Increasing incidence mirrors alarming global trends
By Jill Escher
Okaya is a city located in central Japan with a population of approximately 50,000.
A new study by Daimei Sasayama et al. of Shinshu University School of Medicine, and published in the Journal of Autism and Developmental Disorders, indicates that after thorough screening 3% of the city’s children have autism.
The researchers evaluated the follow-ups of 1067 (517 boys and 550 girls) six year-olds who had also undergone a screening for ASD at there routine 18-months health checkup. In Japan, a health checkup is performed for all children at 18 months. The study subjects were children born between April 2009 and April 2012.
This study had two main objectives: (1) to present the cumulative incidence of ASD in an area with a thorough screening system, and (2) to examine the behavioral and motor characteristics observed at the age of 18 months in children later diagnosed as ASD.
Retrospectively, the questionnaire answered by caregivers at the 18-month-old checkup suggested that children later diagnosed with ASD showed delay in fine motor and gross motor skills and social and communication skills.
By the age of 6 years, 3.1% (4.3% of boys and 2.0% of girls) were diagnosed as having ASD by their attending pediatricians.
A similar incidence rate was reported in another cohort in Japan (Hamamatsu Birth Cohort for Mothers and Children) last year, where 3.1% of 952 children aged 32 months were found to have autism.
The study is consistent with global trends showing increasing autism rates among children. For example, nearly 2% of U.S. 8-year-old children were reported to have ASD based on CDC data. Northern Ireland reports a rate of 3.2% of schoolchildren. Recent Denmark data showed incidence may exceed 2.8%.
Other findings of the Okayashi study include:
• No significant difference in maternal or paternal age at birth was observed between ASD and non-ASD children.
• No significant difference between ASD and non-ASD children was present in birthweight or head circumference at birth (controlling for sex) or at the 18-month checkup.
You can find the study (paywalled) here.