Autism Diagnoses in Canadian Youth Surge Over 20 Years: Report

A man walks with his son, who is autistic, to a school in Los Angeles in a file photo. AP Photo/Damian Dovarganes

The number of Canadian children and adolescents being diagnosed with autism has risen sharply over the past two decades, a recently published government report says.

Data compiled by Canada’s Public Health Agency indicates the rate of newly identified autism cases went from 35 per 100,000 children and youth in 2000-2001 to 365 per 100,000 in 2023-2024.

That translates into an estimated one in 44 children or adolescents receiving an autism diagnosis in 2023-2024, compared to one in 714 in 2000-2001, the agency said in its newly released report.

“Several factors may have played a role in the overall rise in newly identified cases and prevalence of autism, such as increased awareness, expanded diagnostic criteria, and guidelines promoting early detection,” reads the report, which was first obtained by Blacklock’s Reporter. “The specific factors and the extent of their contribution to this rise remain unknown.”

The data used by the agency in its report was collected by the government’s Canadian Chronic Disease Surveillance System (CCDSS). All data is reported by fiscal year, from April 1 to March 31.

The system provides estimates of both the prevalence of autism as well as the newly identified cases of diagnosed children and youth, according to the CCDSS autism case definition. It is categorized by age, sex, province, and territory over time.

The CCDSS data indicates that the prevalence estimates and rates of newly identified autism cases vary from province to province. This prevalence ranged from one in 75 children or teens in Saskatchewan, to one in 34 in Prince Edward Island in 2023-2024.

The rate of newly identified cases in 2024 also ranged from 260 per 100,000 children and youth in Nova Scotia to 551 per 100,000 in British Columbia.

The rate in P.E.I sat at 470 per 100,000, followed by 409 in Ontario, 319 in Alberta, 298 in Northwest Territories, 288 in Yukon, 285 in Saskatchewan, 278 in Québec, and 270 in Manitoba. Data was not submitted for New Brunswick, Newfoundland and Labrador, and Nunavut.

The report noted that the identification of autism cases within the health administrative databases used by the CCDSS may differ among the provinces and territories, due to variations in data recording practices, access to health care, and autism evaluation procedures.

“Despite these differences, data from all provinces and territories included in the CCDSS showed increases in autism estimates over time,” the report said.

Gender and Age of Diagnosis

Autism has historically been more frequently diagnosed in boys than in girls. While that is still true, the gap between the two genders has closed significantly since 2001.

The agency report shows that the gender disparity has been cut almost in half.  The number of new autism cases in boys was four times greater than in girls in 2000-2001, but this ratio decreased to 2.3 by 2023-2024.

“In alignment with recent research results in other countries, this trend suggests an increasing recognition and diagnosis of autism in females over time,” the report says.

Gender prevalence was not the only change. The age at which children are being diagnosed has also evolved over the past two decades.

Autism prevalence in the CCDSS is lower among children aged one to four when compared to older age groups,  but the rate of newly identified autism cases is presently highest among the youngest children and has been steadily increasing over time.

The newly identified autism case rate was similar in children ages one to four and five to nine from 2000–2001 to 2011–2012, sitting at approximately 160 cases per 100,000 children in 2012 in both age groups.

By 2023–2024, the rate of newly identified cases in the one to four age group had increased to 689 per 100,000, surpassing the five to nine age group which reached 489 per 100,000.

“This shift highlights a growing emphasis on early identification and diagnosis, which can lead to earlier support for children to help them reach their full abilities,” the report says.

The Public Health Agency also relies on data from the Canadian Health Survey of Children and Youth (CHSCY) to determine autism rates, the report notes.

While the CCDSS uses health administrative data, the CHSCY is strictly self-reported. Despite these differences, both consistently show that autism prevalence has increased over time and varies according to region.

“By combining insights from these two national sources, we gain a more complete picture of how many Autistic children and youth live in Canada,” the report reads. “The trend observed in the data indicates a growing demand for programs and services to support autistic people across the lifespan and their families.”

The U.S. Centers for Disease Control and Prevention has initiated an investigation into the cause of autism. The U.S. agency says it’s possible vaccines could be linked to autism—a reversal of its previous stance. The U.S. CDC website was updated in November 2025 at the direction of secretary of U.S. Health and Human Services, Robert F. Kennedy Jr., to say studies have not conclusively ruled out a link between infant vaccines and autism.

Health Canada has maintained its stance that there is no link between vaccines and autism and Canadian health officials have criticized the U.S. move, saying it goes against the global scientific consensus.