CHICAGO (AP) - The American Academy of Pediatrics has issued its first guidelines on autism amid reports that its prevalence may be increasing. The academy hopes to dispel myths that the disorder is caused by a vaccine and that miracle cures have been discovered.

The new policy statement stresses that early diagnosis is critical for effective treatment. Suspected cases should be promptly referred to specialists, the guidelines say.

Conservative estimates suggest that 1 in 1,000 children has autism and that at least twice as many have related disorders. Research from the 1960s suggested it was about half as prevalent back then.

The apparent increase may reflect a true rise in prevalence, changes in diagnosis criteria to include milder versions of autism, and better recognition by parents and doctors, the academy said in the May issue of its journal, Pediatrics.

The guidelines are an attempt to help pediatricians become more familiar with the brain disorder, said Dr. Adrian Sandler, a pediatrician from Asheville, N.C., who heads the committee that wrote the guidelines.

Psychologist David Holmes, an adviser to the Autism Society of America, called the new guidelines an important step. Autism has been recognized as a syndrome since 1943 but has been underdiagnosed ``because the primary gatekeepers of our health system are not up to date,'' he said.

While there is no cure, ``the sooner we see these kids as professionals, the better the prognosis,'' Holmes said.

Substantial progress has been made in the past 20 years in developing drugs and behavioral and educational programs that can influence brain development and result in significant improvement.

Autism is much more common in boys and typically shows up by age 3. Affected children may not respond when talked to, fail to make eye contact and engage in repetitive behavior such as rocking and head-banging. They often have a severely limited range of interests and may be unusually sensitive to sounds or touch.

Experts think there are many causes but believe genes play a role.

Recent British research suggested that the measles-mumps-rubella vaccine might be a cause, a theory ``that has not been substantiated by more in-depth research,'' according to the academy. Doctors should reassure parents about vaccine safety and encourage parents to immunize their children, the guidelines say.

Numerous unconventional treatments also have emerged, including the highly publicized digestive enzyme secretin. But a study in May's Pediatrics involving 64 autistic children found it was no more effective than a placebo, bolstering previous research showing it had no benefits.

Pediatricians should nonetheless be knowledgeable about alternative treatments since many parents may seek them, the academy says.

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