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.
Signs of autism may appear during infancy and the disorder is usually diagnosed by the age of 3. Sometimes the child's development appears normal until about 2 years old and then regresses rapidly. Symptoms of autism occur in various combinations, from mild to severe.