A new study, published in the Journal of Autism and Developmental Disorders, suggests that symptoms of autism spectrum disorder (ASD) in children may be falsely identified as being symptoms of attention deficit/hyperactivity disorder (ADHD) by common diagnostic measures. This overlap could lead to children with ASD receiving an additional diagnosis of ADHD despite having no additional symptoms.
The researchers state that “ADHD symptoms of ‘Is easily distracted,’ ‘Has difficulty sustaining attention to activities or play,’ or ‘Does not seem to listen when spoken to directly’ may be observed by a caregiver or a teacher because the individual is inattentive or hyperactive/impulsive, or because the youth with ASD lacks social skills to engage and disengage from an interaction appropriately.” Because these symptoms appear in both cases, they could be identified by an ADHD questionnaire despite being associated with symptoms of ASD.
The researchers used the ADHD Rating Scale—Fourth Edition (ADHD-RS-IV) for their study because it includes all the criteria for making an ADHD diagnosis, unlike other measures (such as the Child Behavior Checklist). This rating scale is used for determining whether a child may qualify for school supports and what treatment options are available, making the tool’s validity of increased importance.
The participants were 386 children between the ages of 6 and 17 who met criteria for autism, Asperger’s syndrome, or pervasive developmental disorder not otherwise specified. Their caregivers and/or teachers answered the questions on the ADHD-RS-IV. The researchers note that their study excluded children with major cognitive impairments, so it is unclear whether their results would hold true for that population.
Their results indicate that there is significant overlap between ADHD symptoms and autism spectrum disorder symptoms, particularly as measured by the ADHD-RS-IV. They attempted several statistical models of the data, and the ADHD-RS-IV failed their validity test. The researchers state that “the scale does not adequately separate the constructs of inattention and hyperactivity/impulsivity in ASD.” They described it as an “unacceptable fit.”
According to the researchers, diagnosing ADHD in children with ASD only became possible in 2013, when the fifth edition of the Diagnostic and Statistical Manual of Psychiatric Disorders (DSM-5) was published. The previous edition did not permit both diagnoses together, but the new edition does. Other researchers have raised numerous concerns about the over-diagnosis of ADHD in children and criticized the many changes in the DSM-5 as promoting over-diagnosis and overmedication.
A study published in PLoS Medicine revealed that 78% of the individuals on the panel revising the diagnostic guidelines for ADHD had ties to the pharmaceutical industry. Additionally, concerns about the subjectivity of the ADHD diagnosis have been supported by researching finding that the youngest children in a kindergarten class were consistently more likely to receive an ADHD diagnosis and be prescribed stimulants.
The researchers state that the rating scales for ADHD need to be revised, with wording that will make clear the distinction between ASD symptoms and ADHD symptoms. Until this happens, providers need to be aware that using the current wording could lead to over-diagnosis of ADHD in children with ASD, and conduct additional clinical interviews to ensure accuracy in diagnosis.
Yerys, B. E., Nissley-Tsiopinis, J., de Marchena, A., Watkins, M. W., Antezana, L., Power, T. J., & Schultz, R. T. (2016). Evaluation of the ADHD Rating Scale in youth with autism. Journal of Autism and Developmental Disorders. doi: 10.1007/s10803-016-2933-z (Abstract)