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Disparities in the Clinical Characterization Profiles of African American Vs Caucasian Individuals with Autism
Studies examining differences between African-American and Caucasian individuals with autism have yielded equivocal findings. African-American individuals are more likely to have developmental delays (e.g., Cuccaro et al., 2007), but are less impaired on measures of adaptive behavior and executive functioning and exhibit less externalizing and stereotypical behavior compared to Caucasian peers (Ratto et al., 2015; Sell et al., 2012). Factors underlying this discrepancy remain unclear, but likely contribute to previous findings of delays in diagnosis, misdiagnosis of disruptive behavior disorders, and less access to care for African-American individuals with autism (e.g., Mandell et al., 2009).
Objectives:
This study compares phenotypic profiles of African-American and Caucasian school-age individuals with ASD on measures of cognition, adaptive functioning, and diagnostic symptomatology.
Methods:
Participants included 184 individuals (93 African-American, 91 Caucasian) with Autism Spectrum Disorder ranging in age from 3 to 18 years (mean=99.62 months; SD=46.81) who received a clinical evaluation through research studies at the Marcus Autism Center. Measures included the Differential Ability Scales, 2nd Edition (DAS-II); the Autism Diagnostic Observation Schedule, 2nd Edition (ADOS-2); the Autism Diagnostic Interview, Revised (ADI-R), and the Vineland Adaptive Behavior Scales, 2nd Edition, Survey Form (Vineland-II).
Results:
ANOVA analyses on a preliminary sample (93 African-American, 21 Caucasian) revealed significant racial differences; African-American individuals scored significantly lower than Caucasian individuals across measures of verbal, nonverbal, and overall cognitive ability [DAS-II GCA: F(1,63)=24.56, p<.001], and adaptive communication [Vineland-II Communication: F(1,106)=5.25, p<.05], and exhibited significantly greater restricted and repetitive behavior [ADOS-2 RRB: F(1,99)=12.49, p<.01]. Adaptive communication differences disappeared when controlling for cognition.
Given the significant difference in cognitive ability, analyses were repeated in a subset of participants without cognitive impairment (i.e., DAS-II GCA>70; 21 African-American, 19 Caucasian). Within this sample, significant differences remained across measures of cognitive ability. Differences in ADOS RRB were no longer significant. However, African-American individuals without cognitive impairment had significantly lower adaptive socialization scores, even after controlling for cognitive ability [Vineland-II Socialization: F(1,31)=13.12, p<.01]. Across analyses, no differences were found on Vineland Internalizing or Externalizing scales or on ADI-R scores.
Conclusions:
In summary, we found that African-American individuals exhibited significantly lower levels of cognition and higher levels of restricted and repetitive behaviors than Caucasian individuals. Only 5% of the Caucasian sample had cognitive scores below 70 compared to 47% of the African-American sample. When limiting the sample to the “cognitively-able” range, African-American individuals still exhibited lower cognition in addition to adaptive socialization deficits, but no differences in stereotypical behaviors, suggesting that the higher RRB levels noted in the total sample were likely influenced more by cognitive impairment than autism symptomatology. In contrast, African-American individuals’ adaptive socialization deficits remained even after controlling for cognitive functioning and even in the absence of differences in autism symptomatology. These findings help clarify the discrepancy in clinical profiles of African-American and Caucasian individuals with autism, highlight areas for targeted intervention, and raise questions about how to most appropriately conceptualize “level of functioning.”