As a chubby, smiling baby boy, Marlon Barton delighted everyone around him. Now that he is a strapping young man who flaps his hands and makes odd noises, no one knows quite what to do with him.

Barton is 26 years old, 6 feet 2, 283 pounds and acutely autistic. He was diagnosed when the condition was considered unusual and when doctors offered little hope to parents of the children who suffered from it.

His mother, Pearlie Barton, cares for her son around-the-clock now in their south Sacramento home. "He scares people, even though he usually is not aggressive," she said.

"Being large, African American and autistic does not work in his favor," either socially or in programs designed to help people with disabilities, she said.

Autism, a neurodevelopmental disorder that affects language and social skills, was relatively rare when Barton was born. Since then, for reasons that are unclear, diagnoses have skyrocketed and the condition is surfacing in an estimated 1 in 150 children.

As a tidal wave of these youngsters moves toward adulthood with complex behavioral and medical problems, society is largely unprepared.

"We don't have the programs. We don't have the research," said Dr. Robert Hendren, director of the UC Davis M.I.N.D. Institute. "We have this very large adult population of autistics coming along, and we don't know how to deal with them. We just haven't come to terms with it."

But the futures of hundreds of thousands of autistic people in America cannot be ignored for long, said Hendren and others.

In California, regional centers will be serving more than 50,000 autistic people of all ages by the end of this year, according to the state Department of Developmental Services. If the trend continues, that number will grow to 70,000 by June 2012.

By 2013, according to the department, more than 4,000 teenagers with autism will reach adulthood, and by 2018 the agency will be serving more than 19,000 adults with the condition. Nationally, the number of autistic children expected to need extensive adult services by 2023 is about 380,000 people, and the bill for caring for them will be in the billions of dollars.

Care providers are just beginning to grapple with how to deal with the surge, even as governments slash social services to cope with budget deficits.

"The financial impact will be huge," said Hendren. "Many, many people will be living impaired lives, and where are they going to go? Who will take care of them? The challenge will fall largely to family members. As those parents age, they are asking, 'Who is going to take care of my autistic child after I am gone?' "

It is a question that haunts Pearlie Barton, 58, and her friend Helen Richard, 78, who also has an adult autistic son.

"Right now, every time I leave Marlon out of my sight I'm taking a chance," said Barton, recalling how once, when she looked away for a moment, her son wandered into a women's restroom. "I have to watch him every minute. But I'm not going to be around forever."

Research focuses on children

Some people with autism, including Ray Richard, can speak and care for themselves with limited supervision. Some are able to work, if employers are willing to adapt to their limited social skills. Others, like Marlon Barton, are entirely dependent on caretakers and family members. Day programs, job opportunities and housing options geared specifically toward adults with autism are limited.

"There's really nothing out there to meet the needs of these guys, even guys who are as highly functional as Ray," Richard said. Her son is 43 years old and has Asperger's syndrome, a milder form of autism.

"Ray can type 40 words per minute," Richard said. "He has a great vocabulary. He has a photographic memory, but I can't get him a job because you can't really teach socialization. It's terrible."

Life for her son might have been better, she said, had he had access to training programs when he was younger.

Hundreds of millions of dollars a year are now devoted to research around autism. But the vast majority of studies and treatment are focused on children, whose brains are still developing and who, with early intervention, have a good chance to develop speech, social, and vocational skills.

Call The Bee's Cynthia Hubert, (916) 321-1082.