The rate of children on the autism spectrum in Maryland jumped to one in 50 in the latest report released Thursday by the Centers for Disease Control and Prevention on the disorder's prevalence. It was one in 55 two years ago.
Nationwide, the CDC reported the rate increased to one in 59 children from one in 68 two years ago. That's the highest prevalence since the health agency began tracking the disorder 18 years ago.
The increases were not necessarily a surprise to public health officials, who said they don't know if there are actually more cases, or if awareness and diagnosis have improved. Still, the numbers are important for giving an idea of the disorder's reach, said Rebecca Harrington, who helped lead the data gathering in Maryland through the Johns Hopkins Bloomberg School of Public Health.
"There remains a lot of children in Maryland who have autism spectrum disorder, and they and their families are going to need more services," Harrington said.
Boys were four times more likely to be identified with autism spectrum disorder than girls. The rate is one in 38 among boys and one in 152 among girls around the country. In Maryland, the rate was one in 31 boys and one in 139 girls.
It is uncertain why the rates in boys are higher, Harrington said. One reason might be that girls present differently, so they might be undercounted.
The information released Thursday was based on data of children who were age 8 in 2014. In Maryland, data was collected from the health and special education records of children living in Baltimore County by researchers from the Johns Hopkins Bloomberg School of Public Health.
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Autism spectrum disorder is a developmental disorder that causes social and communication difficulties, limited interests and repetitive behaviors. Early diagnosis and intervention can help improve learning and skills. The causes of autism are not completely understood. Studies show that both environment and genetics may play a role.
The rates have been rising since the 1960s, but researchers do not know how much of this rise is due to better screening, diagnostic services and treatment and intervention. The medical community also has improved the way it documents the disease and is better at identifying autism-related behaviors.
Maryland's numbers also may be higher because of better documenting of the disorder through places like the Kennedy Krieger Institute, known for its research and treatment of autism.
The CDC collected data at 11 regional monitoring sites that are part of the Autism and Developmental Disabilities Monitoring Network, including Maryland.
Prevalence of U.S. rates of the disorder in past years were:
- one in 68 children in the 2016 report that looked at 2012 data;
- one in 68 children in the 2014 report that looked at 2010 data;
- one in 88 children in the 2012 report that looked at 2008 data;
- one in 110 children in the 2009 report that looked at 2006 data;
- one in 150 children in the 2007 report that looked at data from 2000 and 2002.