Abstract
Background: Autism spectrum disorder rates are rising internationally, although most studies only report prevalence rates for children, with limited data available for adults. We were interested in whether a similar trend is present in New Zealand and wished to report autism spectrum disorder data for adults.
Method: We analysed three large national databases to report population-adjusted rates of autism spectrum disorder in New Zealand between 2009 and 2023. Rates were analysed according to child (<18 years) and adult (18 years and over) populations, as well as by gender and ethnicity. The frequency of newly identified cases in the databases was also reported.
Results: Autism spectrum disorder prevalence and the frequency of newly identified cases increased threefold during the study period. By 2023, the rate of autism spectrum disorder diagnoses in the New Zealand population was 1.3% for children and 0.14% for adults. Autism spectrum disorder was more common among males and in more deprived areas. Māori rates of autism spectrum disorder were lower than non-Māori rates in 2009 but increased nearly fivefold, and this finding reversed by 2023.
Conclusion: Autism spectrum disorder is becoming more common in New Zealand. The increase occurred for child and adult populations and shows no sign of abating. Healthcare and disability services should prepare for increased demand by people with autism spectrum disorder through enhanced education, service planning, and additional resources.