(Reuters) - As many as one in 50 U.S. school-age children have a diagnosis of autism, up from one in 86 in 2007, with much of the increase involving milder cases, suggesting the rise is linked to growing awareness and better testing methods, government researchers said on Wednesday.
In line with previous estimates, boys in the study were four times more likely to be diagnosed with autism than girls, according to the study, which is based on American parent reports of autism diagnoses in 2011-12 compared with 2007.
Autism can range from highly functioning individuals to those with severe speech and intellectual disabilities, in general individuals struggle with difficulties in communication, behavior and social interaction.
According to the study by the U.S. Department of Health and Human Services and the Centers for Disease Control and Prevention, much of the increase in the estimates was the result of diagnoses of children with previously unrecognized autism.
Symptoms of autism can be seen in children as young as 18 months of age, and doctors are urged to conduct a screening for developmental delays on all children by age 2. But doctors often fail to detect mild cases of autism until children enter school, when parents become aware of their child's troubles making friends and teachers notice differences in the child's ability to interact socially, the team said.
Increased awareness of autism differences in children may help account for the increased diagnoses in school-age children, the team said.
While scientists believe genetics account for 80 percent to 90 percent of the risk for developing autism, most cases of autism cannot be traced to a known inherited cause.
Reporting by Julie Steenhuysen; Editing by Doina Chiacu