Skip to content
My WebMD Sign In, Sign Up

Autism Cases on the Rise; Reason for Increase a Mystery

Scientists are scouring genetic and evironmental data to find a cause for the rise in autism.
By
WebMD Feature
Reviewed by Louise Chang, MD

The number of children diagnosed with autism or related disorders has grown at what many call an alarming rate. In the 1970s and 1980s, about one out of every 2,000 children had autism.

Today, the CDC estimates that one in 150 8-year-olds in the U.S. has an autism spectrum disorder, or ASD. This expanded definition refers not only to autism but also to a collection of brain development disorders such as Asperger's syndrome and a condition known as pervasive developmental disorder -- not otherwise specified (PDD-NOS). Though all the disorders share some symptoms, they are different in other ways, including the timeline of symptoms and the severity, according to the CDC.

Recommended Related to Autism

Autism and Family Relationships

Alison Singer's days became a blur eight years ago when her daughter Jodie, now nearly 11, was diagnosed with autism. Singer left the workforce temporarily and focused on her daughter. "I set up the home program -- 40 hours a week of applied behavioral analysis therapy," says Singer, referring to a common autism treatment. There were appointments for evaluations to schedule -- and then get to -- and numerous decisions to make. "Your life becomes dominated by autism," Singer remembers. "I used...

Read the Autism and Family Relationships article > >

The apparent rise in cases triggers two burning questions for parents, physicians, and scientists:

  • Is autism truly on the rise, or do the new statistics simply reflect the growing awareness of the condition, the expanded definition, and other factors?
  • If autism is on the rise, as most experts believe, what is causing the increase?

(Does someone you love have autism? Join other parents and caregivers on WebMD's Autism Support Group message board.)

Autism: A True Increase or Semantics?

The jump in autism cases has spawned not only alarm but also debate about whether the number of children with autism could have increased that much in a relatively brief time.

"There's a lot of controversy about that," says Jeff Milunsky, MD, director of clinical genetics and associate director of the Center for Human Genetics at Boston University.

Two researchers who tracked the rate of autism in children born in the same area of England from 1992 to 1995 and then from 1996 to 1998 found that the rates were comparable, and concluded that the incidence of autism was stable. The study was published in the American Journal of Psychiatry in 2005.

But, Milunsky  says, several studies have documented an increase in the U.S.

In a recent report in the journal Archives of Disease in Childhood, Milunsky and his colleagues point to several studies finding an increase in autism rates. In 2003, for instance, a large study conducted in Atlanta found that one in 166 to one in 250 children had autism, according to a report published in the Journal of the American Medical Association.

Another study conducted by the CDC in 14 states found an overall prevalence of one in 152, which Milunsky and others say is the generally accepted figure today.

Other experts say autism is on the increase but that factors other than more children being diagnosed play a role. Some of the increase in reported cases is because of "diagnostic substitution," says Paul Shattuck, PhD, assistant professor of social work at Washington University in St. Louis and an autism researcher.

"A kid labeled autistic today could have been labeled mentally retarded 10 years ago in the same school system," Shattuck says. It wasn't until 1992 that schools began to include autism as a special education classification.

Next Article:

Would the fear of autism keep you from getting your child vaccinated?