CDC Report Suggests Increase in Autism Spectrum Disorder
A new Centers for Disease Control and Prevention (CDC) summary report estimates an increase in the United States of some 30 percent in children with autism spectrum disorder (ASD), bringing the ratio as high as 1 in 68 children, compared to 2012 estimates of 1 in 88. Of the eight-year-olds identified with ASD, numbers ranged from 1 in 175 in Alabama to 1 in 45 in New Jersey. In compiling the report, researchers used community records for children with developmental disabilities, taking care to maintain the same data collection methods and diagnostic criteria used for the 2012 report.
Although the numbers have increased significantly, some characteristics of ASD have remained the same. Boys continue to be identified at rates five times higher than girls, and ASD is more likely to occur among white children than black or Hispanic. The study also found increased rates of above-average intellectual ability among children with ASD compared to 10 years ago. A key finding is that most children with ASD are not diagnosed until after age four, even though an accurate diagnosis can be made as early as two years of age. This is a particularly important finding with major public health consequences, given the importance of early diagnosis in predicting more effective outcomes for these children.
To support the objective of early diagnosis, the CDC promotes developmental and behavioral screening through the Learn the Signs, Act Early program. The newly launched Birth to 5: Watch Me Thrive campaign will aid families to identify potential developmental delays as early as possible, and will improve available educational supports. The objective of this “act early” message to parents, health professionals and educators is to increase the number of young children with ASD who are screened and evaluated, allowing them to be enrolled in early intervention services as soon as possible.
There are a number of ways to learn the signs and act early enough to make a significant difference in the future lives of children with autism. The CDC provides developmental milestone materials to help measure progress in children’s mobility, speech, learning and behavior. A number of standardized and validated developmental screening tools are also available and effective in assessing and monitoring progress. Genetic testing is another important early identification method. Studies have documented changes in the chromosomal structure of children with autism spectrum disorders and have discovered autism “hot spots” in their DNA. One such test called the chromosomal microarray (CMA) can scan for these duplications and deletions across all of a patient’s chromosomes and should be appropriately used for patients when a clinical history and examination do not point to a specific genetic or non-genetic cause of globaldevelopmental delay or ASD. Various guideline bodies including the American College of Medical Genetics1,2,3, American Academy of Pediatrics4, and American Academy of Neurology5 have recommended the CMA as a first line test for diagnosing such patients. More advanced testing including analysis of mutations or deletions in the SHANK2 and SHANK3 genes can also be used to diagnose ASD or other associated syndromes. These genes play a role in abnormal neuron synaptic function and predispose to ASD or intellectual disability.
Given the increase in rates of autism and the fact that early intervention is the single most powerful way to improve developmental outcomes for children with autism, it is essential that diagnosis is done as early as possible. The Affordable Care Act will help American parents access many preventive services for children, even as young as 18 months. While it is never too late to get help for a child diagnosed with autism, the earlier the better. It is therefore incumbent upon both parents and health professionals to remain aware of the signs and to take advantage of all available diagnostic tools to help ensure that children with ASD are given every opportunity to succeed and thrive.
1. Kearney HM, South ST, Wolff DJ, et al. American College of Medical Genetics recommendations for the design and performance expectations for clinical genomic copy number microarrays intended for use in the postnatal setting for detection of constitutional abnormalities. Genet Med. 2011;13:676-679.
2. Manning M, Hudgins L, Professional Practice and Guidelines Committee. Array-based technology and recommendations for utilization in medical genetics practice for detection of chromosomal abnormalities. Genet Med. 2010;12:742-745.
3. Miller DT, Adam MP, Aradhya S, et al. Consensus statement: chromosomal microarray is a first-tier clinical diagnostic test for individuals with developmental disabilities or congenital anomalies. Am J Hum Genet. 2010;86:749-764.
4. American Academy of Pediatrics. Statement of Endorsement: Genetic and metabolic testing on children with global developmental delay. Pediatrics. 2012;129:e825. doi:10.1542/peds.2011-3485.
5. Michelson DJ, Shevell MI, Sherr EH, et al. Evidence report: Genetic and metabolic testing on children with global developmental delay: report of the Quality Standards Subcommittee of the American Academy of Neurology and the Practice Committee of the Child Neurology Society. Neurology. 2011;77:1629-1635.