Potential Caveat For Early ASD Diagnosis In Infants

     Autism spectrum disorder (ASD) is a developmental disability that can produce a variety of different social and behavioral challenges upon those who are affected. Depending on the spectrum of Autism, people with ASD learn, think, and problem-solve differently than those who are not on the spectrum. ASD typically involves early brain overgrowth affecting several cortical and subcortical regions such as prefrontal and temporal cortices. These affected areas mediate the symptoms that a person with ASD experiences. Despite the increasing number of diagnoses, ASD is hard to diagnose because it is not detectable by medical tests but instead dependent on developmental and behavioral tracking. ASD can sometimes be detected at 18-months but many individuals do not receive a confirmed diagnosis until they are older. Some early signs of ASD include: avoiding eye contact, having little interest in other children or caretakers, limited display of language, or getting upset by minor changes in routine (“Screening and Diagnosis of Autism Spectrum Disorder”). 

In the article, "Face-sensitive brain responses in the first year of life", Guy and colleagues sought to examine the changes in neural response of infants to facial stimuli. Previous studies on adults have shown that the N170, located in the middle and posterior fusiform gyrus, is linked to the processing of facial stimuli. The study analyzed ERPs of infants that were face sensitive which involves P1, N290, P400, and Nc. Over a hundred infants were recruited and presented with stimuli consisting of pictures of faces and objects on various backgrounds. During the three experimental procedures, the ECG electrodes of the infants were used to determine the attention of the infants while the EEG electrodes to analyze the neural responses and calculate the amplitudes. The results depicted that the amplitudes of the ERPs increased in older infants 9+ months. The results of this study have lead Guy and colleagues to explore the possibility of using ERP analysis in diagnosing ASD in infants. 

In a separate study by Stoner and colleagues, "Patches of Disorganization in the Neocortex of Children with Autism", examined the neocortical architecture of children after the onset of autism by utilizing RNA in situ hybridization with a panel of layer- and cell-type–specific molecular markers to phenotype ASD. The study observed that children with ASD displayed focal disruptions of cortical laminar architecture in their cortices. Their data supported the idea of a potential dysregulation of layer formation and layer-specific neuronal differentiation at prenatal developmental stages of infants with ASD. In Guy’s study, the ERPs of older infants displaying proper development in facial stimuli response were larger in comparison to younger infants or infants that may have ASD. Stoner’s study could serve as supplemental information to support the results of Guy’s study as to why the ERPs were larger in normal developing infants rather than ASD infants. This could also be a potential caveat in future studies for early ASD diagnosis in order to create reliable medical tests. 

Citations

• Conte, Stefania, et al. “Face-Sensitive Brain Responses in the First Year of Life.” NeuroImage, vol. 211, 2020, p. 116602., doi:10.1016/j.neuroimage.2020.116602. 

• Stoner, Rich, et al. “Patches of Disorganization in the Neocortex of Children with Autism.” New England Journal of Medicine, vol. 370, no. 13, 2014, pp. 1209–1219., doi:10.1056/nejmoa1307491. 

• “Signs and Symptoms of Autism Spectrum Disorders.” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 29 Mar. 2021, www.cdc.gov/ncbddd/autism/signs.html.