A new study published in the journal Pediatrics reveals that Black children are more likely than children of other races to receive a delayed autism diagnosis. This may explain why Black kids with this developmental disorder experience a higher rate of intellectual disability, reports Spectrum.

Children who aren’t diagnosed early can miss out on age-appropriate and autism-specific care as well as the ability to improve their cognition.

For the study, researchers interviewed the parents of 584 Black children with autism to compile timelines of each family’s experience, including the developmental outcomes for these kids in comparison with their siblings. Results showed a three-year delay in diagnosis for Black children with autism.

Most parents expressed concerns about their child’s development around 23 months old and told a professional six months later. However, their child did not receive an autism diagnosis until they were over age 5.

In addition, more than one third of families said they experienced long wait times to see a professional, with 14% visiting a specialist at least six times before their child received a diagnosis. A third of families believed that a lack of available professionals factored into their child’s delayed diagnosis.

Findings also showed that the high rate of intellectual disability among Black children (47% versus 27% among white children) wasn’t associated with their family’s income or parents’ education, meaning poverty couldn’t be the cause. Additionally, neither gestational age at birth nor the extent to which IQ varies among immediate family members was associated with the prevalence of this problem.

Researchers concluded that the results suggested that a lack of access to services very likely hindered these children. Unlike youngsters of other races with autism who began receiving care one to three years before their autism diagnosis, Black children didn’t receive such care until it was too late.

Nevertheless, not all scientists believe that a delayed diagnosis is the main cause for the disparity between Black kids and other children with autism. Some believe that other factors linked to low IQ, such as lead poisoning, quality of nursery schools and kids living in neighborhoods perceived to be dangerous.

“There’s no doubt that African-American children are underserved and receive delayed interventions,” said Walter Zahorodny, PhD, associate professor of pediatrics at Rutgers New Jersey Medical School in Newark, who was not involved in the investigation. “Certainly, that’s something that deserves respect and action.”

For related coverage, read “Brain Scans Taken at an Early Age May Help Predict Autism in Babies.”