The number of New Zealanders diagnosed with autism spectrum disorder (ASD) has more than tripled over the past 15 years, with researchers warning the country’s health and disability services need to prepare for continued growth in demand.
The University of Otago Faculty of Medicine – Christchurch Ōtautahi-led study, published in The Australian and New Zealand Journal of Psychiatry, is the first to examine autism diagnosis trends across both children and adults in New Zealand. The study has found no evidence that the increase is slowing.
Associate Professor Ben Beaglehole
Led by Associate Professor Ben Beaglehole, from Otago’s Department of Psychological Medicine, the research analysed three national health and disability databases between 2009 and 2023, creating the most comprehensive picture yet of autistic spectrum disorder (ASD) prevalence across the New Zealand population.
The researchers found autism prevalence and the frequency of new diagnoses increased more than threefold during the study period. By 2023, 1.3 per cent of New Zealand children and 0.14 per cent of adults had an ASD diagnosis recorded in national databases, with increases recorded across all age groups, genders and ethnicities.
Associate Professor Beaglehole says the findings reflect international trends but carry important implications for Aotearoa New Zealand.
“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,” he says.
More than 30,800 people with ASD were identified during the study period. Most diagnoses were recorded through the national disability support database, highlighting the increasing demand for disability services alongside health care.
Associate Professor Beaglehole says one of the study’s most significant findings was the continuing rise in adult diagnoses.
“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.
“We’re also seeing adults who are receiving a diagnosis later in life. That means adult health services need to build greater expertise and capacity to support this growing population,” he adds.
The study also found ASD diagnoses remained more common among males, although diagnoses among females had increased at a faster rate than males over the 15-year period.
Researchers also observed marked changes among Māori. Diagnosis rates, initially lower than for non-Māori in 2009, increased almost fivefold and had overtaken non-Māori by 2023. Higher diagnosis rates were also seen in more socio economically deprived communities.
While the study was not designed to identify why ASD diagnoses are increasing, Associate Professor Beaglehole says the reasons are likely to be complex.
“It’s unlikely there’s a single explanation. Increased awareness, broader diagnostic criteria, better access to assessment and changing patterns of healthcare use are all likely to be contributing. There may also be broader environmental and societal influences that we don’t yet fully understand,” he suggests.
The research also found increasing numbers of pre-school children are being diagnosed, suggesting autism is being recognised earlier. At the same time, adult diagnoses continued to rise steadily throughout the study period, indicating many people are still being diagnosed later in life.
Associate Professor Beaglehole says the findings should prompt long-term planning across New Zealand’s 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.”
The researchers conclude the increase in autism diagnoses is unlikely to be explained by genetic change alone. Instead, they suggest multiple interconnected social, environmental and healthcare factors are contributing to the upward trend.
Publication:
Autism Spectrum Disorder trends for children and adults in New Zealand: a longitudinal examination of three national databases
Professor Ben Beaglehole, Dr Gordon Lu, Professor Chris Frampton
The Australia and New Zealand Journal of Psychiatry
https://doi.org/10.1177/00048674261472427
