Is Michael Phelps autistic?

Michael Phelps is an Olympic swimmer from the United States who has the distinction of being the most decorated Olympian of all time, with 22 medals.  He was diagnosed with attention deficit hyperactivity disorder (ADHD) in sixth grade, and began swimming as an outlet for his excess energy.  In 2008, he became an honorary board member of Pathfinders for Autism, an organization that helps families raising children with autism find appropriate resources.  While many argue that ADHD could be on the lower level of the autism spectrum, there is no confirmation that Michael Phelps has autism.

Does Metta World Peace have autism?