Cindy Waeltermann's youngest son, Alex, had a strange way of playing with his toy car.

Instead of rolling it along the floor like most 18-month-olds, she said, "He held it up at eye level and spun the wheels."

That was when Waeltermann, of Wexford, suspected her son had autism. She knew the symptoms.

Many parents are receiving a similar diagnosis for their children. According to Autism Speaks, a New York-based organization that raises money for autism research, one in 150 children in the United States is diagnosed with autism, and one out of 94 boys has the disorder.

Outward symptoms of autism include distant behavior, trouble communicating, repetitive motions and physically lashing out at others, which also can cause injury to themselves.

"We think of it as a disorder of the connections in the brain," said Dr. Nancy Minshew, director of the Center for Excellence in Autism Research at the University of Pittsburgh. She has been researching the disorder for 30 years.

The brain is composed of billions of cells called neurons. Each neuron releases a chemical that crosses synapses, or gaps, in the brain to send a message. In an autistic brain, the connection is not always made.

Dr. John Carosso is a child psychologist at the Community Psychiatric Centers, which has 11 offices in southwestern Pennsylvania, including the South Hills, Monroeville and Pittsburgh. In the brain of an autistic child, Carosso said, "different parts of the brain are lighting up."

The frontal cortex, which controls higher-level functions, is more active in a non-autistic brain. But for an autistic person, the posterior cortex, which processes smaller details, is the most active.

"Various parts of the brain are working, but they're not connected well," Carosso explained. In other words, those with autism can pick up on details but cannot connect them.

In 1943, Leo Kanner, a child psychiatrist, was one of the first to coin the term "autism." Kanner saw certain common traits in children with the disorder: impairments in social interaction, good memory, extreme sensitivity to certain stimuli and limitations in spontaneous behavior and intellectual potential.

Medical professionals now can determine if a person has autism using various screening methods, such as the Diagnostic and Statistical Manual of Mental Disorders.

Researchers have classified five types of autism.

Autistic Disorder is often reflected with difficulties in social interaction and communication. Children with Asperger's Syndrome are able to communicate and tend to do well in intelligence tests but also have problems interacting with others.

Rett's Disorder has only been found in girls and is marked by dramatically slow head growth, along with repetitive hand motions, such as clapping and wringing. Those with Rett's seem to develop normally, then slowly lose communication and social skills.

This also is common with those who have Childhood Disintegrative Disorder. Here, children lose those skills between ages 2 and 4.

Pervasive Developmental Disorder-Not Otherwise Specified, or PDD-NOS, also is called atypical autism, and is a general category for those who don't fall into other categories.

Rebecca Williams-Thomas is the mother of Lee, 3, who has PDD-NOS. She recalls that he started out developing normally.

"We actually had a really good baby," Williams-Thomas, of Glen-shaw, said. "Right before his first birthday, we even took him on a nine-day cruise, and it went so smooth. Up until this time, things with Lee seemed pretty much OK."

She was stunned to watch as Lee developed behavior problems and a loss of communicative skills. At 27 months, he was diagnosed. At that point, Williams-Thomas said, she knew so little about the disorder that she couldn't even explain it to her mother.

"I spent days, weeks at first, trying to get caught up in the world of autism just so I could understand," she said.

One of the more crippling side effects of autism, Minshew said, is social awkwardness.

"That's no small deal," she said. "Our society is very demanding for social skills." She added that autistic children often are bullied because of those limitations.

Both Williams-Thomas and Waeltermann find children lacking those skills often are misunderstood.

For example, when her sons have tantrums in public places, Waeltermann says, "People don't understand why. You get looks like you're the worst person in the world."

When her children were diagnosed, Waeltermann started Autism Link and the Autism Center of Pittsburgh because she found there were few services and information available.

Williams-Thomas wants people to understand that there is no typical autistic child.

"I wish people understood that children with autism are capable of love, understanding and empathy. I wish other people knew that children with autism really are just like every other kid. They want to have friends, they want to be invited to birthday parties and belong."

Next week: Part two of the series will address how autism research has evolved and where it's going.