Amid reports from neighbors and classmates that the gunman in the shooting rampage in Newtown, Conn., had an autism variant known as Asperger's syndrome, adults with the condition and parents of children with the diagnosis are fighting what they fear may be a growing impression that it is associated with premeditated violence.
Individuals with autism spectrum disorders, who are often bullied, frequently do suffer from depression, anxiety and suicidal thoughts. A divorce mediator who met with the parents of Adam Lanza, the gunman, during their divorce told the Associated Press that the couple had said that their son's condition had been diagnosed as Asperger's syndrome.
But experts say there is no evidence that they are more likely than any other group to commit violent crimes.
"Aggression in autism spectrum disorders is almost never directed to people outside the family or immediate caregivers, is almost never planned, and almost never involves weapons," said Dr. Catherine Lord, director of the Center for Autism and the Developing Brain at NewYork-Presbyterian hospital.
Lord said that in an unpublished review of data tracking several hundred adults with autism over at least the past five years, she and fellow researchers found no use of weapons. Among more than 1,000 older children and adolescents in that study, only 2 percent were reported by parents to have used an implement aggressively toward a nonfamily member -- fewer than in a control group.
But some Twitter messages, electronic postings and media reports in the aftermath of the massacre have not reflected that characterization of autism.
"Try curing the real disease, Autism, not the N.R.A.," one individual on Twitter wrote in response to calls for tighter gun control laws.
On the DailyKos, a blogger who identified himself as having Asperger's syndrome worried that the actions of Lanza, who killed 20 young children and seven adults, including his mother, and was described by a classmate as having a "very flat affect," might be how "people with this disability are defined in the popular imagination."
His own flat affect, he said, does not mean that he has no feelings. "Our emotions don't naturally show on our faces ... people think you're not feeling when you may be feeling even more strongly than they are."
The roots of autism, a developmental condition characterized by social impairment, communication difficulty and repetitive patterns of behavior, are not well understood. But it is a problem in processing social information, not an intrinsic inability to empathize, that underlies the condition, experts said.
"The media's continued mention of a possible diagnosis of Asperger syndrome implies a connection between that and the heinous crime committed by the shooter," said Lori S. Shery, president of the Asperger Syndrome Education Network, an advocacy group in New Jersey.
"They may have just as well said, 'Adam Lanza, age 20, was reported to have had brown hair.'"