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Autism rates may have been underestimated in the United Stated, experts at the Centers for Disease Control and Prevention are now warning.
Apparently, this neurodevelopmental disorder used to affect 1 in 68 children, as evidenced by National Health Interview Surveys (NHIS) conducted between 2011 and 2013. Now, the condition can be encountered among 1 in 45 children, according to the 2014 survey, which included over 10,000 parents.
In other words, the prevalence of autism among kids aged 3 to 17 has increased by 80%, from 1.25% to 2.24%. The numbers are staggering, given that decades ago it was estimated that just around 4 to 5 children out of 10,000 have been diagnosed with autism spectrum disorder (ASD).
ASD manifests itself through repetitive, limited behavior, as well as difficulty when it comes to social interaction and communication, up to 40% of the patients never developing the ability to speak.
Children who have this condition have trouble maintaining eye contact or employing other types of nonverbal communication, and frequently fail to grasp the feelings of the ones around them.
They are also more prone to stereotypical actions such as body rocking or head banging, and tend to develop excessive preoccupation towards certain topics or objects.
Researchers are now speculating what might have caused the incidence of this condition to spike so obviously. Some believe this may be linked to the MMR (measles, mumps, rubella) vaccine, but this hypothesis has been contradicted by several extensive studies.
Others allege that influenza infections suffered by women during pregnancy might be to blame, while some others claim the culprit is represented by exposure of the fetus to air pollution and other environmental factors.
However, experts at the Centers for Disease Control and Prevention are of the opinion that the questions included in the survey might actually account for the disparity between the two separate findings.
Apparently, both surveys initially asked about potential intellectual disabilities, but while the 2011-2013 survey then went on by inquiring about developmental delays and specific disorders such as ASD, the more recent survey switched the order of the questions, focusing on ASD specifically and only afterwards on other impairments.
Therefore, it may be that this time parents simply associated their children’s condition more easily with ASD instead of labeling it as a developmental disability. This idea is supported by the fact that the prevalence of other similar disorders seems to have decreased from 4.84% to 3.57%.
According to Paul Lipkin, director of the Kennedy Krieger Institute’s Interactive Autism Network, it may also be that diagnostic rates for autism have improved, due to heightened awareness among physicians and families, when it comes to the condition’s most common signs and symptoms.
In fact, these findings are similar to the ones collected by the National Survey of Children’s Health (NSCH), which estimated that autism affects around 1 in 50 kids.
Another interesting trend revealed by this new research is that the gender gap concerning autism is getting smaller. Previously, it had been thought that autism prevalence is 4 to 5 times higher among boys, whereas nowadays the condition is just around 3 times more common than among girls (3.29% versus 1.15%).
Also, autism rates are similar in different age groups: 2.34% for kids aged 3 to 10, and 2.13% for those aged 11 to 17. As far as racial distribution is concerned, incidence is highest among Caucasians (2.55%), and lowest among Hispanic children (1.49%), while the percentage of African-American kids with this condition is of 2.21%.
It must be noted that uninsured families are less likely to report the presence of this disorder, but may be simply because of diminished access to healthcare, allowing them to obtain an accurate diagnosis.
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