Autism statistics can vary substantially. That’s partly because of differences in the way autism, now called autism spectrum disorder, is studied, reported and diagnosed. And it’s also because we are still learning about the condition characterized by repetitive or restricted activities as well as difficulties communicating, learning, problem solving or interacting with others.
But one thing is clear: “Autism is reported to be present across socioeconomic, cultural, racial and ethnic groups,” says clinical psychologist Allison Wainer, research director at Rush University Medical Center’s Autism Assessment, Research, Treatment and Services Center.
- A March 2020 report from the Centers for Disease Control and Prevention that evaluated medical information from patients throughout the U.S. Researchers found that 1 in 54 children age 8 had ASD.
- In a 2018 study in Pediatrics that evaluated 43,000 parent-reported survey responses, researchers found that 1 in 40 kids between ages 3 to 17 had ASD.
Both of the those autism statistics are higher than the amount of ASD cases estimated worldwide, which is 1 in 160 children, according to the World Health Organization.
Why is there a significant difference in the figures? WHO notes that its estimate is an average of global numbers, affected by some low-income countries where ASD prevalence is unknown.
Varying assessment methods also affect autism statistics. “In areas that have less well-developed research and clinical infrastructures, prevalence is often calculated through medical record review. The rate of autism diagnosis in these medical records might be lower because clinicians are not well versed in identifying and diagnosing autism or there might be cultural stigma related to making the diagnosis,” Wainer explains.
A Rising Trend
U.S. autism statistics have shown an upward trend for the last two decades. While the CDC estimate of children with ASD is 1 in 54 today, previous CDC estimates were:
- 1 in 150 in 2002.
- 1 in 125 in 2004.
- 1 in 110 in 2006.
- 1 in 88 in 2008.
- 1 in 68 in 2010.
- 1 in 59 in 2014.
The increasing prevalence of ASD may be due in part to better detection. “We’ve changed the criteria for diagnosis, so more people fit on the spectrum of autism than they did 25 years ago,” says Dr. Daniel Coury, a developmental-behavioral pediatrician at Nationwide Children’s Hospital and medical director of the Autism Speaks Autism Treatment Network.
Wainer agrees. “We are getting better at identifying autism in a range of behavioral profiles, from profound intellectual disability to high intellectual ability and everyone in between,” she says. “And there are more physicians and mental health providers who are trained in identifying autism, so there’s a larger workforce able to identify and diagnose the condition.”
But better detection may not explain the entire story. “It accounts for most of the increases we’ve seen, but not all of them,” Coury says. “There is still concern that something else is going on to increase the cases. But we aren’t able to explain it.”
Male vs. Female Autism
- 1 in 34 boys.
- 1 in 144 girls.
It’s not clear why ASD is diagnosed less frequently in girls than boys. It could be that ASD symptoms are less noticeable in girls. “Girls may present differently, maybe as shy or anxious compared to male counterparts who tend to be more disruptive. Girls with autism also show fewer restricted interests, repetitive behaviors and aggression or conduct problems than boys,” says clinical psychologist Jean Gehricke, associate research director at the Center for Autism and Neurodevelopmental Disorders at the University of California—Irvine.
Another theory is that girls have an underlying genetic mechanism that keeps them from developing ASD less often than boys. “Recent evidence suggests that girls may need a higher genetic load to develop autism. It may be a female protective effect,” Gehricke says.
When it comes to autism statistics on co-existing ASD conditions, the advocacy group Autism Speaks points out that among the child or adult ASD population:
And there are other potential co-existing conditions in ASD, such as:
- A low IQ.
- Cerebral palsy.
- Gastrointestinal problems such as constipation.
- Hearing loss.
- Learning disability.
- Mental health disorders such as obsessive compulsive disorder, schizophrenia or bipolar disorder.
- Stuttering or stammering.
Having any one of these conditions is difficult on its own. But in ASD, the effect is compounded. “If you have blindness or hearing loss, that makes the problem of communicating even harder,” Coury says. “Similarly, if you have a low IQ, you have difficulty understanding general language. And in autism, you have problems with communication, so now you have an even greater difficulty understanding the world around you and what people are talking about.”
ASD also makes it hard to express that you’re having particular symptoms of another condition. “It’s hard to share that you’re constipated or your stomach hurts or you’re uncomfortable or having headaches or dental problems. You can’t share what’s hurting,” Wainer says.
Coping With Risks
You don’t need to memorize autism statistics in order to cope with the condition or help care for someone who has ASD. But experts say that understanding the likelihood of developing particular health problems enables you to be proactive about treatment and help someone with ASD get regular physical and dental exams to stay ahead of potential problems.
Experts also recommend making sure that people with ASD always have a way to communicate about ailments. “Make sure everyone has a way to let us know when they need or want something. That might mean having a way to communicate with pictures or other kinds of assistive devices,” Wainer says.
And when there is an additional health problem in someone with ASD, seeking treatment becomes crucial. “In general, more co-existing problems lead to more complex developmental and health problems, which require more complex behavioral and medical interventions,” Gehricke says. “Treatment of these other conditions can significantly improve quality of life in individuals with ASD.”