Autism Spectrum Disorder: Incidence of Diagnosis in Japan One of Highest in World Interview with:
Daimei Sasayama, M.D., Ph.D.

Department of Psychiatry
Shinshu University What is the background for this study?

Response: The diagnosis of autism spectrum disorder (ASD) is increasing worldwide. A 2016 US survey reported a prevalence of 1.85% in 8-year-olds, and a birth cohort study in Denmark reported that the future cumulative incidence of ASD could exceed 2.8%.

Our recent regional cohort study in Japan reported an even higher cumulative incidence of 3.1%. So we examined whether the cumulative incidence in our regional cohort represents the nationwide incidence in Japan. What are the main findings?

Response: We investigated the nationwide cumulative incidence of ASD using the National Database of Health Insurance Claims of Japan, which aggregates medical data from all over the country. Of the children born in 2009-2016, 313,353 were diagnosed with ASD in 2009-2019. The lifetime cumulative incidence of ASD at age 5 in children born between 2009 and 2014 was 2.75%. The cumulative lifetime incidence in each prefecture ranged from 0.9 to 7.9%, indicating large regional variation. What should readers take away from your report?

Response: The cumulative incidence of autism spectrum disorder reported in our study is one of the highest in the world based on medical diagnosis. Our results suggest the high diagnostic sensitivity of ASD in Japan. Expanding public awareness is likely to have contributed substantially to the increased nationwide incidence. On the other hand, the large regional variation may be due to other factors such as differences in accessibility to services. Our findings point to an important need for further health services for supporting individuals with ASD. What recommendations do you have for future research as a result of this work?

Response: Continued investigation is needed to further elucidate the trends in the incidence of ASD and to identify the factors associated with the increased incidence. Although the rise in the ASD diagnosis is global, our study suggests that the incidence is especially high in Japan. Future research should examine the influence of sociodemographic and socioeconomic factors as well as race and ethnicity on the incidence and prevalence of ASD. 

Any disclosures?

Response: This study was funded by grant-in-aid for scientific research H30-shintai/chiteki-ippan-002 from the Ministry of Health, Labour, and Welfare. The funder had no role in the design and conduct of the study.


Sasayama D, Kuge R, Toibana Y, Honda H. Trends in Autism Spectrum Disorder Diagnoses in Japan, 2009 to 2019. JAMA Netw Open. 2021;4(5):e219234. doi:10.1001/jamanetworkopen.2021.9234



The information on is provided for educational purposes only, and is in no way intended to diagnose, cure, or treat any medical or other condition. Always seek the advice of your physician or other qualified health and ask your doctor any questions you may have regarding a medical condition. In addition to all other limitations and disclaimers in this agreement, service provider and its third party providers disclaim any liability or loss in connection with the content provided on this website.


Last Updated on May 28, 2021 by Marie Benz MD FAAD