Autism spectrum disorders (ASD) are conditions that affect development. They impact the ways a person interacts with other people and alter how they perceive the world.
And, though every case is different, the most common symptoms include delayed speech development, trouble interacting with peers, and repetitive behaviors.
As for prevalence, in 2016, the Centers for Disease Control and Prevention (CDC) estimated that it affected 1 in 68 children — about 1.5 percent of all children. However, this week, they updated this estimate.
The revision comes off the back of the CDC's Autism and Developmental Disabilities Monitoring (ADDM) Network. This tracking system follows more than 325,000 8-year-old children, which accounts for around 8 percent of all 8-year-olds in the United States.
The ADDM assesses the young participants for any characteristics of ASD. It is the largest network of its type and the only one that also follows the health and education of each child.
The data come from 11 communities in Arizona, Arkansas, Colorado, Georgia, Maryland, Minnesota, Missouri, New Jersey, North Carolina, Tennessee, and Wisconsin. The new results were published earlier this week.
According to the analysis, in 2014, 1 in 59 children — or 1.7 percent — had ASD. That represents a 15 percent rise from 2 years ago. Also, boys were four times more likely to receive a diagnosis than girls.
Why has the figure changed?
There are many potential ways to explain why the percentage of children with ASD may have risen. For instance, improvements in the identification of ASD in minority populations could be part of the answer.
Although, ASD is still more likely to be diagnosed in white children than Hispanic or black children.
Dr. Stuart Shapira, an associate director for science at CDC's National Center on Birth Defects and Developmental Disabilities, explains:
"Autism prevalence among black and Hispanic children is approaching that of white children. The higher number of black and Hispanic children now being identified with autism could be due to more effective outreach in minority communities and increased efforts to have all children screened for autism so they can get the services they need."
Improving diagnostic services in minority communities is vital; the earlier ASD is caught, the more successful interventions tend to be. If children are put in contact with support services at an early age, they are more likely to reach their full potential.
Interestingly, autism rates across the 11 communities varied. Five regions had similar levels (1.3–1.4 percent), but the highest rate was seen in the New Jersey community, which hit 1 in 34 (2.9 percent).
The researchers believe that this disparity might be due to differences in the way that autism is documented and diagnosed in different areas.
After the 2016 results were published, many concluded that the rise in ASD had paused. Now, some believe that this may not be the case.
For instance, Walter Zahorodny, who is an associate professor of pediatrics at Rutgers New Jersey Medical School in Newark — who orchestrated the New Jersey part of the investigation — says:
"It is now clear that what we saw in 2016 was just a pause along the way. It remains to be seen at what point ASD rates will plateau."
Exactly why autism rates might be rising is not entirely clear. One factor that could be involved is that, nowadays, people are having children at an older age, when maternal illnesses, genetic mutations, and multiple pregancies are more likely.
"These are true influences that are exerting an effect, but they are not enough to explain the high rate of autism prevalence," says Zahorodny.
"There are still undefined environmental risks which contribute to this significant increase, factors that could affect a child in its development in utero or related to birth complications or to the newborn period. We need more research into non-genetic triggers for autism."
Early diagnosis is key
The take-home message from these findings is that diagnosis needs to occur earlier. For instance, they found that fewer than half of children who identified as having ASD received their diagnosis before they were 4.
Also, although 85 percent of children with ASD had medical notes outlining concerns about their development by the age of 3, only 42 percent of them had received a developmental evaluation.
"Parents can track their child's development and act early if there is a concern," explains Dr. Shapira. "Healthcare providers can acknowledge and help parents act on those concerns."
"And those who work with or on behalf of children can join forces to ensure that all children with autism get identified and connected to the services they need as early as possible," he adds. "Together, we can improve a child's future."
The ADDM's next report will provide data from children who were 8 in 2016. Once this information is added, it will make it easier to see whether autism rates are increasing, or whether there has been a change in identification rates.