DETROIT — If you want Jenny McCarthy to accomplish something, tell her she can't.

People told her she'd never make it in Hollywood. They told her she didn't have the stuff to become a successful actress, comic or author.

Yet the former Playboy model did all that. And she believes it was all a setup for her greatest challenge: using her celebrity to become an almost one-woman crusade for autism awareness, advocacy and prevention.

Along with another Hollywood celebrity — her man friend Jim Carrey — she's planning a march in Washington on June 4 aimed at drawing national attention to autism awareness and prevention.

In conversation and in her book "Louder Than Words: A Mother's Journey in Healing Autism" (Dutton), she offers plenty of reasons why autism ought to be at the top of the nation's agenda.

Approximately one in 150 American children is autistic.

That's up from an estimated five in 10,000 children in the late 1980s, according to her book and a variety of sources.

Most doctors and researchers attribute the dramatic rise to better methods of diagnosing the disorder.

But McCarthy and others say there's a correlation between childhood immunizations and the rising rates of autism.

Numerous studies have addressed vaccines and autism and found no link, including with a once-common mercury-based preservative.

Autism is a developmental disorder that affects children in widely varying ways. But children with autism often have difficulty communicating, playing with other children and toys, and expressing or receiving affection. Some have seizures, tantrums and a variety of allergies.

Although the growing number of autistic children concerns McCarthy, autism matters to her because of one little boy: her son, Evan, now 5 years old and no longer considered autistic.

He was diagnosed when he was 2 years old.

"People told me, 'You'll never heal your kid; he'll never talk,' " McCarthy said from her Los Angeles home. "They told me I'd never hear him say, 'Mama, I love you.' "

ATTRIBUTES CURE TO DIET

McCarthy believes she was successful because she put her son on a wheat-free, dairy-free diet, supplemented by vitamins and minerals, that she believes cleansed his body of an overgrowth of yeast.

Doing so cleared Evan's mind and body so he could be more receptive to other therapies he was receiving in hospitals and privately, including play and behavior therapy, McCarthy said.

She said her first piece of reassuring evidence that her approach was working came about five months after Evan began the regimen. McCarthy and Evan were in bed together watching "SpongeBob" on television.

"Instead of just watching the colors flashing on the screen, he understood the joke and laughed," she said.

McCarthy said the regimen may not work for every child, but in the months since her book was released in September, she has heard from hundreds of mothers who believe their children have benefited.

Although positive results are possible, especially with early intervention, it's unknown how often they occur or to what degree, because autism encompasses a broad spectrum of symptoms and severity, said Marguerite Kirst Colston, a spokeswoman for the Autism Society of America, an information and support network.

"It really depends on what you mean by healing," she said. "But with the right support, you can lose the diagnosis."

"We don't have the numbers because it hasn't been tracked properly, but at the Autism Society of America, we are hearing more and more anecdotal cases where parents are saying their child is healed. The numbers are small, but growing."

BAD/GOOD DOCTORS

McCarthy said it's to her advantage that she has never cared what others think or say about her. And she can be harsh in the face of resistance to getting help for her son.

"I was only harsh when met with ignorance," she said. "When doctors tell you that trying to feed better food to your child is bad medicine, you better be darn sure I'm going to be harsh."

Although she met several good doctors, she said, she met too many who were rude and condescending and closed-minded.

"I believe doctors need to practice a new behavior called respect," she said.

McCarthy said she is not opposed to immunizations; she simply believes there are too many too soon. She asked why the number of vaccinations recommended by the Centers for Disease Control increased from 10 in 1983 to 36 now.

She recommends looking into alternatives to the standard schedule of shots and studying precautions as outlined on the Web site www.generationrescue.org. It's run by an organization of parents focused on treating and curing autism and other disorders.

Dr. Ahdi Amer, a member of the Michigan Advisory Committee on Immunizations and a pediatrician at Children's Hospital of Michigan, said the number of vaccines has gone up because there is more knowledge about which immunizations can safely protect children from diseases.

He called it dangerous to advise parents to do anything other than what is recommended by the Centers for Disease Control, which bases its recommendation on well-documented studies.

"This is the reason in this country we do not have the higher mortality rates that you see in some countries," he said. "There is no scientific link or proof between autism and immunizations."

Amer said the rising rate of autism is the result of better methods for diagnosing the disorder. He thinks some parents believe there's a link to vaccines, especially to the MMR vaccine (measles, mumps and rubella), because the MMR is given at 15 months. It is generally after that age than autism manifests itself.

However, autism occurs at the same rate in children who don't get the shot at that age, Amer said.

"We are kind of in a race to get these babies vaccinated as soon as they can be to fight against diseases that used to kill them in the past," he said.

HELP FOR PARENTS

Autistic children typically show signs of the disorder within the first three years of life. Signs to look for include: