Characterized by changes in neurodevelopment, Autism Spectrum Disorder (ASD) is a condition whose prevalence has progressively increased over the years. According to the 2021 report by the Centers for Disease Control and Prevention (CDC), an agency of the United States Department of Health and Human Services, whose data is also used by Brazilian professionals due to the lack of national data on the condition, one in every 44 children up to 8 years of age is diagnosed with autism. Despite presenting some characteristic signs, researchers and health professionals are still seeking to understand in depth the causes of these changes and their different manifestations. Researchers at the Santos Dumont Institute (ISD), in Macaíba, Rio Grande do Norte, have taken a step towards helping to understand the manifestation of autism by analyzing brain cells. 

Studies conducted by the University of California published in 2011 found that the brain growth curve of people with autism in the early stages of life differs from those without the condition, with a tendency for children with ASD to have a larger brain and a larger number of neurons during the first years of childhood. 

Based on the analysis of brain images of 22 children, of which 11 had a diagnosis of autism and 11 did not have the condition, made available by Allen Institute for Brain Sciences, neuroengineer and psychologist Lívia Nascimento sought to investigate how these different brains manifested characteristics at the cellular level in a specific area, whose functions are associated with activities that can be affected in people with ASD, such as communication and social interactions, called the dorsolateral prefrontal cortex. 

The analyses, published in the form of an article in the scientific journal Journal of Autism and Developmental Disorders (“Periódico sobre Autismo e Transnos do Desenvolvimento” in free translation), revealed important changes, which add to recent discoveries in the search for a better understanding of the brain of an autistic person. “There is already an idea being formed in the literature about autism, which talks about greater brain growth during childhood, which would also be accompanied by a greater presence of neurons in these individuals”, explains Lívia Nascimento. 

According to the neuroengineer, this greater presence of neurons could imply greater difficulty for the brain to organize these cells into certain areas and functions. “In our study, we were able to confirm much of what had already been presented in the literature, but we also discovered something new, which concerns the positioning of these neurons in the area analyzed,” she adds. 

The area investigated by the researchers, the dorsolateral prefrontal cortex, has a particular organization of cells, in the form of layers, to which neurons migrate during development. “When neurons were going to migrate to these layers, they probably migrated in a disorganized way, resulting in regions with more neurons and others with fewer,” he says. 

Discoveries may help in differential diagnoses

ISD research professor Felipe Porto Fiuza, supervisor of the research conducted by Lívia during her Master's in Neuroengineering that resulted in the article published in the international journal, explains that the research could help in the search for a common denominator in ASD, whose diagnosis still presents some challenges. 

“Diagnosing autism is somewhat challenging because there are several subtypes of autism, it is a very large spectrum, with a heterogeneity of symptoms that manifest themselves to different degrees. We look at the brain to try to have a more objective measurement, at a physiological level, of whether there is any type of impact and whether this is replicable among different individuals. We seek a common denominator for these different cases, which will be able to better support this understanding of what autism is at a cellular level,” he says. 

Felipe Fiuza points out that in addition to the greater number of neurons, they also found that these brain cells had difficulty expressing certain genes, revealing changes in their functioning compared to what would be expected for this type of cell. “In addition, they are organized differently, with some layers having many more cells than others, which suggests that autism is related to an abnormal migration of neurons and their different positioning. The problem with having many neurons in these layers is that they compete for nutrients and thus hinder the growth of the other during development,” he adds.  

For the neuroengineer, studies must be increasingly in-depth so that the population can understand the different manifestations of ASD. “These are studies that are being added so that we can better understand ASD, its characteristics and why we have different levels and expressions. Understanding these explanations can help us better understand who our patient, our child, our neighbor is... we can understand where it comes from and why we have these different clinical manifestations”, says Lívia Nascimento.