the presence of ADHD can exacerbate dyslexia and vice versa, and that treating one condition doesn’t necessarily treat the other. For example, treating ADHD with stimulant medication may improve a child’s ability to sustain their attention in school, but stimulant medication won’t directly treat the child’s reading disorder.
Takeaway
ADHD and dyslexia have high comorbidity; people with ADHD are more likely to have reading difficulties, and children with dyslexia are more likely to have ADHD symptoms. If your child is struggling in one area, monitor the other. While the two disorders often co-occur, treating one disorder does not guarantee treatment of the other. Each condition must be addressed separately.
Given the high comorbidity of ADHD and learning disorders, we strongly encourage comprehensive psychoeducational evaluations whenever initial assessments are being considered. Such evaluations provide an in-depth assessment of an individual's cognitive functioning (e.g., reasoning, processing speed, memory), academic achievement, attention and executive functioning, and social/emotional well-being. Most importantly, comprehensive psychoeducational evaluations identify whether co-occurring conditions exist, and they provide guidance on how best to address each condition. Contact us to learn more!
Stay tuned for our next blog post, in which we'll explore the intersection of ADHD and dysgraphia.
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