Why Are Autism Rates Steadily Rising?

Why Are Autism Rates Steadily Rising?

Stefania Sterling with her son Charlie, who was diagnosed at age 3 with autism.

(Courtesy)



Stefania Sterling was just 21 when she had her son, Charlie. She was young and healthy, with no genetic issues apparent in either her or her husband's family, so she expected Charlie to be typical.

"It is surprising that the prevalence of a significant disorder like autism has risen so consistently over a relatively brief period."

It wasn't until she went to a Mommy and Me music class when he was one, and she saw all the other one-year-olds walking, that she realized how different her son was. He could barely crawl, didn't speak, and made no eye contact. By the time he was three, he was diagnosed as being on the lower functioning end of the autism spectrum.

She isn't sure why it happened – and researchers, too, are still trying to understand the basis of the complex condition. Studies suggest that genes can act together with influences from the environment to affect development in ways that lead to Autism Spectrum Disorder (ASD). But rates of ASD are rising dramatically, making the need to figure out why it's happening all the more urgent.

The Latest News

Indeed, the CDC's latest autism report, released last week, which uses 2016 data, found that the prevalence of ASD in four-year-old children was one in 64 children, or 15.6 affected children per 1,000. That's more than the 14.1 rate they found in 2014, for the 11 states included in the study. New Jersey, as in years past, was the highest, with 25.3 per 1,000, compared to Missouri, which had just 8.8 per 1,000.

The rate for eight-year-olds had risen as well. Researchers found the ASD prevalence nationwide was 18.5 per 1,000, or one in 54, about 10 percent higher than the 16.8 rate found in 2014. New Jersey, again, was the highest, at one in 32 kids, compared to Colorado, which had the lowest rate, at one in 76 kids. For New Jersey, that's a 175 percent rise from the baseline number taken in 2000, when the state had just one in 101 kids.

"It is surprising that the prevalence of a significant disorder like autism has risen so consistently over a relatively brief period," said Walter Zahorodny, an associate professor of pediatrics at Rutgers New Jersey Medical School, who was involved in collecting the data.

The study echoed the findings of a surprising 2011 study in South Korea that found 1 in every 38 students had ASD. That was the the first comprehensive study of autism prevalence using a total population sample: A team of investigators from the U.S., South Korea, and Canada looked at 55,000 children ages 7 to 12 living in a community in South Korea and found that 2.64 percent of them had some level of autism.

Searching for Answers

Scientists can't put their finger on why rates are rising. Some say it's better diagnosis. That is, it's not that more people have autism. It's that we're better at detecting it. Others attribute it to changes in the diagnostic criteria. Specifically, the May 2013 update of the Diagnostic and Statistical Manual of Mental Disorders-5 -- the standard classification of mental disorders -- removed the communication deficit from the autism definition, which made more children fall under that category. Cynical observers believe physicians and therapists are handing out the diagnosis more freely to allow access to services available only to children with autism, but that are also effective for other children.

Alycia Halladay, chief science officer for the Autism Science Foundation in New York, said she wishes there were just one answer, but there's not. While she believes the rising ASD numbers are due in part to factors like better diagnosis and a change in the definition, she does not believe that accounts for the entire rise in prevalence. As for the high numbers in New Jersey, she said the state has always had a higher prevalence of autism compared to other states. It is also one of the few states that does a good job at recording cases of autism in its educational records, meaning that children in New Jersey are more likely to be counted compared to kids in other states.

"Not every state is as good as New Jersey," she said. "That accounts for some of the difference compared to elsewhere, but we don't know if it's all of the difference in prevalence, or most of it, or what."

"What we do know is that vaccinations do not cause autism."

There is simply no defined proven reason for these increases, said Scott Badesch, outgoing president and CEO of the Autism Society of America.

"There are suggestions that it is based on better diagnosis, but there are also suggestions that the incidence of autism is in fact increasing due to reasons that have yet been determined," he said, adding, "What we do know is that vaccinations do not cause autism."

Zahorodny, the pediatrics professor, believes something is going on beyond better detection or evolving definitions.

"Changes in awareness and shifts in how children are identified or diagnosed are relevant, but they only take you so far in accounting for an increase of this magnitude," he said. "We don't know what is driving the surge in autism recorded by the ADDM Network and others."

He suggested that the increase in prevalence could be due to non-genetic environmental triggers or risk factors we do not yet know about, citing possibilities including parental age, prematurity, low birth rate, multiplicity, breech presentation, or C-section delivery. It may not be one, but rather several factors combined, he said.

"Increases in ASD prevalence have affected the whole population, so the triggers or risks must be very widely dispersed across all strata," he added.

There are studies that find new risk factors for ASD almost on a daily basis, said Idan Menashe, assistant professor in the Department of Health at Ben-Gurion University of the Negev, the fastest growing research university in Israel.

"There are plenty of studies that find new genetic variants (and new genes)," he said. In addition, various prenatal and perinatal risk factors are associated with a risk of ASD. He cited a study his university conducted last year on the relationship between C-section births and ASD, which found that exposure to general anesthesia may explain the association.

Whatever the cause, health practitioners are seeing the consequences in real time.

"People say rates are higher because of the changes in the diagnostic criteria," said Dr. Roseann Capanna-Hodge, a psychologist in Ridgefield, CT. "And they say it's easier for children to get identified. I say that's not the truth and that I've been doing this for 30 years, and that even 10 years ago, I did not see the level of autism that I do see today."

Sure, we're better at detecting autism, she added, but the detection improvements have largely occurred at the low- to mid- level part of the spectrum. The higher rates of autism are occurring at the more severe end, in her experience.

A Polarizing Theory

Among the more controversial risk factors scientists are exploring is the role environmental toxins may play in the development of autism. Some scientists, doctors and mental health experts suspect that toxins like heavy metals, pesticides, chemicals, or pollution may interrupt the way genes are expressed or the way endocrine systems function, manifesting in symptoms of autism. But others firmly resist such claims, at least until more evidence comes forth. To date, studies have been mixed and many have been more associative than causative.

"Today, scientists are still trying to figure out whether there are other environmental changes that can explain this rise, but studies of this question didn't provide any conclusive answer," said Menashe, who also serves as the scientific director of the National Autism Research Center at BGU.

"It's not everything that makes Charlie. He's just like any other kid."

That inconclusiveness has not dissuaded some doctors from taking the perspective that toxins do play a role. "Autism rates are rising because there is a mismatch between our genes and our environment," said Julia Getzelman, a pediatrician in San Francisco. "The majority of our evolution didn't include the kinds of toxic hits we are experiencing. The planet has changed drastically in just the last 75 years –- it has become more and more polluted with tens of thousands of unregulated chemicals being used by industry that are having effects on our most vulnerable."

She cites BPA, an industrial chemical that has been used since the 1960s to make certain plastics and resins. A large body of research, she says, has shown its impact on human health and the endocrine system. BPA binds to our own hormone receptors, so it may negatively impact the thyroid and brain. A study in 2015 was the first to identify a link between BPA and some children with autism, but the relationship was associative, not causative. Meanwhile, the Food and Drug Administration maintains that BPA is safe at the current levels occurring in food, based on its ongoing review of the available scientific evidence.

Michael Mooney, President of St. Louis-based Delta Genesis, a non-profit organization that treats children struggling with neurodevelopmental delays like autism, suspects a strong role for epigenetics, which refers to changes in how genes are expressed as a result of environmental influences, lifestyle behaviors, age, or disease states.

He believes some children are genetically predisposed to the disorder, and some unknown influence or combination of influences pushes them over the edge, triggering epigenetic changes that result in symptoms of autism.

For Stefania Sterling, it doesn't really matter how or why she had an autistic child. That's only one part of Charlie.

"It's not everything that makes Charlie," she said. "He's just like any other kid. He comes with happy moments. He comes with sad moments. Just like my other three kids."

Caren Chesler
Caren Chesler is an award-winning journalist whose work has appeared in The New York Times, Scientific American, Slate, Salon, and Popular Mechanics. She has a blog called The Dancing Egg, about having a baby at 47 through IVF.
Why we need to get serious about ending aging

With the population of older people projected to grow dramatically, and the cost of healthcare with it, the future welfare of the country may depend on solving aging, writes philosopher Ingemar Patrick Linden.

Photo by Alessio Lin on Unsplash

It is widely acknowledged that even a small advance in anti-aging science could yield benefits in terms of healthy years that the traditional paradigm of targeting specific diseases is not likely to produce. A more youthful population would also be less vulnerable to epidemics. Approximately 93 percent of all COVID-19 deaths reported in the U.S. occurred among those aged 50 or older. The potential economic benefits would be tremendous. A more youthful population would consume less medical resources and be able to work longer. A recent study published in Nature estimates that a slowdown in aging that increases life expectancy by one year would save $38 trillion per year for the U.S. alone.

A societal effort to understand, slow down, arrest or even reverse aging of at least the size of our response to COVID-19 would therefore be a rational commitment. In fact, given that America’s older population is projected to grow dramatically, and the cost of healthcare with it, it is not an overstatement to say that the future welfare of the country may depend on solving aging.

This year, the kingdom of Saudi Arabia has announced that it will spend up to 1 billion dollars per year on science with the potential to slow down the aging process. We have also seen important investments from billionaires like Google co-founder Larry Page, Amazon founder Jeff Bezos, business magnate Larry Ellison, and PayPal co-founder Peter Thiel.

The U.S. government, however, is lagging: The National Institutes of Health spent less than one percent of its $43 billion budget for the fiscal year of 2021 on the National Institute on Aging’s Division of Aging Biology. When you visit the division’s webpage you find that their mission statement carefully omits any mention of the possibility of slowing down the aging process.

Keep Reading Keep Reading
Ingemar Patrick Linden
Driven by a passion to probe the fundamental questions we are confronted with, Dr. INGEMAR PATRICK LINDEN has been on a journey of discovery taking him from Lund University in Sweden, to UCL in London, to University of California, to New York, where he has taught philosophy for almost a decade. Death. It does not get more fundamental than that. One of the ideas that has remained a firm conviction of the author’s since childhood is that we do not have enough time. We are but the beginnings of complete humans, fragments of what we could be. It was the realization that not all share this view, in fact, surveys show that most do not, that inspired, and necessitated, the writing of THE CASE AGAINST DEATH.
Could a tiny fern change the world — again?

A worker tends to a rural farm in Hanoi, Vietnam, where technology is making it easier to harvest an ancient fern called Azolla. Some scientists and farmers view Azolla as a solution to our modern-day agricultural and environmental challenges.

Pham Gia Minh

More than 50 million years ago, the Arctic Ocean was the opposite of a frigid wasteland. It was a gigantic lake surrounded by lush greenery brimming with flora and fauna, thanks to the humidity and warm temperatures. Giant tortoises, alligators, rhinoceros-like animals, primates, and tapirs roamed through nearby forests in the Arctic.

This greenhouse utopia abruptly changed in the early Eocene period, when the Arctic Ocean became landlocked. A channel that connected the Arctic to the greater oceans got blocked. This provided a tiny fern called Azolla the perfect opportunity to colonize the layer of freshwater that formed on the surface of the Arctic Ocean. The floating plants rapidly covered the water body in thick layers that resembled green blankets.

Gradually, Azolla colonies migrated to every continent with the help of repeated flooding events. For around a million years, they captured more than 80 percent of atmospheric carbon dioxide that got buried at the bottom of the Arctic Ocean as billions of Azolla plants perished.

Keep Reading Keep Reading
Anuradha Varanasi
Anuradha Varanasi is a freelance science journalist based in Mumbai, India. She has an MA in Science Journalism from Columbia University in the City of New York. Her stories on environmental health, biomedical research, and climate change have been published in Forbes, UnDark, Popular Science, and Inverse. You can follow her on Twitter @AnuradhaVaranas