SUNDAY, Dec. 16 (HealthDay News) -- Despite media reports alleging that the gunman involved in the Connecticut school shootings had Asperger's syndrome, experts were quick to assert Sunday that there is no link between the condition -- a mild form of autism -- and violence.

"There really is no evidence that links autism or Asperger's to violence," said Geraldine Dawson, chief science officer at the nonprofit advocacy group Autism Speaks and a professor of psychiatry at the University of North Carolina at Chapel Hill.

There has been speculation that 20-year-old Adam Lanza, the gunman who perpetrated Friday's senseless massacre at an elementary school in Newton, Conn., had Asperger's, which is considered a high-functioning form of autism.

Lanza fatally shot his mother at her home before forcing his way into Sandy Hook Elementary School and killing 20 children, aged 6 and 7, as well as six adults and then himself. It is one of the worst mass shootings in U.S. history.

A law enforcement official involved in the case, speaking on condition of anonymity, told the Associated Pressthat Lanza had been diagnosed with Asperger's syndrome.

Asperger's has its own designation in the current Diagnostic and Statistical Manual of Mental Disorders( DSM-4), considered the Bible of psychiatry, which has been in use since 1994. However, as of the spring of 2013, when the new DSM-5comes out, "autistic disorder" will be known as "autism spectrum disorder" and Asperger's will be folded within that larger category.

Certain characteristics are common across the autism spectrum, experts said.

"Two features that characterize autism spectrum disorders are difficulties in the area of social interactions and also a tendency to engage in repetitive behavior, whether this is a high-functioning person or one who's severely affected," Dawson explained. "Those are the two common features."

However, in the DSM, "there is no linking of this syndrome with violence in any way," she added.

Former classmates said Lanza was painfully shy, reserved and socially awkward, according to news reports. Those characteristics can be typical of Asperger's, experts said.

People with autism spectrum disorders, including those with Asperger's, may exhibit aggressive behavior when compared with peers, but it is a completely different type of aggression than that witnessed Friday, said Eric Butter, assistant professor of pediatrics and psychology at Ohio State University.

"Research suggests that aggression among people with autism spectrum conditions can occur 20 percent to 30 percent more often than compared to the general population," he said. "But, we are not talking about the kind of planned and intentional type of violence we have seen at Newtown.

"Aggression that we see in autism can best be described as disruptive and irritable behavior and is often consistent with the communication and social difficulties that are the hallmarks of autism spectrum disorders," he added. "It is a very human experience that when you cannot explain how you are feeling, that you will then act out in frustration, anger, and aggression. But, it is notconsistent with the diagnosis that you would plan and execute a crime like we saw here."

Aggression in people with Asperger's and autism tends to be more reactive, such as "impulsive outbursts, being quick to anger, shoving or pushing, shouting in anger, and being slow to cool off when angry," said Butter, who is also associate director of the Child Development Center at Nationwide Children's Hospital in Westerville, Ohio.

The types of violence seen in Connecticut and elsewhere "have occurred at the hands of individuals with a range of psychological profiles, and the underlying and connected theme is that we have not done enough in our schools and mental health services systems to identify, assist, and de-stigmatize those people suffering from the illnesses of the brain," Butter said.

Added Dawson: "Whenever there is a horrible tragedy like this one, people want to make sense out of it and they're trying to look for answers. I think it's important that we be very clear that if this individual did have Asperger's or autism, which we don't know [for sure] that he did, this is not going to help us understand what happened. Because there really is no link between the two."

More information

For more on autism spectrum disorders, visit Autism Speaks.