An estimated 1 in 45 adults in the United States have autism, indicating a critical need for diagnostic tools and services for adults.

Background: ASD is a developmental disability characterized by social communication challenges and restricted and repetitive behaviors, for which some people may require extensive support across the lifespan. Children diagnosed with ASD may receive school-based supports and services, enabling surveillance for the prevalence, characteristics, and needs of children with ASD. But as children with ASD transition into adulthood, they also transition out of these supports and services. As a result, less is known about the prevalence, characteristics, and needs of adults with ASD. It is critically important to understand national and state-based estimates of adults with ASD to inform development of programs, policies, and services to support them.

Methods & Findings: This study used 2017 data from the National Survey of Children’s Health (NSCH) and population mortality rates to estimate the prevalence of ASD in adults. The researchers estimated that there was approximately 2.21% of adults with ASD in the United States in 2017. State prevalence of ASD in adults ranged from 1.97% in Louisiana to 2.42% in Massachusetts. California, Texas, and New York had the greatest estimated number of adults with ASD. There was no obvious geographical pattern for estimated prevalence across the states. The national prevalence of ASD was 0.86% in adult women and 3.62% in adult men.

Implications: There is currently no standardized, validated assessment for ASD in adults. Additionally, some adults with ASD may live independently and not receive services, creating a challenge in accurately determining ASD prevalence in adults. This study estimated that 1 in 45 adults in the United States live with ASD, which indicates a critical need to develop validated ASD assessment tools and provide evidence-based services specific to adults.

Autistic adults older than 65 years have higher rates of nearly all health conditions that typically affect older adults, indicating a need for more supports and services.

Background: Across the general population, older adults (over age 65) have specific health care needs, with differences in the likelihood of co-existing physical and mental health conditions as compared to younger adults. Research has indicated that prevalence of co-existing conditions may further differ among autistic older adults. It is therefore important to determine the prevalence of physical and mental co-existing conditions in autistic older adults to inform the development of the specific services and supports needed to maintain wellbeing.

Methods & Findings: Using a national sample of Medicare beneficiaries between 2016 and 2017, the researchers of this study aimed to compare the prevalence of physical and mental co-existing conditions among older autistic adults and older non-autistic adults. They identified 4,685 autistic older adults and generated a randomized comparison sample of 46,850 non-autistic older adults. Over 43% of autistic individuals had co-existing intellectual disability as compared to 0.2% of the comparison sample. Autistic older adults were significantly more likely to have co-existing physical health conditions such as osteoporosis, cognitive/neurological disorders, heart disease, cancer, cerebrovascular disease, and osteoarthritis. Autistic older adults were also significantly more likely to have co-existing mental health conditions, with the most significant likelihood for schizophrenia/psychotic disorders, attention deficit disorders, and personality disorders. Notably, autistic older adults were 11 times more likely to have sought care for suicidality or intentional self-injury.

Implications: This study provides new and valuable insights into health care needs of autistic older adults. The results of this study indicate that autistic older adults are significantly more likely to have a co-existing physical or mental health condition than non-autistic older adults. These findings highlight a critical need to address the conditions of this older autistic population in health care policies, programs, and services.

CDC data from 2016 estimates that 1 in 54 eight-year-old children are diagnosed with autism.

Background: The Centers for Disease Control and Prevention (CDC) established the Autism and Developmental Disabilities Monitoring (ADDM) Network to report the prevalence of ASD in multiple communities in the United States. ADDM has captured ASD prevalence among eight-year-old children for even-numbered years since 2000. ADDM data indicate that disparities in ASD prevalence across race/ethnicity have decreased in recent years. These data suggest that there has been progress in the detection of ASD among all children.

Methods & Findings: This study reports on the 2016 prevalence of ASD in children born in 2008, as well as demographic characteristics and prevalence of co-existing intellectual disability (ID). Across all 11 ADDM sites, the prevalence of ASD was 1 in 54 eight-year-old children. ASD was 4.3 times more prevalent in boys than girls. ASD prevalence was similar among non-Hispanic White, non-Hispanic Black, and Asian/Pacific Islander children. ASD prevalence was lower among Hispanic children compared to White and Black children. Data showed that 40% of girls with ASD and 32% of boys with ASD had co-existing ID. Co-existing ID was more prevalent among Black children (47%) and Hispanic children (36%) than White children (27%). Although Black children were more likely than White children to have co-existing ID, they were less likely to be evaluated by 36 months of age than White children. Children with co-existing ID were diagnosed with ASD an average of six months later than children without co-existing ID.

Implications: The ASD prevalence in 2016 was approximately 10% higher than in 2014 and approximately 176% higher than 2000 to 2002. This increase could reflect differences ASD screening and diagnosis and/or differences in data availability. Differences in prevalence across states may indicate a need to improve ASD screening and diagnosis in certain communities. Previous ADDM analyses have found that ASD prevalence is positively correlated with socioeconomic status, suggesting that improved screening and diagnosis may be most impactful in lower socioeconomic communities. Although this study found no disparity in ASD prevalence between Black and White children, it did find racial disparities in age of ASD diagnosis, indicating a need to further understand the barriers to timely, accurate diagnosis.

CDC data from 2016 estimates that 1 in 64 four-year-old children are diagnosed with autism, showing improvements in early identification and evaluation for autism.

Background: : The Early Autism and Developmental Monitoring (Early ADDM) Network is a subset of the ADDM Network that estimates ASD prevalence and monitors early ASD diagnoses among four-year-old children. Similar to increased ASD prevalence in eight-year-old children over time, Early ADDM data has shown an increase in ASD prevalence among four-year-old children.

Methods & Findings: This study reports on the 2016 prevalence of ASD among children born in 2012 using the same data collection methods as the ADDM Network across 6 of the 11 ADDM sites. Across all Early ADDM sites, the prevalence of ASD was 1 in 64 four-year-old children. ASD prevalence was 3.5 times higher among four-year-old boys than among four-year-old girls. ASD prevalence was similar among White and Black children. At sites with available information about intellectual disability (ID), 53% of children with ASD had co-existing ID. There was no difference in co-existing ID among four-year-old boys and girls. Approximately 84% of four-year-old children with ASD had their first evaluation before 36 months, with a median age of 26 months for first ASD evaluation and median age of 33 months for diagnosis. The data showed an overall increase of early diagnosis by age 48 months in the Early ADDM 2016 data compared to the 8-year-olds in the 2016 ADDM cohort.

Implications: The disparity in ASD prevalence among Black and White four-year-old children decreased in 2016, and more children were receiving early diagnosis in 2016 than in 2014. Prevalence of co-existing ID was higher in 2016 than in 2014, suggesting that early evaluation increased early identification of ID. Despite this progress, efforts are needed to reduce the disparities in early ASD diagnosis between four-year-old boys and girls. Although 2016 ADDM data showed that eight-year-old girls with ASD were more likely to have co-existing ID than eight-year-old boys with ASD, there was no difference among four-year-old children, suggesting a need to assess how ID is evaluated and if it affects disparities in ASD prevalence across boys and girls.