Topic 2: Diagnosis: What Do We Know?

If you are interested in learning more about the diagnostic process, click here.

Parents of children with autism will often express concern when their children are about 18-24 months old, but it can take time to get a diagnosis of ASD. Parents of children with autism also report having concerns about their children's vision and hearing during their first year, and report differences in social, communication, and fine motor skills from about 6 months old on. The average age of diagnosis in the United States is about 4 years old. This is based usually on the fact that children are being referred for diagnostic evaluation around that age. A study by Zuckerman, Lindly, and Sinche published in The Journal of Pediatrics in 2015 showed that doctors were less likely to respond to parents' early concerns that their children may have ASD, delaying diagnosis by an average of 2.7 years. However, current screening and diagnostic tools, like the ADOS-G, can detect ASD when children are 24 months old or younger.

While a multidisciplinary team is not always needed to diagnose a child with autism, it can be helpful for planning a child's treatment. In 2014, the American Academy of Child and Adolescent Psychiatry released new recommendations for treating autism. One of the recommendations calls for a child's doctor to coordinate a multidisciplinary team of specialists to assess the child to help make treatment recommendations. These teams can include psychologists, speech and language pathologists, and occupational and physical therapists, as well as pediatricians. Genetic testing may also be helpful in some cases to identify genetic abnormalities such as Fragile-X syndrome, which can have features similar to autism. Treatment plans created by multidisciplinary teams can make sure a child with autism receives "whole-person" care.

There are often many other diagnoses before ASD. In 2015 Miodovnik, Harstad, Sideridis, and Huntington analyzed the 2011-2012 National Survey of Children's Health and found that 20% of children who had been diagnosed with ASD had initially been diagnosed with ADHD. The same study found that an initial diagnosis of ADHD delayed the children's diagnosis of ASD by about 3 years and these children were about 30 times more likely to be diagnosed with ASD after they were 6 years old. As you'll learn below, a diagnosis of ASD does not rule out other comorbid conditions like ADHD, intellectual disabilities, and anxiety disorders. Some of these have symptoms that may mask the underlying ASD.

As you learned in Topic 1, autism is more common in boys than girls. A 2016 study by Christensen et. al. in MMWR Surveillance Summaries found that autism had a prevalence rate of 1 in 42 among 8-year-old boys, but a prevalence rate of 1 in 189 among 8-year-old girls. A 2013 study by Donna Werling and Daniel Geschwind in Current Opinion in Neurology found that there is a possibility that some of the differences in these diagnostic rates are social (males are more likely to be referred for diagnosis) or that ASD presents differently in females (males are more likely to present with disruptive behaviors like hyperactivity and aggression).

Comorbid Conditions 

People who have more than one distinct medical condition at the same time have comorbid conditions. Autism Speaks states in its 2017 report Autism and health: A special report by Autism Speaks: Advances in understanding and treating the health conditions that frequently accompany autism that people with autism often have at least one other comorbid condition. These conditions can affect both the mental and physical health of a person with autism, and are significantly more likely to occur in adults with autism than adults without autism. To learn more about these comorbid conditions, click here.

Activity: Read the statements below about diagnosing autism and decide true or false.

References

Christensen, D. L., Baio, J., Braun, K. V., et al. (2016). Prevalence and Characteristics of Autism Spectrum Disorder Among Children Aged 8 Years - Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2012. MMWR Surveillance Summaries 65(3), 1–23. DOI: http://dx.doi.org/10.15585/mmwr.ss6503a1.

Miodovnik, A., Harstad, E., Sideridis, G., & Huntington, N. (2015). Timing of the diagnosis of attention-deficit/hyperactivity disorder and Autism Spectrum Disorder. Pediatrics 136(4). Retrieved from http://pediatrics.aappublications.org/content/136/4/e830.

Volkmar, F., Siegel, M., Woodbury-Smith, M., King, B., McCracken, J., State, M. & American Academy of Child and Adolescent Psychiatry. (2014). Practice parameter for the assessment and treatment of children and adolescents with Autism Spectrum Disorder. Journal of the American Academy of Child & Adolescent Psychiatry 53(2), 237-257. doi: http://dx.doi.org/10.1016/j.jaac.2013.10.013.

Zuckerman, K. E., Lindly, O. J., & Sinche, B. K. (2015). Parental concerns, provider response, and timeliness of Autism Spectrum Disorder diagnosis. The Journal of Pediatrics 166(6), 1431-1439. doi: http://dx.doi.org/10.1016/j.jpeds.2015.03.007.