Rates of autism spectrum disorder diagnoses are still rising in the US, according to a new report published by the nation's Center for Disease Control and Prevention (CDC), contradicting earlier estimates that optimistically concluded it was levelling off.
In spite of significant progress being made on understanding the underlying physiology of this diverse condition, researchers aren't entirely sure what's behind these fluctuations, and whether we should be concerned or relieved.
Since 2007, the CDC's Autism and Developmental Disabilities Monitoring Network has collected data on autism diagnoses from 11 US states, shining a light on a trend that shows either the condition is becoming more common or we're getting better at spotting it.
The last two reports based on evidence collected in 2010 and 2012 suggested rates had plateaued at one in every 68 children of 8 years of age, up from one in 88 children in 2008 and one in 110 two years earlier.
A study published earlier this year looking broadly at the evidence also concluded the rate seemed to have flat-lined in recent years.
Yet these latest CDC figures based on data collected in 2014 suggest we need to stay cautious and refrain from claiming an end to the rise, finding a jump to one in just 59 children.
That's a 15 percent increase compared with the results of previous reports.
Autism Spectrum Disorder, or ASD, is an umbrella term for neurological conditions that impede communication and social skills, while also influencing other physiological traits such as motor control and core body strength.
While there might be early signs, diagnoses aren't considered conclusive until a child is around two to three years of age, when all-important stages in development are expected to have been reached.
The majority of children diagnosed in the state of Maryland, for example, were found to show early hints of developmental concerns. Yet barely half of these children had been diagnosed by age three, pointing at a gap that might go some way to explaining the overall rate of diagnosis.
"This lag may delay the timing for children with ASD to get diagnosed and to start receiving needed services," says psychiatric epidemiologist Li-Ching Lee from the Bloomberg School's departments of Epidemiology and Mental Health.
Right now there are no commercially available biological marker tests or definitive brain scans that can identify which newborns are likely to exhibit ASD traits later in life.
Thanks to this, and the fact it is a wide spectrum, children and even adults with borderline criteria are easily being overlooked.
Increased awareness among new parents and early childcare practitioners go a long way in explaining why we're seeing more children with an ASD diagnosis, putting a positive spin on the trend.
Higher numbers don't mean more children with ASD – they mean we're simply seeing what would once have flown under the radar.
This is especially encouraging among minorities who in the past might have missed out on the assistance that comes with a diagnosis.
Previous research by the CDC reported ASD was 20 to 30 percent more common among children from a white background than non-Hispanic black children.
This new report has seen the difference drop to just 7 percent.
"Although we continue to see disparities among racial and ethnic groups, the gap is closing," says Lee.
Whether awareness and improved access completely explains all of the numbers, though, remains an open question.
Genetics is understood to play a strong role in autism's development, though not all genetic variations are of the inherited variety.
Some are external 'epigenetic' edits made prior to, or even after, conception. Other spontaneous mutations have also been linked to some of autism's characteristics.
There are some statistical hints that certain environmental factors could also have a hand in the condition.
What all of this adds up to is a complex picture of a complicated disorder.
These latest results are by no means the last word on ASD, and still need to be considered as part of a bigger picture. Over all, we have a lot to be optimistic about.
Even without solid answers, having these statistics is a vital step forward in developing a better understanding of the condition.
The ADDM Network report can be found on the CDC website.