The proposed changes would also create a new category, "social communication disorder," which would cover those who don't exactly fit symptoms of autism, but still have trouble communicating and interacting with others.
Some experts believe up to 40 percent of those currently considered autistic will be affected and might lose their diagnoses, which could affect insurance coverage and other services, according to The Associated Press.
Diehl said many of those diagnosed with specific types of autism would lose specialized services and environments they depend on.
"A lot of people embraced the Asperger's diagnosis culture," Diehl said. "They came out of it as bigger than the diagnosis itself. Autism carries a little more of a stigma with it -- Asperger's is a less stigmatizing diagnosis."
Another potential problem with the proposed changes is the damage they could do to the reputation of the psychology field as a whole, according to Diehl.
"In some ways, there is a danger to undermining the psychology profession," he said. "A lot of families have been struggling for years to find a diagnosis."
Understandably, the definitions needed to be upgraded, according to Diehl.
"The idea is that we created the autism spectrum, and we have a catch-all category (PDD-NOS) that wasn't exactly autism," he said. "Too many people were put in there -- it sort of became autism.
"The definition is too vague. The purpose of these updates is to give more defined ideas, make them more easy to use."
These changes arrive as information released from the U.S. government reveals more children than ever -- one in 88 -- are being diagnosed with autism.
Diehl said he would like to talk to parents of children with autism.
"These are good changes," he said. "But we just need to talk about it, and to get a discussion started. The scary thing is that people don't know if they will be affected. I do think there will be some people affected."
Pierce said the changes maker her nervous.
"If insurance decides not to cover (Wesley's care), we would have trouble," she said.
When Wesley struggled with full inclusion in regular classes in public school, Pierce said, she began looking for other options.
He is now educated at the Elkhart office of Behavioral Analysis Center for Autism, which uses Applied Behavior Analysis techniques to teach autistic children how to learn.
BACA Director Nancy Warren said BACA will still provide the same treatment, no matter what a patient's diagnosis or how it changes.
"We base our research on many different types of people," she said. "For us, the label doesn't really matter."
Warren said, despite treatment not changing, it might cause more trouble for parents if a change in diagnosis affects insurance.
"Changing someone's diagnosis label doesn't change their need for service," she said. "This adds a new dimension of challenge for families and society who want to provide services."
The fact that her son has seen success in the program makes the proposed changes that much more scary, Pierce said. Insurance currently pays for all of Wesley's education. If his diagnosis were to change and no longer be labeled "autism," she said she is concerned he might not have this service covered.
"If insurance decides not to cover it, I have always wondered what would happen," she said. "It's a huge concern -- parents cannot afford to cover this out of pocket."
Indiana does have a state mandate that requires insurance companies to cover autism care, according to Pierce.
But different types of insurance have different levels of requirement. If insurance is labeled "fully funded" insurance, or comes from a health plan provided through a group policy, then the coverage is full, according to the Indiana University-based Indiana Resource Center for Autism. But if a company is "self-insured," that is, thecompany essentially acts as the insurer and provides coverage for employees, sometimes mediated by an actual insurance company, the company is not required to cover anything.
Pierce said she was once in an autism group in which only one family out of the 10 in attendance had fully funded insurance.
"So most aren't covered," she said. "There are some families that can't get their children services."
Cathy Pratt, the Indiana Resource Center for Autism's director, said state officials and agencies will continue to work hard to educate parents and families.
"IRCA will be very active in assisting people when the definitions come out," she said.
Pratt said professionals can't really know what the definitions will say until they arrive, which may not be until 2013.
"Right now, people are guessing what the impact will be," she said. "In Indiana, people are thinking that those who are at the upper end of the spectrum will lose services. However, there's the other reality where those people at the upper end have never really received services."
Even with all of the uncertainty in the future, Pierce said, she turns to her son's happiness to find a bit of peace.
"My son is very joyful," she said. "He's a very happy kid. He enjoys the little things in life, like sitting outside watching the trees. He's made me appreciate how beautiful the world is. He's really helped me enjoy the moment more."