These four events repeat every 'tropical' year (365 days, 5 hours, 49 minutes), so they become later by about six hours, or (if there has been an intervening leap day) earlier by about 18 hours, from one year to the next.
The three distinctive signs and symptoms of autism include problems with verbal and nonverbal communication, difficulties with social interaction, and repetitive behaviors or narrow, obsessive interests. There are three distinctive symptoms of autism.
Autism is one of five types of autism spectrum disorder. Autism spectrum disorders are developmental brain disorders. These disorders are characterized by impaired social interaction and communication skills, and a limited range of activities and interests. Other types of autism spectrum disorder include:1  Asperger syndrome.utism spectrum disorders are developmental brain disorders. These disorders are characterized by impaired social interaction and communication skills, and a limited range of activities and interests. Other types of autism spectrum disorder include: 1  Asperger syndrome.