Neurodevelopmental Profiles of 4-Year-Olds in the Navajo Birth Cohort Study

Objective

Native American children disproportionally face many risk factors for poor developmental outcomes, including poverty, environmental toxicant exposure, and limited medical and intervention services. To understand these risks, comprehensive documentation of developmental and behavioral phenotypes is needed. In this descriptive study, the neurodevelopment of young Diné (Navajo) children was assessed using standardized assessment instruments in combination with expert clinician judgment.

Method

As part of an ongoing, population-based, prospective birth cohort study, comprehensive neurodevelopmental assessments were conducted of 138 Diné children 3 to 5 years old residing on or near the Navajo Nation. Standardized parent reports, psychiatric examinations, and direct assessments of children’s language, cognitive, adaptive, and social-emotional development, as well as best estimate clinical diagnoses were obtained.

Results

DSM-5 criteria for a neurodevelopmental disorder diagnosis were met by 49% of the sample. Language and speech sound disorders were most common, although autism spectrum disorder was also increased compared with the general population. Though language performance was low among all groups of children with and without neurodevelopmental disorders, children meeting criteria for certain neurodevelopmental disorders showed significantly lower performance on all language measures compared with children not meeting these criteria. Social-emotional, behavioral, and nonverbal cognitive ability were in the average range overall.

Conclusion

Diné children in this study were found to have a high percentage of clinically significant developmental delays. Overall, children presented with a pervasive pattern of depressed language performance across measures, irrespective of diagnosis (or no diagnosis), while other domains of functioning were similar to normative samples. Findings support the need to identify appropriate intervention and educational efforts for affected youth, while also exploring the causes of the specific developmental delays. However, longitudinal studies are necessary to establish best practices for identifying delays and delineating resilience factors to optimize development of Diné children.