Measuring Autism: A Problem of Epidemic Proportions

Tina Dyches

Autism spectrum disorder is now diagnosed in 1 in 91 children (1 in 58 boys), according to the Center for Disease Control. Tina Dyches presented this startling statistic to students and faculty gathered at the Educational Inquiry, Measurement, and Evaluation (EIME) seminar. Many refer to this as an autism epidemic, but in her seminar presentation Dyches posed a relevant question: “Is it a measurement issue?”

Dyches, a professor in the Department of Counseling Psychology and Special Education, explained that autism spectrum is a large umbrella under which there are five disorders: autism, Apserger syndrome, Rett’s syndrome, childhood disintegrative disorder, and PDD-Not Otherwise Specified (a diagnosis for children who may exhibit traits of the autism disorders but do not meet the qualifications to be classified in any one of them).

Guidelines have been established to diagnose children with any of the five disorders on the autism spectrum. For example, a child with autism must exhibit at least two symptoms in the category of social interaction, nonverbal behaviors, peer relationships, or social-emotional reciprocity; at least one symptom in communication; and at least one pattern of disordered behavior, abnormal preoccupations, inflexible adherence to routines, or repetitive motor mannerisms. However, even if the system of diagnosis appears clear and specific on the surface, the reality is that diagnosing children on the autism spectrum is extremely complex.

According to Dyches, the spectrum of autism disorders is huge, and behavior and development vary considerably among individuals diagnosed on this spectrum. Sometimes children with autism are misdiagnosed as having mental retardation. “Just because a child is non-verbal and non-social does not mean he could not have a gifted IQ,” Dyches told students and faculty. “We have at least seven students along the autism spectrum here at BYU.” Dyches shared a few videos on YouTube showing examples of different functionality levels along the autism spectrum, including a professor’s guide to teaching college students with autism.

A high functioning disorder on the autism spectrum is Asperger syndrome. One of the factors that distinguishes Asperger from autism is normal early language development. A common trait among individuals with Asperger syndrome is a significant challenge in understanding nonverbal behavior or social nuances.

In addition to the wide variety on the autism spectrum, researchers’ ability to measure autism is affected by changes in the way autism is reported. Autism was not recognized in the schools as a specific disability until 1990. In 1992, the Individuals with Disabilities Education Act (IDEA) required that autism be reported as a separate category from other disorders. As a result, the rate of autism reported among children increased suddenly. In 2000, researchers started investigating the different categories of autism along the autism spectrum and began distinguishing them in reporting.

These changes in reporting likely influenced the following statistics reported in a recent study conducted in Utah. The study found a 110% increase per year in autism in Utah, with increase rates of 17.5% for mental retardation, 12.6% for epilepsy, and 12.4% for cerebral palsy.

In her presentation, Dyches identified the following as primary problems in measuring autism:

 

 

 

 

  1. Changes in definition

     

     

     

     

     

     

     

     

    1. Changes over time
    2. Diagnostic substitution or accretion

     

 

Substitution: individuals originally diagnosed as having one disability and later diagnosed differently

Accretion:  individuals originally diagnosed as having one disability and later receiving an additional diagnosis

 

 

 

 

 

 

  1. Variable Methods of Diagnosing--diagnosis based on an observational behavioral checklist and expert assessment is imprecise
  2. Variable Research Methodologies--epidemiological data differ from educational surveillance data

Autism has no single biological marker, and variability in diagnosis depends on the assessment tools used. In recent years diagnosis of autism has increased with younger children and older individuals. Infants are now being diagnosed with autism as early as 12 months.

Variation in  research methodologies makes it difficult to accurately diagnose autism. In a recent study, surveyors took all the medical records and school administration records for Utah children ages 5-18 to determine the prevalence of autism in the state. This method differs from another study where researchers phoned parents and asked the question “Has [a randomly selected child] ever been told he has an autistic disorder?” Critical questions of this study included the following: How was the child randomly identified?  Did a doctor or a health care provider diagnose the child? Dyches concluded that the second study is very imprecise but is getting a lot of attention in the media. “Be careful of what you see on TV,” Dyches warned. “Look at the research methodology.”

In response to the Center for Disease Control Deputy calling autism a serious epidemic, Dyches said, “We don’t know if autism has increased or decreased because we lack a design to measure it.” She identified additional possible causes for the apparent increase in autism such as research methods and social factors including increased awareness, reduced stigma, and financial incentives such as insurance.

Dyches suggests that future research should control variables, standardize case findings, use consistent methods, and include data such as race, IQ, social class, and education. In her research of autism, Dyches has learned that Hispanic populations are largely under diagnosed while the Asian populations are over-identified, which affects the educational services and accommodations made available to students in these populations.

23 November 2009