Findings from 2018 data

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?

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

ASD identification of Minnesota 4-year-olds had an incidence of 1.8 times the rate of 8-year-olds, which is higher than the incidence rate of 1.6 times the rate of 8-year-olds of all ADDM sites.

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 sex/gender, race and ethnicity

Prevalence estimate

Prevalence per 1,000 children

95% confidence interval per 1,000


1 in 44





1 in 29





1 in 100




Asian or Pacific Islander

1 in 31




Black, Non-Somali, Non-Hispanic

1 in 54




Black, Somali

1 in 21





1 in 41




White, Non-Hispanic

1 in 60




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<.001, Black, Somali children had a higher ASD prevalence than White, non-Hispanic; Black, non-Somali, non-Hispanic; and Hispanic children.

What do the sex and race/ethnicity differences in prevalence rates tell us?

Somali 4-year-old children had a higher ASD prevalence than Black-non-Somali, Hispanic, and White 4-year-old children using a p-value of <.001.

Tracking Area

The tracking area included parts of three counties (Anoka, Hennepin, Ramsey) including the large metropolitan city of Minneapolis.

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

  • American Indian or Alaska Native - 2%
  • Asian or Pacific Islander – 8%
  • Black, non-Somali, non-Hispanic – 20%
  • Black, Somali - 5%
  • Hispanic –11%
  • White, non-Hispanic – 53%

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:

We found varying prevalence rates across racial and ethnic groups in Minnesota. Among 4-year-olds, Black-Somali children had a higher ASD prevalence than other groups. Among 8-year-olds, Black-Somali and Black-non-Somali children had a higher ASD prevalence than Hispanic children. 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 8-year-olds), 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.