Socioeconomic status and the risk of suspected autism spectrum disorders among 18-month-old toddlers in Japan: A population-based study

INTRODUCTION:  Most of previous studies from the United States have reported a positive association between high family socioeconomic status (SES) and autism spectrum disorders (ASD) in children. The positive association between SES and ASD might be due to the healthcare system. Thus, the association between family SES and the suspected ASD status of 18-month-old toddlers was investigated using a population-based sample in Japan, which has a universal healthcare system and a mandatory health checkup system for toddlers.

METHODS:  Questionnaires were mailed to all families with 18-month-old toddlers in Chiba, a city near Tokyo (N = 6061; response rate: 64%). For SES assessment, both maternal and paternal education and annual household income were assessed. Suspected ASD was evaluated via questionnaire using the Japanese version of Modified Checklist for Autism in Toddlers, rated by mothers. Logistic regression was used to calculate the odds ratio of suspected ASD for each SES measure.

RESULTS:  The results of logistic regression analysis (which were adjusted for potential confounders) indicated that low maternal education, but not paternal education or family income, were associated with having suspected ASD offspring. Offspring of mothers who graduate high school or less was 1.36 (95% confidence interval: 1.08–1.71) times more likely to have suspected ASD than offspring of mothers who graduate college or more, regardless paternal education or household income, and other covariates.

CONCLUSIONS:  Lower maternal education was associated with an increased risk of autistic traits in Japan.