Why Are Autism Rates Steadily Rising?
Stefania Sterling with her son Charlie, who was diagnosed at age 3 with autism.
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."
Slowing Aging Could Transform Society As We Know It
A young woman portrayed next to her old counterpart.
People's lives have been getting longer for more than a century. In 1900, in even the wealthiest countries, life expectancy was under 50, according to the World Health Organization. By 2015, the worldwide average was 74, and a girl born in Japan that year could expect to live to 87. Most of that extra lifespan came from improvements in nutrition and sanitation, and the development of vaccines and antibiotics.
People's lives have been getting longer for more than a century. In 1900, in even the wealthiest countries, life expectancy was under 50, according to the World Health Organization. By 2015, the worldwide average was 74, and a girl born in Japan that year could expect to live to 87. Most of that extra lifespan came from improvements in nutrition and sanitation, and the development of vaccines and antibiotics.
The question is, how will slowing aging change society?
But now scientists are trying to move beyond just eliminating the diseases that kill us to actually slowing the aging process itself. By developing new drugs to tackle the underlying mechanisms that make our bodies grow old and frail, researchers hope to give people many more years of healthy life. The question is, how will that change society?
There are several biological mechanisms that affect aging. One involves how cells react when they're damaged. Some die, but others enter a state called senescence, in which they halt their normal growth and send out signals that something's gone wrong. That signaling causes inflammation at the sight of a wound, for instance, and triggers the body's repair processes. Once everything is back to normal, the senescent cells die off and the inflammation fades. But as we age, the machinery for clearing senescent cells becomes less efficient and they begin to pile up. Some researchers think that this accumulation of senescent cells is what causes chronic inflammation, which has been implicated in conditions such as heart disease and diabetes.
The first clinical trial in humans of senolytic drugs is happening now.
In 2015, researchers at the Mayo Clinic in Minnesota and the Scripps Research Institute in Florida tested the first so-called senolytic drugs, which cause senescent cells to die. After the scientists treated mice with a combination of an anti-cancer drug and a plant pigment that can act as an antioxidant, some of the senescent cells shrank away and caused the mouse's heart function to revert to that of a much younger mouse.
"That suggests that senescence isn't just a consequence of aging, it's actually a driver of aging," says Paul Robbins, a professor of molecular medicine at Scripps and one of the researchers involved. Other animal studies have found that reducing the number of senescent cells improves a variety of age-related conditions, such as frailty, diabetes, liver disease, pulmonary fibrosis, and osteoporosis.
Now the same researchers are moving those tests to humans in the first clinical trials of senolytic drugs. In July 2016, the Mayo Clinic launched what may be the first clinical trial of senolytic therapy, studying the effect of the two drugs, called dasatinib and quercetin, on people with chronic kidney disease, which they hope to complete in 2021. Meanwhile Mayo and Scripps researchers have identified six different biochemical pathways that give rise to senescence, along with several drug candidates that target those pathways. Robbins says it's likely that different drugs will work better for different cells in the body.
Would radical life extension lead to moral deterioration, risk aversion, and an abandonment of creativity?
In Robbins' work, treating mice with senolytic drugs has extended their median lifespan—the age at which half the animals in his experiment have died—by about 30 percent, but hasn't extended the maximum lifespan. In other words, the oldest mice treated with the drugs died at the same age as mice who hadn't been treated, but more of the mice who received senolytics lived to that ripe old age. The same may turn out to be true for humans, with more people living to the limits of the lifespan—estimated by some to be about 115—but no one living much longer. On the other hand, Robbins says, it's early days for these therapies, and it may turn out that delaying aging actually does push the limit of life farther out.
Others expect more radical extensions of human life; British gerontologist Aubrey DeGray talks about people living for 1000 years, and people who call themselves transhumanists imagine replacing body parts as they wear out, or merging our minds with computers to make us essentially immortal. Brian Green, an ethicist at Santa Clara University in California, finds that concept horrifying. He fears it would make people value their own lives too highly, demoting other moral goods such as self-sacrifice or concern for the environment. "It kind of lends itself to a moral myopia," he says. "Humans work better if they have a goal beyond their own survival." And people who live for centuries might become averse to risk, because with longer lives they have more to lose if they were to accidentally die, and might be resistant to change, draining the world of creativity.
Most researchers are focused on "extending the 'healthspan,' so that the people who live into their 90s are vigorous and disease-free."
He's not too worried, though, that that's where studies such as the Mayo Clinic's are headed, and supports that sort of research. "Hopefully these things will work, and they'll help us live a little bit longer," Green says, "but the idea of radical life extension where we're going to live indefinitely longer, I think that is very unrealistic."
Most of the researchers working on combatting aging don't, in fact, talk of unlimited lifespans. Rather, they talk about extending the "healthspan," so that the people who live into their 90s are vigorous and disease-free up until nearly the end of their lives.
If scientists can lengthen life while reducing the number of years people suffer with dementia or infirmity, that could be beneficial, says Stephen Post, a professor of medicine and director of the Center for Medical Humanities, Compassionate Care, and Bioethics at Stony Brook University in New York. But even increasing the population of vigorous 90-somethings might have negative implications for society. "What would we do with all these people who are living so long?" he asks. "Would we stop having children? Would we never retire?"
Adding 2.2 healthy years to the U.S. life by delaying aging could benefit the economy by $7.1 trillion over 50 years.
If people keep working well past their 60s, that could mean there would be fewer jobs available for younger people, says Maxwell Mehlman, professor of bioethics at Case Western Reserve University's School of Law in Ohio. Mehlman says society may have to rethink age discrimination laws, which bar firing or refusing to hire people over a certain age, to make room for younger workers. On the other hand, those who choose to retire and live another two or three decades could strain pension and entitlement systems.
But a longer healthspan could reduce costs in the healthcare system, which now are driven disproportionately by older people. Jay Olshansky, an epidemiologist at the University of Illinois at Chicago School of Public Health, has estimated that adding 2.2 healthy years to the U.S. life by delaying aging would benefit the economy by $7.1 trillion over 50 years, as spending on illnesses such as cancer and heart disease drop.
For his part, Robbins says that the scientific conferences in the anti-aging field, which tend to focus on the technical research, should hold more sessions on social and economic impacts. If anti-aging therapies start extending healthy lifespans, as he and other researchers hope they will within a decade or so, society will need to adjust.
Ultimately, it's an extension of health, not just of longevity, that will benefit us. Extra decades of senescence do nobody any good. As Green says, "Nobody wants to live in a nursing home for 1000 years."