New research shows that the presence or absence of intellectual disability (ID) and autism spectrum disorders (ASD) varies with risk factors such as gender, parental age, maternal ethnicity, and maternal level of education.
The study also shows that household income level has no association with either ID or ASD, in contrast to what other studies have suggested.
ASDs are a group of childhood neurodevelopmental disorders characterized by problems with social interaction, communication, and restricted and unusual behaviors. ASDs vary widely in severity and may be accompanied with or without intellectual disability. Amid a significant increase in the reported prevalence of ASDs, the Centers for Disease Control and Prevention (CDC) has recognized autism as an urgent public health concern and stressed the importance of characterizing risk factors.
"ASDs represent a diverse group of conditions that may have different causes, and children with ASDs, either with or without ID, represent opposite ends of the autism spectrum," says Judith Pinborough-Zimmerman, first author on the study. "By identifying risk factors associated with ASDs, we may be able to gain a better understanding of the underlying causes of autism."
Pinborough-Zimmerman and her colleagues identified children with ASD and ID in a three-county area surrounding Salt Lake City through the Utah Registry of Autism and Developmental Disabilities (URADD), a multiple-source, population-based surveillance program. They evaluated a variety of demographic factors and found that children with ASD but not ID were significantly more likely to be male and to have mothers of white, non-Hispanic ethnicity.
Children with both ASD and ID were also more likely to be male, but were more likely to have mothers older than 34 years of age. Children who had ID but not ASD were significantly more likely to have fathers older than 34 years of age and significantly less likely to have mothers with more than 13 years of education.
"Demographic risk factors, such as male gender and parental age have been well-described," says Pinborough-Zimmerman. "However, the way in which socioeconomic factors are associated with the development of ASDs is poorly understood."
"This study, despite the small sample size, is an example of the importance of exploring the many variables, that in combination, may result in an increase risk of developing ASD," says Dr. Harper Randall, medical director for the Division of Family Health and Preparedness, UDOH.
According to Pinborough-Zimmerman, the strength of this study lies in its broad ascertainment methods, which utilized multiple educational and health source records to include a wide spectrum of ASD cases. This study was also unique in analyzing socio demographic risk factors for ASD and ID, both independently and together.
REHACARE.de; Source: University of Utah