Doctors have revealed the myriad causes of autism spectrum disorder, as diagnoses of the condition increase in the US.
Recent figures suggest that rates in children and adults have tripled in the last decade.
A study in JAMA Network Open found that autism diagnoses among all age groups increased 175 percent between 2011 and 2022, from a rate of 2.3 to 6.3 per 1,000 people.
And the biggest increase was among young adults ages 26 to 34, with a 450 percent increase.
A large body of research indicates that doctors are getting better at diagnosing the condition due to increased detection and broader diagnostic criteria.
But increasingly, other factors are being considered behind the increase, including environmental factors such as increased exposure to pollution and pesticides.
Dr. Cooper Stone, a Philadelphia psychiatrist, told DailyMail.com that exposure to toxic metals, pesticides and pollution could also play a role in the increase.
He said: “There is a strong belief that environmental factors may be partly involved in the development of this condition. While no direct environmental causes have been linked to ASD, there are many associated risk factors that appear to have a relationship.
Experts told DailyMail.com that autism rates could be rising due to increased screening, broader definitions and environmental exposures.
According to the CDC, about one in 36 American children and one in 50 adults have autism.
Generally, most sufferers of this disorder are diagnosed at age five, although some can be tested as young as two years old.
Children aged five to eight remained the group most likely to be diagnosed, with a rate of 30 per 1,000.
The condition is marked by repetitive behaviors, interests, and activities; deficits in social communication and social interaction; and the presence of high or low sensory sensitivity.
There is no cure, but doctors can provide therapies to help with symptoms.
TO review published last year It found that people with a genetic predisposition to autism, such as a parent with the condition, who were exposed to pollution early in life were more likely to develop autism than those exposed to less pollution.
Previous Harvard research also found that exposure to air pollution, such as particulate matter, in early childhood can increase the risk of ASD by up to 64 percent.
While in the womb, exposure to particles can increase the risk of ASD by 31 percent.
An Australian study published earlier this year also found that children exposed to the endocrine-disrupting chemical bisphenol A (BPA) in utero were six times more likely to be diagnosed with autism before age 11 than those without exposure.
That team suggested that BPA, which coats plastic and metal food packaging, was associated with neurological and behavioral changes associated with autism.
The United States has also seen an increase in the use of synthetic pesticides, which they say could also contribute.
The use of these chemicals has increased 50-fold since 1950.
In 1952, for example, only one in 10 corn fields used pesticides to help kill pests. But in 1982, 95 percent of corn fields were using them.
Some research indicates that up to 80 percent of Americans have detectable levels of pesticides in their blood.
The graph above shows increases in autism diagnoses from 2011 to 2022 by age group, according to research published earlier this year in JAMA Network Open.
The graph above shows the gap in autism diagnoses between men and women, suggesting that diagnoses in women are catching up with those in men.
Earlier this year, the EPA announced an emergency suspension of the pesticide dimethyl tetrachloroterephthalate (DCPA or Dacthal) due to evidence suggesting that babies exposed to it in utero could be born with low weight and poor IQ and developmental reduced.
TO recent study It also suggested that unborn babies exposed to traffic-related air pollution were more likely to be diagnosed with autism.
Furthermore, a review 2021 found that “the odds of an autism diagnosis were 3.3 times higher in people born prematurely than in the general population,” as premature babies are vulnerable to birth complications and inflammation associated with autism.
This means the rise in autism could be due to more premature babies surviving birth, as the survival rate has increased from 76 percent between 2008 and 2012 to 78 percent between 2013 and 2018, according to National Institutes of Health research (NIH).
About one in 10 babies in the U.S. are born premature, according to the CDC, meaning they are born before 37 weeks of gestation.
Some experts also believe the increase is because doctors have become better at recognizing and diagnosing the condition.
This also means that older people with autism may have never been properly evaluated and are just receiving their diagnosis.
In 2013, officials at the American Psychiatric Association updated the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), which is used to diagnose mental conditions such as anxiety, depression, and bipolar disorder.
The changes collapsed autism, Asperger syndrome AND pervasive developmental disorder into one category, autism spectrum disorder.
This may have led to more children being considered autistic.
Dr. Courtney Scott, medical director of Transcendent Recovery Grouptold DailyMail.com: ‘The introduction of new diagnostic criteria by the DSM-5 has resulted in a considerably wider range of presentations and behaviors that clinicians associate with autism spectrum disorder (ASD).
“This strategy is beneficial because it also includes milder or less typical symptoms of ASD, so that more people with this disorder who were previously undetected can receive comprehensive support resources.
“This increase in the number of diagnoses could also be explained to some extent by this expanded point of view.”
Dr. Stone said social media sites like TikTok have brought more attention to the condition, especially in groups less likely to be diagnosed, such as adults and girls, who share symptoms they had overlooked.
He said: “Although in many cases social media can be a big provider of misinformation on the topic, it still results in more people seeking diagnostic evaluation, and a portion of those people receiving a diagnosis.”
Last year, researchers at the University of South Carolina analyzed data from 700,000 children to map the counties where autism is most common.
Using this data, they found hot spots in the Southeast, East Coast, and Northeast. Rates were specifically high in New Jersey, ranging from 2.6 to 8.1 percent of the total child population.
Meanwhile, rates were especially low in the Texas Panhandle and Oklahoma.
Experts suggested these areas could have a higher rate of diagnoses due to pollution from urban populations and greater access to therapists and screening programs.
While none of this research has found a definitive cause, Dr. Scott said it could help detect the condition earlier and prevent it.
He said: “Although the causes have not been identified so far, the results (of the study) are helping to unravel the riddle of ASD and, in the long term, helping to formulate better ways to prevent and treat the condition.”