An autistic boy holds the hand of his adoptive father as they prepare to leave for a family outing from their home in Springfield, Mass., on Saturday, Dec. 12, 2015. Traditionally, autism was diagnosed only in kids with severe language and social impairments and unusual repetitious behaviors. But the definition gradually expanded, and autism is now shorthand for a group of milder, related conditions, too. (AP Photo/Charles Krupa, File)
