Researchers have found that Hispanic children often have undiagnosed developmental delays and large numbers of both Hispanic and non-Hispanic children who first were thought to have developmental delay actually had autism. 

Developmental delay is diagnosed in children who lag behind others in reaching important mental or physical milestones, while autism is characterized by deficits in social interactions and communication behaviors. The symptoms of both disorders can be improved with targeted interventions, with the greatest improvements seen when interventions begin early in life.

The findings are published in the journal Autism. 

The study is one of the largest to date to compare development in Hispanic and non-Hispanic children and researchers have recommend increased public health efforts to improve awareness, especially among Hispanics, about the indicators of developmental delay and autism.

Lead author Virginia Chaidez said the study raises concerns about access to accurate, culturally relevant information regarding developmental milestones and the importance of early detection and treatment. 

"Autism and developmental delay tend to go undiagnosed when parents are not aware of the signs to look for, and the conditions are often misdiagnosed when parents don't have access to adequate developmental surveillance and screening," Chaidez said.

Researchers observed 1,061 children living in California who were between 24 and 60 months of age. They were divided into three groups: children with autism, children with developmental delay but not autism, and children with typical development. All diagnoses were confirmed or changed based on evaluations by MIND Institute clinicians.

The evaluations of Hispanic children were conducted by bicultural and bilingual clinicians in Spanish or English, depending on the primary language used at home. The results for children with at least one Hispanic parent of any race were compared to the results for children of non-Hispanic white parents.

When the outcomes for Hispanic children were compared to non-Hispanic children, the results revealed more similarities than differences in terms of autism profiles, including diagnostic scores, language function, whether or not children lost acquired skills and overall intellectual, social and physical functioning.

Researchers found that 6.3 percent of Hispanic children enrolled in the study who were selected randomly out of the general population met criteria for developmental delay, compared with only 2.4 percent of non-Hispanic participants, which is the expected percentage. 

About 19 percent of Hispanic and non-Hispanic children recruited for the study with developmental delay who actually met criteria for autism.

When the analysis was restricted to bilingual children, a significant relationship also emerged between secondary language exposure (when a child was spoken to 25 to 50 percent of the time in a language other than English) and lower scores on standardized tests of receptive and expressive language. This resulted in lower overall cognitive scores for this group.

Researchers said the results emphasize the importance of considering cultural and other family factors such as multiple language exposure that can affect development when interpreting clinical tests, even when they are conducted in the child's preferred language

"That so many children are slipping through the cracks is disheartening," Robin Hansen, a study coauthor said. "The differences between developmental disabilities can be subtle but important and involve distinct treatment pathways. We need to make sure that all children are getting routine developmental screening, early diagnosis and intervention so they can achieve their fullest potential."