What are the differences and similarities between Non-Verbal Learning Disabilities (NVLD) and ADHD?

The following question was received during the LD@school webinar, Understanding Non-Verbal Learning Disabilities: From Diagnosis to Interventionclick here to view the webinar recording.

Answered by Dr. Allyson Harrison, Associate Professor of Psychology and Clinical Director of the Regional Assessment & Resource Centre, Queen’s University

I know that you said many of the signs of NVLD are the same as ADHD, but can a child have both? Is there a correlation between NVLD and ADHD?

Great question. When I first started researching children with non-verbal learning disabilities (NVLD) and was trying to recruit students for my studies, teachers (and parents) often nominated students in their classes who were struggling with math. What I quickly began to realize was that, while many of these nominated children did indeed struggle with math, for almost all of them it was due to attention deficit hyperactivity disorder (ADHD) rather than NVLD. While the visible problem (struggling with math, getting poor grades in math) may look the same, the cause of their problems was very different.

To learn more about the characteristics of NVLD and how it is diagnosed, click here to view the LD@school webinar, Understanding Non-Verbal Learning Disabilities: From Diagnosis to Intervention. To read the definitions of NVLD and ADHD, click here to access LD@schools Glossary of Terms.

While it is theoretically possible to have someone who has both NVLD and ADHD, these two conditions often get confused because some of the symptoms associated with them overlap. This does not mean that the two conditions are co-morbid (that is, it is not the case that they frequently occur together), but rather that some of the symptoms of both conditions look the same. It is sort of like saying that just because two people have a high fever does not mean they have the same diagnosis.

What I often tell parents and teachers is that students with a learning disability (LD), including NVLD, struggle to learn certain types of information, and will consistently find certain types of learning difficult. As such, someone with NVLD will struggle in math every day, in every class, with every teacher. By contrast, individuals with ADHD are often “unavailable” for learning. What you typically see in the academic histories of these students is that in one year they do all right in their schoolwork, and yet in the next year they struggle. One teacher has positive things to say, while the other criticizes their learning behaviours and academic performance. Typically, students with ADHD will say that they did better in one course than the other because they liked the teacher better or that the teacher was more engaging. While students with NVLD may like one teacher better than another, this does not typically change how they perform in their area of academic weakness.

In math, one has to be careful to correctly read symbols, as they can look similar. Typically, students with ADHD have difficulty in math because of what are often called “careless” errors. They misread  + for x, or a division sign as a minus. They rush and forget to insert a period or a zero in an answer; they invert number order, reading 23 instead of 32. If you probe afterwards, you usually find that they knew the answer but made a mistake. These students usually understand general mathematical principles, they just don’t always remember when and how to apply them.

By contrast, those with NVLD struggle to learn not only basic math but applied mathematical principles such as bigger than/less than, half/quarter/double, estimating size/distance, etc.

The other thing to remember is that those with NVLD are great at rote memorization. Hence, if you teach them their times tables they will remember them and be able to recite them easily (but may not always know when to apply them out of context). By contrast, students with ADHD often struggle with working memory tasks, and so find mental arithmetic problem solving difficult. I find that these students often struggle to learn their times tables, and benefit from learning tricks to remember them, such as the finger counting method for the 9 times table (click here to see a video explaining this method). However, once they can see the problem written down, and can offload the working memory demands onto paper, they perform much better in math.

If your students have trouble retaining math facts and keeping procedures in the proper order, click here to access the LD@School article, Math Heuristics.

It is also true that both students with NVLD and many students with ADHD struggle with fine motor skills such as handwriting. As such, at least in childhood, individuals with both conditions can indeed look similar. The difference is that often those with ADHD are good at more gross-motor activities and sports, whereas those with NVLD struggle initially with most motor activities, including sports.

Click here to access the LD@schol article, Strategies to Develop Handwriting and Improve Literacy Skills.

Finally, individuals with both disorders can struggle with attention and organization. Those with NVLD struggle in situations where they have to integrate and understand complex information, and have trouble knowing where or how to start novel or complex tasks. Those with ADHD have similar difficulties, but can focus on tasks that are exciting (even if complex), and can organize if they are motivated and interested. For those with NVLD, level of interest and/or motivation does not change their ability to focus or organize.

Remember, NVLD is actually very rare, rarer than ADHD. So, to have someone with both NVLD and ADHD is extremely rare. To meet the diagnostic criteria for NVLD, an individual has to have not only a math disability (problem not just with math calculation but with understanding of math concepts), but must also show a number of neurological deficits that include fine motor impairment, difficulty recognizing shapes based on how they feel or their physical properties, and find it consistently difficult to read body language or non-verbal cues. Visual memory skills are always weak, whereas they tend to have good verbal memory. They must consistently struggle with math, not just sometimes or with some types of math. Finally, while they tend to have a huge vocabulary, they struggle with reading comprehension, especially when they have to read between the lines and infer from the text. Click here to access teaching strategies for inferential comprehension, created by the government of New South Wales, Australia. This “whole package of deficits” is not what you find in students with ADHD.

About the Author:

Dr. Allyson Harrison received her Ph.D. in psychology from Queens University, Kingston, in 1992. She is currently the Clinical Director of the Regional Assessment & Resource Centre at Queen’s University, a government funded program that provides Psychological assessments to postsecondary students Province-wide. In addition, she holds an appointment as an Associate professor in the department of Clinical Psychology at Queen’s. Over and above her clinical practice, she has been active both nationally and internationally, providing continuing education on issues related to LDs and ADHD. Her areas of research interest are in assessment and differential diagnosis of LD and ADHD, and she has published over a dozen articles in peer-reviewed journals. She is also a member of the editorial board of the Canadian Journal of School Psychology, Journal of Psychoeducational Assessment, and The Clinical Neuropsychologist.

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