Autism rates have been steadily increasing across the US for decades – but nowhere so steeply as in New Jersey, according to a new report.
While modest increases were seen in five other states tracked by the Centers for Disease Control and Prevention (CDC) report, there has been a staggering 43 percent increase in autism among four-year-olds in just four years.
Awareness of autism has certainly increased and New Jersey has some of the most reliable data on the disorder, but the report’s authors say that these factors aren’t nearly enough to explain such a sharp rise.
What does explain New Jersey’s high and growing rates of autism remains a mystery.
One in every 35 children in New Jersey is on the autism spectrum, and rates among four-year-olds have increased by 43 percent in four years there, a new CDC report finds
Nationwide, between one in 40 and one in 59 children has autism, depending on which estimate you look at.
In New Jersey, it’s one in 35.
Across the seven states included in the new CDC study – Arizona, Colorado Missouri, North Carolina, Utah and Wisconsin, in addition to New Jersey – autism rates climbed by about 27 percent between 2010 and 2014.
Taken together, the average autism rate is 1.7 percent of four-year-old children.
But in New Jersey, it’s three percent – up from one percent in 2000, and marking a 43 percent between 2010 and 2014.
The difference between a 27 percent increase and 43 percent increase is significant and, in this case, difficult to explain.
Autism as we know it – a diverse set of behavioral conditions on a spectrum – got its first recognition in 1994 in the Diagnostic and Statistical Manual of Mental Disorders (DSM) 4.
Because it described several subsets of characteristics to be treated uniquely, doctors started to learn more about the spectrum of disorders and diagnose more children with autism.
‘As with any new invention or discovery, there are early adopters that take it on right away, then the bulk will take more time, so you expect rates to vary upward slightly with growing awareness,’ says study co-author Dr Walter Zahorodny, a professor of pediatrics at Rutgers University.
‘About 10 to 20 percent [of upward variation] could be explained by better awareness, so you might see a change of say 1.1 percent to 1.4 percent over four years, and then it would stabilize.
‘But there’s no reason for it to vary so many years into the use [of the DSM 4 and 5 criteria], and still people are using that “better awareness” as if it was going to explain a change of 150 percent [since 2000].’
Autism is thought to begin with a genetic predisposition – so far, scientists have linked about 65 genes to the spectrum of disorders – and then get ‘triggered’ by environmental factors.
From there the possibilities become virtually endless.
The most substantial environmental links have been between autism and perinatal exposures, or things that happen while a baby is in the womb and just after their birth, including contact with pollution, having older parents, being a twin or multiple, premature birth, NICU stays and more.
Dr Zahorodny and his research team compared data on the perinatal risk factors faced by the children in their study to the data on rates of autism.
‘A number of these factors involved with elevated risk of autism…are all independently or semi-independently risk factors for autism,’ says Dr Zahorodny.
‘However, all of them taken together don’t seem to add up to a magnitude of increase in prevalence like we saw.
‘Altogether [perinatal factors] might account for five to 10 percent of the total number, but they’re not enough to move the prevalence from one to three percent.’
For eight-year-olds, the rate at all sites has increased by 150 percent since 2000.
But the surge among four-year-olds, who often don’t have clear clinical symptoms yet, was an odd phenomenon and, rather unique to New Jersey out of the seven states.
Missouri had the lowest prevalence of autism, and there were no significant changes in it or any of the other states besides New Jersey.
But there’s no clear explanation for the anomaly in New Jersey.
‘There’s something that might vary and cause rates to increase, something that would affect the broadest populations – all children, all backgrounds and regions seem to be effected – but I’m not even sure I have any good hypotheses about what it was,’ Dr Zahorodny says.
For now, our best response to the finding is for everyone to have an eye out for autism, Dr Zahorodny says.
‘If you have any question about your child’s development between 18 and 30 months, bring it to your pediatrician or family practitioner’s attention,’ he suggests.
‘And if you’re an activating person, who wants to try to get other people to do something positive, try to get [your doctor] o use an autism screener for all children, not just sporadically, but for all children.’