At the age of 78, Bob Branham, a retired computer software developer in Dallas, Tex., took up quilting. It wasn't his idea, actually. He'd never dreamed of piecing together his own Amish diamond coverlet or rummaging around Jo-Ann Fabrics in search of calico prints. But then he enrolled in a trial sponsored by the National Institute on Aging to assess whether learning a new skill can help preserve cognitive function in old age. By random assignment, he landed in the quilting group.