Convergent neural correlates of prenatal exposure to air pollution and behavioral phenotypes of risk for internalizing and externalizing problems: Potential biological and cognitive pathways.

Humans are ubiquitously exposed to neurotoxicants in air pollution, causing increased risk for psychiatric outcomes. Effects of prenatal exposure to air pollution on early emerging behavioral phenotypes that increase risk of psychopathology remain understudied. We review animal models that represent analogues of human behavioral phenotypes that are risk markers for internalizing and externalizing problems (behavioral inhibition, behavioral exuberance, irritability), and identify commonalities among the neural mechanisms underlying these behavioral phenotypes and the neural targets of three types of air pollutants (polycyclic aromatic hydrocarbons, traffic-related air pollutants, fine particulate matter < 2.5 µm). We conclude that prenatal exposure to air pollutants increases risk for behavioral inhibition and irritability through distinct mechanisms, including altered dopaminergic signaling and hippocampal morphology, neuroinflammation, and decreased brain-derived neurotrophic factor expression. Future studies should investigate these effects in human longitudinal studies incorporating complex exposure measurement methods, neuroimaging, and behavioral characterization of temperament phenotypes and neurocognitive processing to facilitate efforts aimed at improving long-lasting developmental benefits for children, particularly those living in areas with high levels of exposure.

Cognitive correlates of autism spectrum disorder symptoms.

Due to the diverse behavioral presentation of autism spectrum disorder (ASD), identifying ASD subtypes using patterns of cognitive abilities has become an important point of research. Some previous studies on cognitive profiles in ASD suggest that the discrepancy between verbal intelligence quotient (VIQ) and performance IQ (PIQ) is associated with ASD symptoms, while others have pointed to VIQ as the critical predictor. Given that VIQ is a component of the VIQ-PIQ discrepancy, it was unclear which was most driving these associations. This study tested whether VIQ, PIQ, or the VIQ-PIQ discrepancy was most associated with ASD symptoms in children and adults with ASD (N = 527). Using data from the Autism Brain Imaging Data Exchange (ABIDE), we tested the independent contribution of each IQ index and their discrepancy to ASD symptom severity using multiple linear regressions predicting ASD symptoms. VIQ was most associated with lower symptom severity as measured by the Autism Diagnostic Observation Schedule (ADOS) total score, and when VIQ was included in models predicting ASD symptoms, associations with PIQ and IQ discrepancy were not significant. An association between VIQ and ASD communication symptoms drove the association with ASD symptom severity. These results suggest that associations between ASD communication symptoms and IQ discrepancy or PIQ reported in prior studies likely resulted from variance shared with VIQ. Subtyping ASD on the basis of VIQ should be a point of future research, as it may allow for the development of more personalized approaches to intervention. LAY SUMMARY: Previous research on links between autism severity and verbal and nonverbal intelligence has produced mixed results. Our study examined whether verbal intelligence, nonverbal intelligence, or the discrepancy between the two was most related to autism symptoms. We found that higher verbal intelligence was most associated with less severe autism communication symptoms. Given the relevance of verbal intelligence in predicting autism symptom severity, subtyping autism on the basis of verbal intelligence could lead to more personalized treatments.