Symptoms of autism spectrum disorder (ASD) often appear during the first two years of life, according to the National Institute of Mental Health (NIMH).

ASD can occur in all ethnic, racial, and economic groups. However, according to the Centers for Disease Control and Prevention (CDC), it’s diagnosed about four times as frequently among boys than among girls in the United States.

The CDC also reports that over 5.4 million adults in the U.S. were living with ASD as of 2017, representing about 2.2 percent of the population.

Prevalence Of Autism Spectrum Disorder (ASD)

The Autism and Developmental Disabilities Monitoring (ADDM) Network first began monitoring children diagnosed with ASD in the year 2000, discovering a prevalence of about one in 150 children that year.

By 2016, the rate of ASD was 18.5 per 1,000. This means that about one in 54 children living in the 11 states monitored by the network were diagnosed with ASD. However, it’s important to note that the overall prevalence may differ across the U.S. as a whole.

ASD In Men And Women

For every girl who is diagnosed with ASD, between three and four boys are diagnosed.

A 2017 clinical review of 54 studies of ASD published in the American Academy of Child and Adolescent Psychiatry found there was significant variation between the number of female vs. males diagnosed with ASD.

The extensive 2017 review reported it’s possible that some girls may be at risk of being misdiagnosed or not diagnosed with ASD. The authors suggest this may be due to clinical bias and potential beliefs that males experience ASD at a greater rate than females.

ASD In Specific Populations

Data from the ADDM Network shows that in 2016 there were no significant differences in the prevalence of ASD among non-Hispanic white (18.5 per 1,000) and non-Hispanic black children (18.3 per 1,000).

However, Hispanic children had a lower rate of ASD diagnosis at 15.4 per 1,000, as did Asian and Pacific Islander children at 17.9 per 1,000.

The CDC reports that a diagnosis of ASD is 1.1 times more likely to be made among white vs. black children, and 1.2 times more likely to be made among white vs. Hispanic children.

It’s unlikely that there are real differences in the rate of ASD between different ethnic and racial groups. Instead, the CDC suggests there are disparities in how children are identified, diagnosed, and treated.

ASD And The Rate Of Co-occurring Conditions

When the intellectual abilities of children with ASD are analyzed, about 33 percent are classified as having intellectual disabilities, or an IQ of less than 70.

According to the Autism Treatment Network and CDC data, more than half of children with ASD have been diagnosed with a gastrointestinal disorder, and up to 16 percent have a seizure disorder.

As many as 78 percent of children with ASD can have a sleep disorder, and up to three-quarters of children with ASD can have depression, anxiety, ADHD, or other behavioral issues. Allergies and asthma are additional co-occurring conditions experienced by people with ASD.

Global Impact Of Autism Spectrum Disorder

The World Health Organization (WHO) reports that one in 160 children around the world have an autism spectrum disorder.

The prevalence of ASD is increasing around the globe. Because some low- and moderate-income countries have not been tracking ASD diagnoses, the full prevalence is not understood. However, WHO estimates that between one percent and two percent of people have ASD worldwide.

Autism Spectrum Disorder: Treatment Facts

According to MassGeneral for Children, the earlier a child is diagnosed with ASD and the earlier they can receive interventions, the greater the likelihood of positive treatment outcomes.

Because it’s such an individualized and diverse condition, there is no specific treatment for ASD. However, behavioral interventions, assistance with language development and use, and help to develop and use social skills can assist people with ASD.

Although ASD cannot be cured, people who receive help and interventions continue to grow, change, and better manage their condition throughout their lives.