Autism diagnoses in New Zealand have more than tripled over the last 15 years, according to a longitudinal study published in The Australian and New Zealand Journal of Psychiatry. Researchers at the University of Otago analyzed national health databases between 2009 and 2023, warning that health and disability services must prepare for continued growth in demand.
University of Otago Study Details Rapid Rise Across National Databases
When researchers examined three national health and disability databases covering the period from 2009 to 2023, they uncovered a massive shift in how autism is recorded across the country. Led by Associate Professor Ben Beaglehole from Otago’s Department of Psychological Medicine, the research created the most comprehensive picture yet of autistic spectrum disorder prevalence across the New Zealand population.
More than 30,800 people with ASD were identified during the study window. By 2023, national databases showed that 1.3 percent of New Zealand children and 0.14 per cent of adults held a formal diagnosis. Increases appeared across every age bracket, gender, and ethnic group, mirroring broader international patterns while posing unique domestic challenges.
“While we’ve known autism diagnosis rates in children have been increasing, our study shows the same pattern is also occurring in adults, and we found no evidence the trend is beginning to plateau.”
Ben Beaglehole, Associate Professor in Otago’s Department of Psychological Medicine
Shifting Demographics: Adult Diagnoses, Gender Gaps, and Māori Rates
While autism remains diagnosed more frequently in males, diagnoses among females accelerated at a faster pace than among males over the 15-year study timeframe. Adult diagnoses also climbed steadily, pointing to many people who are receiving a diagnosis later in life.
Researchers observed a striking transformation within Māori communities. In 2009, diagnosis rates among Māori trailed those of non-Māori. By 2023, however, those rates had surged almost fivefold, ultimately overtaking non-Māori figures. Higher diagnosis rates also emerged in socio-economically deprived communities, alongside an increase in pre-school diagnoses indicating that autism is being recognized earlier in life.
“Autism has traditionally been viewed as a childhood condition from a research perspective. However, it is in fact a lifelong disorder, with demand likely to occur throughout the lifespan.”
Ben Beaglehole, Associate Professor in Otago’s Department of Psychological Medicine
Healthcare Planning and the Drivers Behind the Numbers
The study did not set out to pinpoint a single catalyst for the surge, and Beaglehole emphasized that it’s unlikely there’s a single explanation. Instead, researchers point to a combination of heightened public awareness, broader diagnostic criteria, improved access to assessments, and changing patterns of healthcare utilization. Environmental and societal influences that remain poorly understood likely play a role as well, though genetic shifts alone cannot account for the trajectory.
Most diagnoses during the study period were logged through the national disability support database, underlining how tightly healthcare needs intertwine with broader disability services. With adult health services needing to build greater expertise and capacity for this growing population, researchers urge long-term planning across health and disability sectors.
“Our results suggest increasing demand for autism-related services is likely to continue. That means investing in workforce training, improving service planning and ensuring both child and adult services are equipped to provide appropriate care.”
Ben Beaglehole, Associate Professor in Otago’s Department of Psychological Medicine
