Autism rates in Australian children are among the highest in the world, leading a senior researcher to suggest the National Disability Insurance Scheme (NDIS) could be driving steeper than average growth in diagnoses.
A paper by Australian National University scholar Maathu Ranjan, who is on study leave from her role as a senior actuary at the National Disability Insurance Agency that oversees the scheme, shows autism rates have risen notably in developed nations over the past 10 years.
But the increase has been sharper in Australia than in other countries with comparable economic and health systems such as the United States, Canada and the United Kingdom.
“Estimates of prevalence in Australia are some of the highest in the world and have grown faster than the global average,” Ranjan said.
“It is plausible that the growth of prevalence rates above the global average in Australia can be attributed to the financial incentives created by government policy, specifically the implementation of the NDIS.”
Her paper comes as federal and state governments mull an independent review of the NDIS, which is one of the federal government’s fastest-growing expenses.
The review was given to disability ministers this month but will not be publicly released until premiers and chief ministers discuss it at national cabinet later this year.
They will seek reforms to make the scheme more sustainable given projections that its annual cost will soar to more than $100 billion by 2032, in part due to a higher-than-forecast number of children joining with autism.
More than 75 per cent of NDIS participants under 18, and 45 per cent overall, have autism or developmental delay, which can often precede an autism diagnosis.
While the NDIS is delivering help to many who need it – particularly in regional and disadvantaged parts of the country where participation rates for children are highest – it has also been described as the “only lifeboat in the ocean”.
Some experts say that has skewed the way children are diagnosed with autism. More than 8 per cent of five-to seven-year-old children are now on the scheme.
Ranjan said neurodiversity and autism were no longer rare, and health, education and employment systems needed to reflect that – a view shared by NDIS architect Bruce Bonyhady, who is reviewing the scheme and has called for better support for children with autism in mainstream settings.
Ranjan’s research, which has not been peer-reviewed, quotes international studies that show autism prevalence rates of one in 36 children in the United States, one in 50 children in Canada, and one in 57 children in the United Kingdom. In Australia, it is about one in 25.
She said the Australian statistics were most similar to those in Japan, where early detection and intervention have been in place since the 1990s. Early intervention has been shown to have long-term positive effects on children’s symptoms and later skills.
But Ranjan said there was “considerable controversy” around the drivers of rising autism rates worldwide.
Some studies have suggested that changing criteria over decades and improved awareness have led to more people being diagnosed, or that some doctors might substitute an autism diagnosis for conditions that have overlapping symptoms, such as ADHD and dyslexia, so patients can access basic services.
There have also been twin studies suggesting genetic links, but the exact genetic causes of autism remain unknown.
Ranjan said the NDIS could be a factor that accounted for the difference in autism diagnoses between Australia and comparable countries.
“Incentives in government policy, specifically the NDIS, is the key factor unique to the Australian context and potentially explains the additional growth in Australian prevalence,” she wrote.
Her analysis of autism rates from the past decade showed they increased faster in the regions where the NDIS was being rolled out, suggesting the scheme had an impact on the number of people seeking a diagnosis.
But she said further work was needed to determine any causal effect. Despite spikes in prevalence in Australia coinciding with the NDIS, “there has been little research that evaluates the national impact of this policy on the prevalence of autism”.
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