BY GREG LAVINE
THE SALT LAKE TRIBUNE

    When Edward Ritvo was in Salt Lake City working on his pioneering Utah autism study in the 1980s, he received a call from a woman scheduled to come in for an interview. The mother of three children with autism announced she was only willing to come as far as a nearby Arctic Circle restaurant.
    The California researcher rushed over to the fast food joint, put each child at a separate table with an order of french fries and conducted his interviews. The meeting revealed the mother was mildly autistic, though she never had been diagnosed.
    "This is the prototypic challenge we met in doing our research," Ritvo, an emeritus psychiatrist at the University of California, Las Angeles, recalled earlier this month at an autism conference in Salt Lake City. From such unusual interviews, researchers gleaned vital information about what was then a little-understood disorder.
    Today, doctors recognize autism as a developmental disorder that can affect people to various degrees. Some with autism who show few signs of the problem can go through life unaware they even have the disorder. More serious cases involve children who may show multiple signs of autism throughout their lives.
    "We're dealing with a disease that is worldwide," Ritvo said.
    Typical symptoms in children include a tendency to become disturbed by changes in routine, engage in physical over- or under-activity, show little to no eye contact and be unresponsive to verbal cues.
    Several decades of research have not yet yielded an autism cure, though laboratories are zeroing in on the disorder's causes. DNA analysis of many autism patients shows a problem in the genes that dictate timing for brain growth and development. At one point early in life, the brain may rapidly develop and then suddenly stop, Ritvo said.
    As doctors become better at spotting autism, there are still no solid figures for how many people have the disorder, said another speaker at the conference, Eric Fombonne, who studies childhood psychiatry in Montreal at McGill University and the city's children's hospital.
    Various U.S.-based studies have estimated the disorder appears in anywhere from 5 to 60 people per 100,000. Each study used different methods, making it difficult to directly compare the statistics.
    Fombonne offered a conservative estimate of 10 people per 100,000. The definition of autism has been changing constantly since it was identified in 1943, making it tough to guess whether the disorder is more or less prevalent today.
    One thing recent research has been consistent on is that MMR -- measles, mumps and rubella -- vaccinations do not appear to cause autism. A study from the late 1990s suggested a link between MMR and autism, though follow-up studies have failed to find such a connection. Some medical researchers continue to search for evidence to support a MMR-autism link.
    glavine@sltrib.com