Maternal Education Predicts Early ASD Diagnosis in Black and White Toddlers with Higher Cognitive Functioning

Background:  Recent studies on disparities in ASD across racial and ethnic groups highlight the role of cognition as an essential modulator variable. Magnusson et al. (2012) reported higher rates of low-functioning ASD for minorities in Sweden, and Durkin et al. (2010) found a positive association between socioeconomic status and ASD in all US ethnic groups, but no association when ASD presented with cognitive delays. ASD has also been found to be less prevalent but more severe in minorities in the US (Mandell et al., 2009).

Objectives:  This study explores level of functioning in newly diagnosed toddlers with ASD across two different sociodemographic variables: race and socioeconomic status.

Methods:  131 toddlers ages 10 to 30 months (Mean=22.13, SD=4.32) were recruited from a clinically-referred sample; 100 participants were white (52 ASD; 26 DD; 22 TYP; 25 females) and 31 participants were black (17 ASD; 12 DD; 2 TYP; 7 females). Evaluations included the Autism Diagnostic Observation Schedule, Toddler Module, the Vineland Adaptive Behavior Scales, Second Edition, and the Mullen Scales of Early Learning. Race was computed by self-identification, and SES by level of maternal education (college degree or more and less than college degree). Mullen derived IQ scores were grouped as higher or lower than 70 (High IQ; Low IQ).

Results: Results showed no significant difference in age of diagnosis between racial groups. Chi-Square analyses revealed no significant effects of race by diagnosis, race by maternal education, or race by IQ, but did reveal a significant effect for maternal education by diagnosis, with 46% of mothers of children with ASD having a college degree or higher compared to 31% of the DD sample [χ²(2)=10.65; p<.01]. Age of diagnosis in children with ASD with High Verbal IQ was significantly lower if their mothers’ education was a college degree or higher [M=16.86m, SD=1.70] vs. some college or less [M=23.29m, SD=6.01, t(12)=12.62, p<.05). Similarly, children with High Nonverbal IQ were diagnosed with ASD earlier if their mothers had a college degree or higher [M=21.00m, SD=4.71] compared to less than college [M=24.10m, SD=2.43, t(43)=7.42, p<.05]. Conversely, maternal education did not predict any differences in age of diagnosis for children with ASD with Low IQ. For the DD samples of both Low and High IQ, there were no significant effects of maternal education on age of diagnosis.

Conclusions:  In a biracial sample of clinically-referred toddlers that is relatively homogeneous in terms of maternal education and cognitive functioning, higher maternal education predicts earlier diagnosis of ASD in cognitively intact children, but not those with delays. Maternal education is not associated with earlier diagnosis of DD. These results corroborate Durkin et al. (2010), showing less ethnic differences in families with higher SES, and a greater SES gradient in children without cognitive delays (regardless of race). Given that ASD unfolds with development, future studies should focus on young children that are diagnosed early in order to characterize the true status of cognitive functioning in autism and disentangle its interaction with sociodemographic factors.