Untangling Attention Difficulties in Autism


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Benjamin Yerys, PhD, is a psychologist trying to unravel a problem that, up until a few years ago, did not officially exist. Prior to the publication of the most recent fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the official party line among mental health professionals was that a child who had autism spectrum disorder (ASD) could not also have attention-deficit/hyperactivity disorder (ADHD).

“They would just say, ‘Well, the autism spectrum is just really wide. That’s not really ADHD. That’s autism,’” Dr. Yerys recalled of the presiding sentiment at that time.

But Dr. Yerys, a researcher in the Center for Autism Research at Children’s Hospital of Philadelphia and assistant professor at the Perelman School of Medicine at the University of Pennsylvania, had seen in his clinical practice and research that many children with autism really do have attention problems distinct from their ASD-related behaviors, years before the DSM-5 task force ultimately came to agree.

Now, children can and do have diagnoses of both ADHD and ASD. They account for about 30 percent of children with an ASD diagnosis, and there is an added problem in these tangled cases: “We’re doing a much poorer job treating ADHD in kids with autism compared to other kids with just ADHD,” Dr. Yerys said. “I want to understand why that’s the case.”

Research on treatments of attention symptoms, whether with stimulants including methylphenidate (Ritalin®) or non-stimulant medications, shows that these treatments have relatively high response rates among children with ADHD in the general population and relatively low incidence of severe side effects. Among children with ASD, response rates to ADHD treatments are much lower, while side effects occur much more often.

To get at the question of why that is and what can be done to better help children with both ASD and attention problems, Dr. Yerys and colleagues at CAR pursued research to see if ADHD was even being measured correctly in children on the autism spectrum. Inaccurate measurements — such as misdiagnoses of ADHD in some children with ASD — could explain why the treatments work poorly in so many of these children. They are simply the wrong treatments.

To ask these questions, Dr. Yerys worked with a colleague who created one of the most widely used tools for diagnosing ADHD in the general population. Thomas Power, PhD, director of CHOP’s Center for Management of ADHD, co-developed the ADHD Rating Scale Fourth Edition (ADHD-RS-IV) in the 1990s. This is a well validated tool that asks parents and teachers to provide numerical ratings in reply to 18 items about a child’s behavior: nine items on inattention and nine on hyperactivity and impulsivity. Testing the rating scale across a wider population of children with ASD, the researchers found that some questions about inattention and one about hyperactivity were poorly related to the other questions of inattention and hyperactivity/impulsivity, respectively. While this finding does not negate the usefulness of the tool for identifying ADHD symptoms in some children with ASD, it shows that it is flawed when used in children with ASD and potentially too sensitive to behavioral differences in this group that do not actually reflect ADHD. The findings were published in the Journal of Autism and Developmental Disorders.

“We’ve learned from this that maybe we need to be a little more careful in making an ADHD diagnosis,” Dr. Yerys said. “Even specialists need to step back and do a little bit more careful interviewing to make sure that when a parent says, ‘Yes, my child is easily distracted,’ is that really about being just distracted?”

Until more effective diagnostic tools are developed for this population, clinicians should consider the circumstances of a child’s reported behavior to distinguish the possible contribution of autism-related differences, he noted. His hypothesis is that social differences related to autism might be misinterpreted as signs of ADHD if the social component of behaviors are not taken into account. Does the child fail to stay focused on a topic of conversation with others because he is easily distracted, or is he simply not attuned to the social conventions of taking turns speaking and engaging in another person’s interests?

Dr. Yerys and colleagues, including Dr. Power and CAR director Robert Schultz, PhD, hope to pursue further research to confirm this hypothesis. They also hope to interview parents about what behaviors are typical in children with both ADHD and ASD to establish better questions to differentiate this subgroup from children with only ASD using an improved diagnostic test.

“I’m excited to be involved in this study, and in efforts to refine our screening tools for ADHD among various populations of children,” said Dr. Power, who is also associate chief of academic affairs in the department of Child and Adolescent Psychiatry and Behavioral Sciences at CHOP and a professor of School Psychology in Pediatrics and Psychiatry at the Perelman School of Medicine at Penn.  “This study makes a unique contribution because few researchers have previously investigated the use of rating scales for ADHD among children with ASD. Our research raises questions not only about this assessment tool, but all such measures that rely on parent and teacher ratings to assess ADHD in children with ASD.”

In addition to working to improve diagnostic tools, Dr. Yerys is pursuing a separate line of research also aiming to help this population. Using brain imaging tools, he is trying to learn if attention problems in children with ASD have the same underlying biological causes as they do in children with only ADHD. A different underlying biological cause could help explain why ADHD medications seem not to work as well in the ASD population. At the same time, any new insights about the biological causes of attention problems in ASD could point to what different treatments might work better in this group.

“The biggest problem we have in all of psychiatry, not just autism, is that when a treatment doesn’t work, we don’t know why,” Dr. Yerys said. “We hope to know which treatment is the right treatment for someone. That’s the whole idea behind personalized medicine, and that’s really where this line of research is headed.”

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