The Minnesota-Autism and Developmental Disabilities Monitoring Network (MN-ADDM) is part of the Autism and Developmental Disabilities Monitoring (ADDM) Network, a group of programs funded through the Centers for Disease Control and Prevention (CDC) to estimate the number of children with autism spectrum disorder (ASD) and other developmental disabilities living in different areas of the United States. MN-ADDM monitors the prevalence of ASD and intellectual disability (ID) in parts of Anoka, Hennepin, and Ramsey counties.

Autism spectrum disorder is a developmental disability that can cause significant social, communication and behavioral challenges. There is often nothing about how people with ASD physically look that sets them apart from other people, but people with ASD may communicate, interact, behave, and learn in ways that are different from most other people. The learning, thinking, and problem-solving abilities of people with ASD can range from gifted to severely challenged. Some people with ASD need a lot of help in their daily lives; others need less. Intellectual disability means that a person has difficulty learning at an expected level and functioning in daily life. In this report, intellectual disability is measured by intellectual quotient (IQ) test scores of less than or equal to 70.

The ADDM Network provides population-based prevalence estimates of ASD and other developmental disabilities across sites that can be compared over time. The combined data from the various ADDM sites can help inform us about:

  • characteristics of children with ASD,
  • whether ASD is more common in some groups of children than others and if those differences change over time, and
  • the impact of ASD and related conditions upon children, families, and communities in the United States.

This project does not examine what causes ASD. Our focus is on providing data and training that helps policymakers, educators, communities, providers, families, and individuals make informed decisions and support children with autism and their families.

This year, MN-ADDM estimated prevalence of ASD among 8-year-old and 4-year-old children.

Key findings from 2018 data: 8-year-olds

How many 8-year-old children were identified with ASD in Minnesota?

2.8 percent or 1 in 36 children were identified with ASD in Minnesota.

Using data from 2018, MN-ADDM researchers found 1 in 36 (2.8%) 8-year-old children were identified with ASD. This is higher than the overall ADDM Network prevalence of 8-year-old children identified with ASD (1 in 44 or 2.3%) in the United States where the CDC tracked ASD in 2018.

When were children first diagnosed with ASD in Minnesota?

The median age of first ASD diagnosis was 5 years, 3 months. Of the children identified with ADS, 45.4% had a recorded evaluation by 36 months of age

What was the percentage of children with ID in Minnesota?

Minnesota had intelligence quotient (IQ) data available for 81% of children identified with ASD. Of those children, 29% had intellectual disability. Intellectual disability is defined as an IQ score of 70 or lower.

Which children were more likely to be identified with ASD in Minnesota?

Boys were 4.2 times more likely to be identified with ASD than girls.

Prevalence of ASD in 8-year-old children in Minnesota by gender, race and ethnicity

Prevalence estimate

Prevalence per 1,000 children

95% confidence interval per 1,000

Overall

1 in 36​

2.8%

27.5

24.5–30.9​

Males

1 in 23

4.3%

43.7

38.5–49.7

Females

1 in 100

1.0%

10.4

7.9–13.6

White, Non-Hispanic 

1 in 40​

2.5%

25.0

21.1–29.7 ​

Black, Non-Hispanic 

1 in 30​

3.3%

33.0

26.6–40.7* ​

Asian or Pacific Islander

1 in 47​

2.1%

21.5

13.6–33.7 ​

Hispanic

1 in 55​

1.8%

18.1

12.4–26.4 ​

Somali

1 in 29

3.4%

35

22.2-54.6

201 American Indian or Alaska Native children were included in the denominator but were not included in prevalence estimations due to low numbers of children with ASD

API: Asian/Pacific Islander

291 Hmong children were included in the non-Hispanic API group but were not analyzed separately due to low case numbers.

p<.05, Black, non-Hispanic children had a higher ASD prevalence than White, non-Hispanic and Hispanic children.

What do the differences in prevalence rates for White and Black and Hispanic children tell us?

Black 8-year-old children had a higher ASD prevalence than White and Hispanic 8-year-old children using a p-value of <.05.

How common is intellectual disability for children who also have ASD?

Among children identified with ASD who had IQ information available, 29% also had intellectual disability.

  • Intelligence quotient (IQ) scores were available for 81% of children identified with ASD by MN-ADDM. Intellectual disability is defined as IQ score ≤ 70.

Other key findings:

About 45% of children identified with ASD received an evaluation by age 3 years.

Even though ASD can be diagnosed as early as age 2, about half of children were not diagnosed with ASD until 5 years and 3 months.

Key findings from 2018 data: 4-year-olds

How many 4-year-old children were identified with ASD in Minnesota?

2.3 % or 1 in 44 children were identified with ASD in Minnesota.

Using data from 2018, MN-ADDM researchers found 1 in 44 (2.3%) 4-year-old children were identified with ASD. This is higher than the overall ADDM Network prevalence of 4-year-old children identified with ASD (1 in 59 or 1.7%) in the United States where the CDC tracked ASD in 2018.

When were 4-year-old children first diagnosed with ASD in Minnesota?

Compared with children aged 8 years, Minnesota 4-year-olds had a higher cumulative incidence than 8-year-olds, meaning ASD identification is happening in the younger age group than the older age group. ​Cumulative incidence refers to the rate of identification over time. Minnesota 4-year-olds were identified at 1.8 times the rate of 8-year-olds.

What was the percentage of 4-year-old children with ID in Minnesota?

Minnesota had intelligence quotient (IQ) data available for 66% of 4-year-old children identified with ASD. Of those children, 57% had intellectual disability. Intellectual disability is defined as an IQ score of 70 or lower.

Which children were more likely to be identified with ASD in Minnesota?

Among 4-year-olds, boys were 3.3 times more likely to be identified with ASD than girls.

Prevalence of ASD in 4-year-old children in Minnesota by gender, race and ethnicity

Prevalence estimate

Prevalence per 1,000 children

95% confidence interval per 1,000

Overall

1 in 44

2.3%

22.8

20.1–25.8

Males

1 in 29

3.5%

34.8

30.2–40.0

Females

1 in 100

1.0%

10.6

8.1–13.7

White, Non-Hispanic

1 in 60

1.7%

16.6

13.6–20.3*

Black, Non-Hispanic

1 in 43

2.4%

23.5

18.4–30.0*

Asian or Pacific Islander

1 in 32

3.1%

30.8

21.3–44.5*

Hispanic

1 in 41

2.4%

24.4

17.0–34.8

Somali

1 in 21

4.7%

48.7

33.4-70.4

American Indian or Alaska Native children were included in the denominator but were not included in prevalence estimations due to low numbers of children with ASD

*p<.05, Black, non-Hispanic children and Asian/Pacific Islander children had a higher ASD prevalence than White, non-Hispanic children.

What do the differences in prevalence rates for White and Black and Hispanic 4-year-old children tell us?

Black and Asian 4-year-old children had a higher ASD prevalence than White 4-year-old children using a p-value of <.05.

This information is based on the analysis of data collected from the health and educational records of children who were 4 and 8 years old in 2018. In addition to the race/ethnicity categories routinely studied by CDC, in MN we are interested in understanding prevalence for children in our Hmong and Somali communities.

Tracking area: Parts of three counties (Anoka, Hennepin, Ramsey) including the large metropolitan city of Minneapolis.

8-year-old children in the tracking area included 10,081 children of the following race and ethnicity 

  • White, non-Hispanic –  51% 
  • Black, non-Hispanic – 25% 
  • Asian or Pacific Islander – 8% 
  • Hispanic –14% 
  • American Indian or Alaska Native - 2%

4-year-old children in the tracking area included 10,529 children of the following race and ethnicity 

  • White, non-Hispanic –  53% 
  • Black, non-Hispanic – 25% 
  • Asian or Pacific Islander – 8% 
  • Hispanic –11% 
  • American Indian or Alaska Native - 2%

Limitations and Implications

This is the third time Minnesota data has been included in findings from the ADDM Network. The findings in this report reflect a small number of children concentrated in a large metropolitan area. The higher prevalence estimate in Minnesota, compared to ADDM-wide estimates, is not unanticipated for a large metropolitan area.

In Minnesota, there are differences between the proportions of boys and girls identified with ASD, with more boys than girls. This is consistent with previous estimates. (Note: the ADDM project only collects data on males and females and does not include sexual orientation or gender identification information.)

In Minnesota, we identify ASD much later than when first concerns are reported. The median age of the first ASD diagnosis for 8-year-olds was 5 years and 3 months, which was the latest age across the ADDM Network. This lag is concerning due to the critical importance of early identification and intervention. Many states, including MN have invested in early intervention to help children and families gain access to early intervention services. For example, Minnesota’s Early Intensive Developmental and Behavioral Intervention (EIDBI) Benefit provides early intensive intervention for people with ASD and related conditions. To learn more about the EIDBI benefit follow this link: 

https://mn.gov/dhs/partners-and-providers/news-initiatives-reports-workgroups/long-term-services-and-supports/eidbi/eidbi.jsp

We found varying prevalence rates across racial and ethnic groups in Minnesota. The small number of children in some of these groups makes it difficult to determine whether the rates of children with ASD truly are different across groups. Additionally, the confidence intervals around the prevalence estimates are large (e.g., 13.6-33.7 for Asian/Pacific Islander children), and this tells us we should use caution before drawing conclusions about any differences between groups. As the geographic area for MN-ADDM continues to grow and include more children, we will be better able to judge whether there are true differences in prevalence estimates. If differences are found, it will be important to focus on general health disparities that may influence these differences. 

We found that of the 8-year-old children who had IQ information in their records, 29% had an intellectual disability. Among 4-year-old children with IQ information, 57% had an intellectual disability. The higher rate of intellectual disability in the younger group is not unexpected, as children with ASD with developmental delays are often identified earlier than children with ASD without developmental delays.