Prevalence Rate of Autism Continues Steady Rise

On March 28, the Centers for Disease Control and Prevention (CDC) published in its Morbidity and Mortality Weekly Report that 1 in 68 American children has autism spectrum disorder (ASD). That translates to 14.7 per 1,000 8-year-olds.

This rate is about 30 percent higher than the prevalence of ASD that the CDC reported in 2012, which was 1 in 88 children—that is, 11.3 per 1,000 8-year-olds.

The new finding is based on 2010 data from 11 sites participating in the CDC’s long-running Autism and Developmental Disabilities Monitoring (ADDM) network. A total of 363,749 8-year-old children were evaluated for the report, representing 9 percent of the U.S. population of 8-year-olds in 2010. (The 2012 report reflected data gathered in 2008.)

Other new findings indicate that ASD is almost five times more common among boys than girls and that white children are more likely to be identified with the disorder than black or Hispanic children are. Although the level of intellectual ability varies greatly among children with ASD, ranging from severe intellectual challenges to average or above-average intellectual ability, the new findings likewise show that almost half the children identified with ASD have average or above-average intellectual ability.

“The CDC report was based on a review of records rather than actual clinical assessments,” David Fassler, M.D., a clinical professor of psychiatry at the University of Vermont, a child and adolescent psychiatrist, and APA treasurer, noted in an interview with Psychiatric News. “As a result, it tells us more about how often autism is being diagnosed as opposed to changes in the underlying incidence. The data were also derived from relatively few states. However, even in this limited sample, the geographic variations are quite striking and clearly warrant further investigation. From a clinical perspective, increased awareness is leading to earlier recognition and more accurate diagnoses. The real challenge is to make sure that all these kids have access to the comprehensive services they need and deserve.”

“Is this increase [in ASD] a mark of better care, with more cases identified and treated, or is this a reflection of a continually growing public health care emergency due to more children affected?” Thomas Insel, M.D., director of the National Institute of Mental Health, asked in his March 27 blog. “ADDM cannot answer these questions, but it does point to the need for a population-wide study, as currently planned by

the CDC and Autism Speaks in South Carolina…. Whatever the meaning of the new ADDM report, there is little doubt that more children and more adults on the autism spectrum will require more services.”

Ever since the ADDM was launched in 2000, ADDM staff members have determined cases of ASD in two phases. The first phase involves screening and abstracting records from multiple sources in the community. In the second phase, clinicians review the collected data and determine whether putative ASD cases are truly ASD according to DSM criteria. ASD case definitions for both 2010 and 2012, as well as for the earlier years, were based on DSM-IV-TR. However, beginning this year, ASD case definitions will be based on DSM-5 criteria.

Since its first study of autism prevalence, the ADDM has found that the number of children diagnosed with the disorder has been on a steady upward trajectory. Indeed, “The global prevalence of autism has increased 20-fold to 30-fold since the earliest epidemiologic studies were conducted in the late 1960s and early 1970s,” the new report noted. ■

“Prevalence of Autism Spectrum Disorder Among Children Aged Eight Years—Autism and Developmental Disabilities Monitoring Network, 11 Sites, United States, 2010” can be accessed here.