Why Is It on the Rise?
Researchers aren't just looking into exactly what causes autism -- they're also probing reasons for its recent skyrocketing incidence. Autism is so perplexing and mysterious that experts are beginning to worry that something in the environment may be causing it -- but so far, there's no evidence to support that, says Dr. Sandler.
In fact, many experts say that the rise may not be due to more kids being afflicted with autism, but rather more cases being diagnosed. Today, experts talk not just about autism, but about autism spectrum disorder, which encompasses a greater range of symptoms. It's possible that many of today's kids with autism used to be called something else, such as learning disabled or mentally retarded, says Dr. Powers. Other kids might have been labeled eccentric or unusual -- but not disabled.
For example, kids with Asperger syndrome, sometimes called high-functioning autism, fall under autism spectrum disorder, even though Asperger syndrome tends to be more subtle. A child with Asperger's isn't necessarily antisocial, but he may have difficulty having conversations or reading social cues. However, his language is normal and he may even be precocious, says Dr. Powers. Asperger's is typically diagnosed around age 6 or older. Before that, a child doesn't usually develop the intense interest in a certain subject, like trains or math -- that's the hallmark of Asperger syndrome.
Other children might be diagnosed as PDD-NOS, which stands for pervasive developmental disorder, not otherwise specified. This residual category holds a large group of kids who have maybe two out of the three classic social, language, and behavioral characteristics of autism, says Fred Volkmar, MD. There are many more of these children than those who are diagnosed as classically autistic, but they're all lumped together.