Analysis using a national medical database revealed that the cumulative incidence of autism spectrum disorders (ASD) in children born in 2009-2014 was 2.75% by the age of five. A research group led by Associate Professor Daimei Sasayama and Professor Hideo Honda of the Department of Child and Adolescent Development Psychiatry, Shinshu University School of Medicine, used a national medical database to analyze autism spectrum disorders in Japan. It was reported that the cumulative incidence showed an increasing trend for each year of birth, and that there were regional differences.