Diagnoses of autism spectrum disorder in New Zealand have more than tripled over 15 years, according to a University of Otago study released this week, and the researchers behind it say the health and disability system should be planning for demand that keeps climbing rather than levelling off.
The work was led by Associate Professor Ben Beaglehole of Otago’s Department of Psychological Medicine and drew on three national health and disability databases covering 2009 to 2023. It identified more than 30,800 people with a recorded autism diagnosis across that period. By 2023, 1.3 per cent of New Zealand children and 0.14 per cent of adults had an autism diagnosis recorded somewhere in the national data. The findings were published in the Australian and New Zealand Journal of Psychiatry and reported by RNZ and 1News.
It is the first study to follow autism diagnosis trends across both children and adults in this country. Almost everything published before it has stopped at the school gate, which is part of the reason the adult figures in this study matter so much. They describe a group that has been largely invisible in the planning of New Zealand health services.
The increase showed up everywhere the researchers looked. Rates rose across every age group, both sexes and every ethnic group in the data. Autism remains more commonly diagnosed in males, but diagnoses among females climbed faster over the 15 years, narrowing a gap that clinicians have long suspected was an artefact of how the condition was first described rather than a real difference in who has it. Diagnosis rates were also higher in more socioeconomically deprived communities.
Diagnosis rates for Māori started the period lower than for non-Māori, increased almost fivefold, and had overtaken non-Māori by 2023. The most straightforward reading of that is not a change in who is autistic but a change in who is getting assessed. A population that was previously under-served has caught up and, on these numbers, passed the rest of the country.
Beaglehole was clear that the study does not describe a sudden epidemic. He put the rise down to “greater awareness, broader diagnostic criteria and better access to assessment”, and pointed out that recorded rates of ADHD and psychological distress have moved in the same direction over a similar period, which suggests “there are broader factors at play” than anything specific to autism.
That distinction is easy to lose in a headline and worth holding on to. What these databases record is a diagnosis, not a condition. A person who was autistic in 2009 and never assessed does not appear in the 2009 figure. The same person assessed in 2022 appears in the 2022 figure. Much of the growth in the chart is therefore the system finding people it used to miss, which is a sign of something working rather than something going wrong.
The advocacy and information service Altogether Autism made the same point in its own analysis of national data in July, noting that increases over time “are therefore best understood as reflecting improved recognition, access and recording rather than a sudden rise in autism itself”. Its figures showed identified autism among New Zealanders aged under 25 rising from about 11,500 people in 2014/15 to more than 27,500 in 2023/24, and the male to female ratio narrowing from roughly four to one down to closer to three to one.
The finding with the sharpest practical edge is the one about adults. Beaglehole said autism “has traditionally been viewed as a childhood condition from a research perspective, however, it is in fact a lifelong disorder”, and the study records a continuing rise in people receiving a first diagnosis well into adulthood. New Zealand has built most of its autism expertise around children, in paediatric clinics, in schools and in early intervention services. An adult who is assessed at 35 or 50 lands in a part of the system that has far less experience with them and, in many districts, no obvious front door at all.
That is the capacity question the researchers are pushing. If diagnoses keep rising and a growing share of them are adults, then general practice, adult mental health services, employers and tertiary institutions all inherit demand that was previously handled, or simply not handled, elsewhere. Nothing in the 15 years of data suggests the curve is flattening.
The study lands about three weeks after New Zealand’s first national report on neurodevelopmental conditions, Kanorau ā-roro, which we covered here in July. That report looked at children and found the opposite problem to the one a tripling figure might imply. Service-identified rates for autism in New Zealand children sat at about 1 per cent against international estimates of 1 to 2 per cent, and rates for ADHD sat well below the global benchmark, with rural children, children in deprived areas and girls waiting longest or missing out altogether. Diagnosis delays of up to three years separated one district from another.
Read together, the two pieces of work describe the same system from opposite ends. Recognition has improved enormously since 2009. It still has not caught up with the number of people who would meet the criteria, and where you live and who you are still shape how long you wait. A tripling in 15 years is not evidence that too many people are being diagnosed. On the international comparisons, it is evidence that the country started from a long way behind.
What happens next is largely a resourcing decision rather than a scientific one. The data now exists to show where the assessments are happening, who is getting them and how old people are when they finally get an answer. Whether adult services are built to meet what that data describes is up to the people who set the health budget.
Have you or someone in your family been diagnosed as an adult, and how long did it take to get there? Tell us in the comments below.
This article was written by AI, briefed to report the facts, hopefully without some of the bias people bring to the job 🙂
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