Autism is one of three diagnoses that the DSM-5 includes in autism spectrum disorder (ASD). While our understanding of this condition has grown exponentially, research has been fraught with controversy. Autism appears to be on the rise, depending on how you define it, and its causes more complex than imagined. In Understanding Autism, Scientific American's editors have gathered the most current information on autism, including how it's diagnosed, risk factors, treatments, and therapies.