Autism Spectrum Disorders In Hispanics and Non-Hispanics

Background:  ASD prevalence varies by ethnicity, where Hispanics have reportedly lower prevalence.  Comparative studies between ethnic groups may unveil differences in autism profiles that could potentially provide us with better and more culturally appropriate approaches for diagnosis and treatment of ASD.  Furthermore, this type of study may suggest explanations for the lower prevalence of ASD seen in Hispanics.         

Objectives:  To describe demographic and phenotypic differences potentially relevant to ASD in a comparison between Hispanics and non-Hispanics. 

Methods:  The Childhood Autism Risks from Genetics and the Environment (CHARGE) study is an ongoing population-based case-control study with subjects sampled from three strata: children with autism (AU) or autism spectrum disorder (ASD), children with developmental delay (DD) but not autism, and children selected from the general population (GP).  Study participants: a) are between the ages of 24 and 60 months, (b) live with at least one biologic parent, (c) have a parent who speaks English or Spanish, (d) are born in California, and (e) reside in one of the catchment areas of a specified list of Regional centers in California.  This study population consisted of 827 children. Diagnosis of AU and ASD was confirmed in all subjects using the Autism Diagnostic Interview-Revised (ADI-R) and the Autism Diagnostic Observation Schedules (ADOS).  Other data collected and compared for all participants include demographics, household language use, adaptive and maladaptive behavior scores, and cognitive scores.  We also examined the relationship between multiple language exposure and language function and scores of children.    

Results:  Among GP control participants, a larger percent of Hispanics met criteria for atypical development (10.1% vs. 0.5%) and delayed development (9% vs. 3.2%) compared to non-Hispanics (p<0.0001).  Among those children recruited with DD, approximately 20% of both Hispanics and non-Hispanics met criteria for ASD or AU.  Compared with non-Hispanic households, multiple language use was far more common in Hispanic households (72.7% vs. 37.6% in cases, 66.2% vs. 30.7% in TD controls, 81.8% vs. 50.7% in DD controls).  Among cases, regression status and language function were not significantly different between ethnic groups.  Non-Hispanic cases also demonstrated higher cognitive ability on the composite score for the Mullen Scales of Early Learning (MSEL), but not the Vineland Adaptive Behavior Scales (VABS).  For both cases and TD controls, Hispanics scored significantly lower on receptive language and expressive language subscales of MSEL.  Speaking to a child 25-50% time in a second language was associated with lower scores on expressive (p=0.0005 TDs, p=0.003 AU/ASD) and receptive language subscale scores (p=0.003 TDs, p=0.06 AU/ASD) for both typically developing children and children with ASD within the 2-5 year age range.    

Conclusions:  Overall, the CHARGE Hispanic group displayed more similarities than differences compared to non-Hispanics in terms of autistic phenotypes and maladaptive & adaptive scores for cases.  The relationship between multiple language use and cognitive scores warrants a closer look.