Imagine a four-year-old who can draw the entire world map from memory, including the name of each country and ocean, but who resists playing with other children. Then imagine a seven-year-old who constantly rocks back and forth and is unable to speak. Despite their seeming differences, both children share a diagnosis of autism spectrum disorder (ASD), a neurological condition linked with a wide range of developmental delays, including challenges with social interaction, communication and repeated behaviors or restricted interests. Many kids with ASD also have trouble processing sensory information, finding some seemingly normal noises, tastes or textures intolerable.

Autism Spectrum Disorders affect about one in 150 children, according to The U.S. Centres for Disease Control and Prevention. (It hits boys four times as often as girls, too.) While some argue that these numbers are rising, that may be partly due to better awareness and diagnostic tools. “We’re diagnosing milder cases than we were 30 or 40 years ago,” says Dr. Catherine Lord, director of the University of Michigan Autism and Communication Disorders Center (UMACC) in Ann Arbor. The growing number of kids diagnosed with PDD-NOS (Persistent Developmental Disorder – Not Otherwise Specified), who display autistic symptoms but don’t fit all the diagnostic criteria, may also be behind the increase, suggests Dr. Laurent Mottron of the Pervasive Developmental Disorders Specialized Clinic at Riviere-des-Prairies Hospital in Montreal, Canada.