A new survey has revealed that prevalence of autism spectrum disorders among children and teenagers aged 3 to 17 years old in the United States has reached a plateau after 20 years of steadily increasing.

The evidence was gathered through the National Health Interview Survey, an annual census that involves personal interviews. If a participating household includes children, a child is selected in random and an adult is asked for information about such child's medical background.

Previous versions of the census followed a standard set of questions until a new one was added in 2014.

"Has a doctor or health professional ever told you that the child had autism, Asperger's disorder, pervasive developmental disorder, or autism spectrum disorder?" it states.

ASD Is More Prevalent Among White American Children And Teens

The study shows that out of the 305,502 participating families, more than 700 have answered yes to the question. Specifically, 711 children and teenagers have been reported in to be struggling with ASD in 2016. The number also puts the prevalence of ASD among such population at a rate of 2.41 percent, with no significant increase recorded over the past three years.

An increase over the past 20 years was credited by the study to changes in public awareness, diagnostic criteria, genetics, and environmental risk factors. However, such conclusion is only a theory and will need further investigation to be proven as correct.

Moreover, the study also explored the prevalence of ASD according to gender and ethnicity. Prevalence was recorded at 3.54 percent in boys, 1.22 percent in girls, 1.78 percent in Hispanic children and teenagers, 2.71 percent in non-Hispanic White children and teenagers, and 2.36 percent in non-Hispanic Black children and teenagers.

This is not the first that prevalence of ASD has recorded higher in non-Hispanic White children. A separate study conducted in 2012 has yielded similar results, with prevalence among non-Hispanic White children estimated at 15.5 per 1,000 8-year-olds, non-Hispanic Black children at 13.2 per 1,000, and Hispanic children at 10.1 per 1,000.

Research Explores Early Identification Of Autism

While there is currently no cure available for ASD, scientists have studied different methods to detect it during a child's early years. One study, in particular, found that the volume of cerebrospinal fluid in an infant's subarachnoid space serves as an indicator of the disability.

By monitoring more than 300 infants, researchers confirmed that 6-month-old babies with an increased CSF in their extra-axial area are later diagnosed with ASD as they turn two years of age.

The study was funded by Autism Speaks, an American organization advocating the awareness and study of ASD.

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