Autism spectrum disorder (ASD) has been one of the most widely researched medical conditions in the United States in the past two decades. As awareness of ASD grew, debates over its causes garnered much attention. Claims that there was a link between childhood vaccinations and ASD fueled much of the debate. While research has not shown a link between vaccinations and ASD, there still is no definitive proof of a cause. However there is proof of an increase in the prevalence of diagnosed ASD.
The Centers for Disease Control and Prevention (CDC) has tracked ASD rates through biennial studies of eight-year-olds since 2000. Researchers examine the medical and school records of children, looking for actual diagnoses of ASD or reports of behavior that are likely to indicate ASD. During the time the studies have been conducted, the rate of ASD has dramatically and consistently increased. The first study in 2000 showed a rate of ASD of 1 in 150 children. The most recent study for which data is available is from 2016 and showed a rate of 1 in 54 children. Boys are approximately 4 times more likely than girls to be diagnosed with ASD, and ASD appears in all racial, ethnic, and socioeconomic groups.
The biggest factors in the rising rates of ASD among American children appear to be improvements in testing and research methods, as well as increased awareness. ASD is diagnosed through a series of observational tests of a person’s behavior. The tests used to diagnose ASD are prescribed by the American Psychiatric Association’s Diagnostic and Statistical Manual, Fifth Edition (DSM-5). The bulk of the testing focuses on the individual’s deficits in social communication and repetitive patterns of behavior.
The criteria used to diagnose ASD, and consequently the rate of diagnosis, has changed significantly over the years. In 1966, using the criteria at the time, it was estimated that 1 in 2500 children had ASD. Testing became standardized in the 1980s, and in 1987 the prevalence of ASD was approximately 1 in 1400 children. As testing became better, and definitions of ASD were broadened, the rates of diagnosis rose to the current rates.
Improved access to testing also seems to contribute to the increase in prevalence of ASD. Among the groups studied, white children have consistently been diagnosed with ASD at higher rates than African-American or Hispanic children. Over the years, however, the gaps among the groups of children have shrunk considerably. This becomes even more apparent when looking at different states. For example, a state like New Jersey that has better access to diagnostic services has a relatively high prevalence of ASD, but the difference between ethnic groups is virtually nonexistent. This suggests that access to testing leads to a higher rate of diagnoses for all groups.
In addition to better testing, awareness of ASD among parents and educators has risen. Better recognition of the behaviors that characterize ASD appears to be linked to higher rates of diagnosis. Parents who are better able to recognize potential signs of ASD are more likely to seek a diagnosis for their child. Furthermore, teachers and school employees are well trained to spot behaviors associated with ASD, including lack of eye contact and poor socialization. An added benefit of better recognition of ASD is an improvement of services provided to students.
ASD is, and undoubtedly will remain, an area of research that is followed closely. As can be seen, it is important to improve access to testing in order to ensure that individuals are properly diagnosed and receive quality treatments and services. Improved testing will naturally lead to better awareness among medical and educational professionals, as well as the general public. As access to testing and awareness increase, it seems possible that the prevalence of diagnosed ASD will continue to increase, too.