ADHD and Asperger's

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By Liji Thomas, MDReviewed by Jonas Wilson, MD, Ing. Med.

Attention deficit hyperactivity disorder (ADHD) and Asperger’s disorder were considered to be two distinct psychiatric conditions.

Asperger’s disorder, like other conditions in the autism spectrum, is characterized by significant lack of social interaction, communication, and limited behavior patterns, with seriously restricted interests and activities. However, it is now considered to be the same condition as autism, albeit on a much milder level, giving it the name ‘high-functioning autism’ (HFA).

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The term Asperger’s itself, as a separate entity from autism, is under scrutiny as it appears to be just one end of the spectrum of autism spectrum disorders (ASD). The only difference between them is one of symptom severity rather than symptom type. Diagnostic criteria for both closely resemble each other and the diagnosis is easily replicated by other providers.

In the DSM-IV, ADHD could not be diagnosed in a child already known to have any of the ASDs. However, this has been corrected in the DSM-5 in response to the many studies that have shown that they have many overlapping features. Depending on the study, rates of comorbidity have been reported to vary from 14-78%, with many aspects of study reflecting a basic linkage between the two conditions.

Deficits in ADHD vs. Asperger’s

Deficits in plain ASD are usually associated with planning and having flexibility of thinking to adapt to changing demands to get a task done. ADHD on the other hand poses difficulties to do with inhibition deficits along with problems in sustaining attention long enough to execute complex tasks. However, children who have ASD, but also display symptoms of ADHD, have more difficulty with inhibition than those who do not have attention deficits. In short, children with ASD often have symptoms of ADHD.

At the same time, the two conditions may differ significantly with respect to the area of cognition affected. One study went into the specific deficit among the areas of verbal working memory, acquisition of data, and delayed recall in children with Asperger’s, children with ADHD, and typical children. It turned out that children with Asperger’s and those who had ADHD performed both equally and poorly in all three areas, compared to typical children.

However, within the Asperger’s group they found that some had associated attention deficit, and these had worse results than those without impaired attention. They concluded that these represented two different categories of cognitive dysfunction.

Neuroimaging and psychopathological studies show that both of these are defects of neural development involving the executive functions of the brain, chiefly the networks connecting the frontal cortex with the striatal and parietal parts of the brain for the ADHD and Asperger’s affected children, respectively. The associations between them are supported by emerging genetic studies as well.

Conclusion

The importance of this finding is the therapeutic benefit of knowing how children with Asperger’s and ADHD will respond to traditional modalities of treatment, and modifying them appropriately to optimize the response. For instance, training children with Asperger’s in social skill development is a crucial part of early intervention.

However, this may be much more difficult in the presence of associated ADHD, which makes the execution of sequential, carefully executed maneuvers impossible. This is because the child does not maintain focus or take turns in the planned social interaction, due to impulsive and hyperactive behavioral patterns.