In Tennessee, about 1 in 28 (3.6%) of 4-year-old children and about 1 in 29 (3.4%) of 8-year-old children were identified with autism spectrum disorder by the Tennessee Autism and Developmental Disabilities Monitoring Network.
Vanderbilt University Medical Center researchers, as part of the Centers for Disease Control and Prevention Autism and Developmental Disabilities Monitoring (ADDM) network, have reported an increase in the number of children in Tennessee and the U.S. with autism spectrum disorder (ASD).
The findings, published in the CDC’s Morbidity and Mortality Weekly Report series on April 15, document that over 3% of children in the state (1 in 29; 3.4%) and nation (1 in 31; 3.2%) have autism. This represents a doubling of the estimated number of children with autism in Tennessee since the research team first investigated prevalence in Tennessee a decade ago (2014: 1 in 68; 1.5%).
The team, led by Zachary Warren, PhD, executive director of the Vanderbilt Kennedy Center’s TRIAD autism institute (VKC TRIAD) and director of the Division of Developmental Medicine in the Department of Pediatrics, has been funded by grants from the CDC to conduct population studies on the prevalence of autism for both 4- and 8-year-old children in an 11-county region of Middle Tennessee. The current report examined education and medical records to estimate autism prevalence in Tennessee and combined this data with that from 15 other communities across the U.S. to estimate national prevalence, which varied substantially in the current report (from 1% in Texas to over 5% in California).
“The documented increases we’ve seen in Tennessee and the nation certainly relate to increased awareness, changes in diagnostic practices and better prevalence studies themselves,” explained Warren, who holds the Donna and Jeffrey Eskind Family Chair in Autism Spectrum Disorder. “There are also likely other complicated factors that are related to a true increase in autism, but our methodology doesn’t tell us explicitly about cause. What it does tell us is how unbelievably common ASD is in our communities. These findings powerfully push us to build effective and efficient systems of care capable of serving 3-5% of kids with autism.”
The national data also offers a deeper look into the demographics of children diagnosed with ASD. Boys are three times more likely than girls to be diagnosed with ASD, and racial/ethnic minority groups are also more likely to be identified with ASD than white children. Almost 40% of those with ASD also had an intellectual disability (IQ < 70).
The ADDM data also shows progress in the early identification of ASD in Tennessee. The 4-year-old children studied were 2.6 times as likely to receive an ASD diagnosis or ASD special education classification by 48 months of age compared to the 8-year-old children who were born in 2014.
Findings in Middle Tennessee and subsequent contributions to the CDC’s ADDM network are possible due to VKC TRIAD’s strong partnerships with the Tennessee Department of Education, Department of Health and Department of Disability and Aging.
“We’re in a tremendous position to be able to do this work due to VUMC and state partnerships,” said Alacia Stainbrook, PhD, co-director of VKC TRIAD. “This work allows us to truly understand the size and scale of the need, but we’ve also been uniquely positioned to act on this need in partnership with forward-thinking state agency leaders.”
The Tennessee Department of Education and Tennessee Early Intervention System support several VKC TRIAD capacity-building partnerships through professional development, training and technical assistance contracts.
“The shifts we’ve seen in terms of improved early identification in our state are a direct result of that funding and broader partnerships,” Stainbrook said.
The new CDC report also provides data on how children with autism were identified, noting percentages of children with autism identified with specific assessment tools. The work of Warren and VUMC colleagues in designing and disseminating a tool for telemedicine-based assessment of autism was highlighted in these findings. In some states in the ADDM network, nearly 30% of children identified at early ages were identified using TELE-ASD-PEDS — with some 14% of young children in Tennessee identified with this tool.
“VUMC is seen as an international leader in ASD tele-practice. Our partnerships with the state, in combination with grants from the National Institute of Mental Health, allowed us to be on the cutting edge of assessment tool development,” Warren said. “It is very rewarding to see that literally thousands of kids across the country are benefiting from use of that tool.”
The Tennessee ADDM network is planning to publish prevalence data again in two years and has also been funded to conduct novel studies of cerebral palsy in Tennessee.
