By Matt Schur from the AMT Pulse.
By the end of the 20th century, autism was emerging into public view faster than medicine could explain it.
Cases were on the rise. The condition’s concept was shifting. And people were rightfully worried.
“I don’t necessarily want to say that people were desperate,” says A.J. Russo, PhD, Research Director, Mensah Medical. “But it was really important, especially for parents, to try and find an answer.”
Then, in 1998, British gastroenterologist Andrew Wakefield, working as the lead author, published research in The Lancet claiming a connection between the measles-mumps-rubella (MMR) vaccine and autism. Wakefield suggested that the shot triggered autism by causing intestinal inflammation that ultimately affected the brain.
The study catapulted the connection between vaccines and autism into a global dialogue, says David Mandell, Sc.D., Professor and Director, Penn Center for Mental Health. Dr. Mandell has studied autism for more than two decades, publishing research on its causes, prevalence and how to improve care. “The kindling was there. But Wakefield set the fire.”
Researchers in Denmark have published two separate epidemiological studies after Wakefield’s paper that demonstrated no link between vaccines and autism, the first involving 537,303 children and the second involving 657,461 children. Wakefield’s study involved 12 children.
Sample size proved to be just one of the many red flags with Wakefield’s research, including:
- Wakefield’s study didn’t have a control group.
- Prior to publication, Wakefield failed to mention that several of the families involved in the study were suing vaccine manufacturers, creating an incentive for the families to prove a connection between vaccines and autism.
- Lawyers for those litigating families paid Wakefield more than $500,000 to research a connection between vaccines and autism.
- Wakefield had filed a patent for a competing vaccine.
“He was going to be able to use this theory to bring down MMR vaccines, and, on the side, make a fortune with his own patent,” says Helen Tager-Flusberg, PhD, the Director for the Center for Autism Research Excellence and a Professor Emerita at Boston University.
Wakefield later admitted that he also fabricated elements of his research. The Lancet eventually retracted the paper, and Britain’s General Medical Council stripped Wakefield of his medical license.
But Wakefield’s ideas had already taken hold, and concerns over vaccines went global, ith major drops in vaccination confidence and rates. For instance, before the paper, measles vaccination rates in Great Britain were around the herd immunity threshold of 95%. By 2003-2004, vaccination rates fell to 80%, and measles was declared an epidemic in England and Wales.
These challenges continue today. There were nearly 2,000 cases of measles in the United States in 2025, an increase of more than 14,000% since 2020. In just January of this year, there were roughly 600 measles cases.
The Origins of Understanding Autism
The root of the word autism comes from the Greek word “autos,” meaning self. “The idea is that you are withdrawn into yourself,” Dr. Mandell says. “This lack of social connection, whether because of ability or willingness to relate to other human beings, feels like the antithesis of what it means to be human, which can be scary, especially for parents.”
Today, researchers know that autism spectrum disorder is a complex neurodevelopmental condition that begins during early fetal development and affects roughly 1 in 31 kids, according to the U.S. Centers for Disease Control and Prevention. As Dr. Mandell alludes to, autism shows up most apparently as a social disorder, affecting communication and social skills, and causes restrictive or repetitive behaviors.
But there wasn’t much known about autism for most of the 20th century. “When I started conducting research in the 1970s, no one knew what autism was, including many clinicians,” says Dr. Tager-Flusberg.
At that time, autism was being attributed to emotionally cold mothers. Research picked up steam in the late 1970s when Michael Rutter and Susan Folstein conducted studies that suggested autism was far more common among identical twins than fraternal ones, suggesting a genetic component to the condition.
But without sophisticated genetic tools, the science remained incomplete. Plus, as Dr. Tager-Flusberg says, “At the beginning, we only saw the most severe kinds of social impairment, children who were completely withdrawn and didn’t connect to others.”
As research efforts grew, autism became more visible. In 1990, autism was added as a standalone category under the Individuals with Disabilities Education Act. As part of that, for the first time, the U.S. started to systemically count the number of autistic children in the country. In 1994, the DSM-IV expanded the definition of autism to go beyond just extreme cases to include a broader range of individuals, which is now considered the spectrum of autism.
The increased awareness, the act of counting, the expanded definition—all major developments that started laying the groundwork to improve outcomes for people with autism. “But it’s also creating a lot of anxiety,” Dr. Mandell says.
Environment Before Wakefield’s Paper
Autism symptoms often become noticeable in the second year of life, around the same period children receive the MMR vaccine. To anxious parents, the overlap felt like causation.
“Wakefield’s paper became very powerful,” Dr. Russo says. “I think that parents particularly latched onto it and began to question whether there was a connection.”
Dr. Mandell’s daughters were born around this time and were getting vaccinated in the early 2000s. Because of Wakefield’s paper, “I remember, along with other parents of young children, being really, really scared of the potential for vaccines to cause neurodevelopmental damage,” Dr. Mandell says. “People took his findings very seriously.”
Dr. Mandell was not just a trained researcher, but someone who had been specifically studying autism. What were the rest of the parents to think?
Shifting Goalposts
Numerous studies and meta-analyses involving millions of children across multiple countries and healthcare systems have repeatedly found no connection between the MMR vaccine and autism. That includes a 2012 Cochrane Library report involving data from 14.7 million children and a 2014 meta-analysis in the medical journal Vaccinethat involved 1.2 million children across five cohort studies.
In the wake of the evidence, many vaccine skeptics pivoted away from the MMR connection and began focusing on thimerosal, a mercury-containing preservative used in some vaccines. Despite a lack of evidence showing a connection between thimerosal and autism, in an abundance of caution, thimerosal was removed or drastically reduced in nearly all childhood vaccines in the early 2000s. If thimerosal were the cause, autism rates should have declined. Instead, diagnoses continued to increase.
From there, the argument broadened. If no single vaccine ingredient could be blamed, perhaps children were receiving too many vaccines, too close together, overwhelming their immune systems and triggering autism. Other theories have and continue to spring up: aluminum adjuvants and Tylenol and more.
“It’s a game of whack-a-mole,” says Peter J. Hotez, MD, PhD, Dean, National School of Tropical Medicine, Baylor. He is also the author of multiple books on the anti-science movement. “Every time science debunks one claim, another takes its place.”
Sound Science
Deciphering what is and isn’t true might be more difficult now than at any previous time in human history. For that reason, in healthcare, workers need to be educated about these studies and data so they can be prepared to answer patient questions.
And it’s true that researchers still don’t know everything about autism. For instance, as with depression or anxiety, there isn’t a biological marker to determine if someone has autism. Diagnoses rely on specialist assessments using a wide range of reports, observations and tools.
But a lot is known, including that autism begins during pregnancy. One well-established example is that exposure to valproic acid, an anti-seizure medication, during early pregnancy significantly increases the risk of autism. “We also know that infants in the first year of life are showing differences in brain structure and function,” Dr. Tager-Flusberg says. “That’s why research is looking at prenatal environmental contributions to autism and how they might interact with predisposing genetics.”
The million-dollar question remains why autism numbers are increasing. Researchers point to the same conditions that existed in the early 1990s: classifications continuing to broaden and increased attention on the condition. “There’s so much of an emphasis now on parents viewing the behavior of children, looking carefully at their behavior,” Dr. Russo says. “I think that, most importantly, we’re diagnosing autism much more frequently now than we did decades ago.”
There are other factors contributing to the increased number of diagnoses, too, including insurance coverage and access to services. In many states and insurance plans, for instance, an autism diagnosis unlocks access to behavioral therapies that are otherwise difficult or impossible to obtain.
Behavioral therapies that are now routinely covered for autism are often just as beneficial for children with other neurodevelopmental conditions, including intellectual disability, language disorders and certain genetic syndromes. Yet those diagnoses do not always come with the same insurance protections, Dr. Tager-Flusberg says. As a result, clinicians and families face a practical dilemma: without an autism diagnosis, services may be delayed, denied or financially out of reach. “Kids with intellectual disability or other neurodevelopmental disorders benefit from the same behavioral therapies,” Dr. Tager-Flusberg explains. “But autism is what insurance covers.”
While clinicians are not fabricating autism diagnoses, Dr. Tager-Flusberg says, they are operating in a system that rewards one label over others. When a child meets partial criteria for autism and also has significant developmental needs, there is often pressure—implicit or explicit—to diagnose autism to secure services, she says. Over time, that pressure contributes to broader diagnostic boundaries and rising prevalence figures, reinforcing the public perception that autism itself is becoming more common, even when the underlying population of neurodevelopmental differences may not be changing at the same rate.
Shifting the Focus
Healthcare workers, especially those on the front lines, are often the most trusted sources of information patients encounter. One thing to remember: Parents and patients may arrive at appointments anxious, skeptical or misinformed, but they are also seeking reassurance.
Countering their fear requires patience, the willingness to speak plainly about what is and isn’t known, and granting some grace. After all, parents typically just want what’s best for their kids.
Listening is one of the first, most important steps. “Each person’s vaccine hesitancy may come from a different source or reason,” Dr. Tager-Flusberg says. “And nobody wants to be bombarded the minute they say they aren’t sure about vaccines. I think it’s really important to start with questions about why they think and feel the way they do, and then you can provide appropriate information.”
Such efforts from healthcare workers can help counter the stigma that has cropped up around autism. Dr. Hotez, whose daughter Rachel is autistic, has been especially vocal about the damage this framing causes. When autism is discussed only as something to be feared or prevented, it dehumanizes the millions of people living full, meaningful lives on the spectrum. Rachel works, pays taxes, has friends and leads a life she enjoys, Dr. Hotez says. “That’s the part that feels eugenics-adjacent,” Dr. Hotez says. “When people say autistic people don’t contribute to society, they’re just wrong.”
As Dr. Mandell adds, part of the fear campaign is that autistic people will never enjoy familiar life activities, like playing baseball or writing poetry. “But, for instance, there’s an autistic adult I know who sends me his poetry every month,” he says.
One difficult aspect for many researchers is that the antivaccine movement is diverting attention and funding away from critical projects that could improve outcomes. Early intervention, improvements in school-based services, better support for autistic adults and coordinated care models all show great promise, Dr. Mandell says. But they require sustained investment.
“As healthcare workers, we need to do a much better job of telling the complete story and helping people make decisions that are based on scientific information,” Dr. Russo says.