Ryan Massey, 11, plays with some action figures in his bedroom in Dacula, Ga. Ryan is the youngest of three brothers in his family, all of whom have Asperger's syndrome, which is a milder variant of autistic disorder.

ATLANTA — A few decades ago, people probably would have said kids like Ryan Massey and Eddie Scheuplein were just odd. Or difficult.

Both boys are bright. But Ryan, 11, is hyper and prone to angry outbursts, sometimes trying to strangle another kid in his class who annoys him. Eddie, 7, has a strange habit of sticking his shirt in his mouth and sucking on it.

Both were diagnosed with a form of autism. And it's partly because of children like them that autism appears to be skyrocketing: In the latest estimate, as many as one in 150 children have some form of this disorder. Groups advocating more research money call autism "the fastest-growing developmental disability in the United States."

Indeed, doctors are concerned there are even more cases out there, unrecognized: The American Academy of Pediatrics last week stressed the importance of screening every kid — twice — for autism by age 2.

But many experts believe these unsociable behaviors were just about as common 30 or 40 years ago. The recent explosion of cases appears to be mostly caused by a surge in special education services for autistic children, and by a corresponding shift in what doctors call autism.

Autism has always been diagnosed by making judgments about a child's behavior; there are no blood or biologic tests. For decades, the diagnosis was given only to kids with severe language and social impairments and unusual, repetitious behaviors.

Many children with severe autism hit themselves or others, don't speak and don't make eye contact.

In the 1990s, the autism umbrella expanded, and autism is now shorthand for a group of milder, related conditions, known as "autism spectrum disorders."

The spectrum includes Asperger's syndrome and something called PDD-NOS (for Pervasive Developmental Disorder-Not Otherwise Specified). Some support groups report more than half of their families fall into these categories, but there is no commonly accepted scientific breakdown.

Gradually, there have been changes in parents' own perception of autism, the autism services schools provide, and the care that insurers pay for, experts say.Eddie, of Buford, Ga., was initially diagnosed with obsessive-compulsive disorder, attention deficit hyperactivity disorder and other conditions. But the services he got in school were not very helpful.His mother, Michelle, said a diagnosis of autism brought occupational therapy and other, better services."I do have to admit I almost like the idea of having the autistic label, at least over the other labels, because there's more help out there for you," said Scheuplein.Whether it's because of genes or the environment, autism has hit the Massey family hard. Chuck and Julia Massey, of Dacula, Ga., have three sons with Asperger's.The youngest, Ryan, was first diagnosed after he was slow to develop speaking ability. His brothers — Trevor, 14, and Morgan, 16 — had learning and behavior problems and were later diagnosed with Asperger's, too.All got special education services and were treated with medications. Morgan has improved, or matured, or both, and is now a social kid in mainstream classes at a Gwinnett County high school. Trevor seems to be making the same transition, his mother said.Ryan is the most extreme. He still has uncontrollable tantrums and must attend an Asperger's-only sixth-grade classroom that teaches social skills along with traditional subjects.In a recent interview at the family's home, Ryan acknowledged he still has anger control issues. One of the three other students in his class is particularly irritating. Ryan said the way he reacts is by "grabbing his throat."Ryan acknowledged it's been educational living in a house full of Asperger's kids. Asked to name something he's learned from his brothers, he replied, "Swears."