What are the challenges for science in understanding autism?

Despite decades of research, Autism Spectrum Disorder (ASD) remains one of the greatest enigmas in medicine. In very few cases is a specific test able to accurately pinpoint its origin, and science has not yet reached a consensus on what actually triggers the disorder. This gap in knowledge opens the door to doubts, misguided theories, and even false promises of a cure—fertile ground for misinformation to flourish on social media and confuse families seeking answers.

In September, a statement by US President Donald Trump claiming that pregnant women taking paracetamol was responsible for "causing" autism contributed to increased insecurity among the population. But this argument has no scientific basis. "Extensive research has been conducted over the past decade investigating the links between paracetamol use and autism, and to date, no consistent association has been established," said the World Health Organization (WHO) in a statement .

In Brazil, the Ministry of Health stated in a press release that the dissemination of content with this association is "irresponsible and can cause panic and harm to mothers and children." According to data from the 2022 Census collected by the Brazilian Institute of Geography and Statistics (IBGE), the country has approximately 2.4 million people diagnosed with autism. Globally, the WHO estimates that the prevalence of the disorder is one in every 127 individuals.

A 2025 study conducted by the Getulio Vargas Foundation (FGV) in partnership with the National Association for the Inclusion of Autistic People (Autistas Brasil) indicates that the volume of false information about ASD on the internet grew by more than 15,000% between 2019 and 2024 in Latin America and the Caribbean, with Brazil leading in the number of conspiratorial publications and comments.

At least 150 false causes related to autism have been identified, including unfounded claims about the consumption of processed snacks, exposure to 5G radiation, and the administration of vaccine doses. Another 150 false "cures" for the disorder have also been discovered, promoting, for example, electroconvulsive therapy and the ingestion of toxic substances such as chlorine dioxide and colloidal silver.

According to psychologist Guilherme Bracarense Filgueiras, a professor at the State University of Londrina (UEL) in Paraná, these assumptions take advantage of the fact that autism is still considered a mystery to medicine, and go against the necessary steps to support concrete discoveries. "Statements not based on scientific rigor seek to generate impact and engagement, especially on social media," he points out.

But these statements are not harmless — especially when they come from public figures. “False associations fuel guilt and suffering among mothers of children with autism, who may mistakenly come to believe that their choices during pregnancy contributed to the diagnosis,” observes neuropediatrician Marcela Rodríguez de Freitas, professor at the Federal Fluminense University (UFF) in Rio de Janeiro, and secretary of the Scientific Department of Child Neurology of the Brazilian Academy of Neurology (ABN).

Refusal of vaccines and medications can result in untreated infections and a lack of prophylaxis against preventable diseases, increasing the risk of congenital problems, premature birth, and even maternal and fetal mortality.

Why is it a mystery?

Autism can be considered an "enigma" for several reasons. One of them is its exact cause: science has made significant progress in understanding the factors associated with the disorder, but this does not equate to knowing its origin.

According to Filgueiras, around the 1950s and 1960s, some psychological theories argued that autism resulted from a neglectful childhood. The "refrigerator mother theory," as it became known, suggested that children who exhibited characteristics now associated with autism lacked parental emotional warmth, especially maternal warmth.

With the advancement of studies on the subject, this view was replaced by hypotheses based on replicable scientific experiments. In 1977, a study published in The Journal of Child Psychology and Psychiatry , which analyzed twins and their families, demonstrated that the heritability of autism was high and pointed to a strong genetic influence on the condition.

“Since then, it has been possible to recognize specific genetic causes, such as rare pathogenic mutations involving one or a few genes, in approximately 20% to 25% of autism cases, depending on the population studied,” explains biologist Andréa Laurato Sertié, a researcher at the Albert Einstein Israelite Institute for Teaching and Research (IIEP). But these alterations do not account for everything, as they represent only a small fraction of cases. “There is no single genetic mutation found recurrently in all individuals with ASD,” Sertié summarizes.

It is believed that neurodivergence, in most cases, follows a polygenic and multifactorial model. This means that different genetic mutations may not cause autism on their own, but when combined they exceed a certain susceptibility threshold, resulting in the manifestation of autism. Most likely, this process also occurs through interaction with environmental factors.

Different studies highlight evidence that advanced parental age, severe viral or bacterial infections during pregnancy, obstetric complications, and exposure to certain toxic substances can influence the development of ASD. A study published in 2015 in the Journal of Developmental & Behavioral Pediatrics identified that individuals with ASD who have rare genetic risk variants and whose mothers suffered from infections during pregnancy exhibit more pronounced deficits in social interaction and repetitive behaviors. These findings suggest an important interaction between genes and an inflammatory environment in the development of the disorder.

Improvements in diagnosis

Advances in autism studies have also brought changes to diagnostic approaches, as it has become clear how heterogeneous it can be. “The symptoms and degree of impairment vary widely among affected individuals. While some present significant deficits in communication and behavior, others have preserved or even above-average cognitive abilities,” explains Andréa Sertié, who is also a professor at the Albert Einstein Israelite Faculty of Health Sciences (FICSAE).

To keep pace with these changes in the understanding of autism, the Brazilian Society of Child Neurology (SBNI) released new guidelines in September for the diagnosis and treatment of ASD . The manual updates the methods for assessing language development and the socialization skills of individuals, as well as recognizing restricted and repetitive behavioral patterns.

The diagnosis remains essentially clinical, based on direct observation of the child and interviews with parents and caregivers. The difference is that now the organization also emphasizes the importance of considering environmental, social, and family factors that may cause the manifestation of symptoms associated with autism in neurotypical children, such as delayed language development and difficulties in emotional regulation.

The Brazilian Society of Infectious Diseases (SBNI) recommends that autism screening begin earlier, between 14 and 16 months of age. Conducting a neurological examination has become mandatory to confirm the diagnosis; laboratory and imaging tests should only be requested in specific cases where other conditions are suspected.

These guidelines also advance the recommendation of genetic tests, such as genomic microarray and whole exome sequencing, for a better understanding of the causes and familial risk of the disorder.

The Brazilian Society of Infectious Diseases (SBNI) also advises that the level of support for ASD should not be defined in babies or immediately after diagnosis, as the child's needs may vary during their growth. This classification is made in three levels, which indicate how much support a person with autism may need to carry out their activities.

Someone with level 1 support usually has mild symptoms of the disorder and is able to live more independently. A person with level 3 support may face more difficulty socializing, learning, or performing more complex activities. They may need ongoing support from a family member or caregiver.

Hope for more targeted treatments.

Although autism is not considered a disease, treatment is important to ensure quality of life for those with the disorder. According to Filgueiras, currently, standard treatment involves intensive behavioral and educational interventions, based on the Applied Behavior Analysis (ABA) approach, and other therapies aimed at developing communication, autonomy, sensory integration, and social skills.

From the perspective of pharmacological intervention, there is no single effective treatment for the core symptoms of ASD. "However, advances in understanding the biological mechanisms underlying the disorder are allowing for a more precise stratification of patients, with the identification of subgroups that share specific genetic and molecular profiles," explains the researcher from Einstein.

This differentiation is fundamental to offering more precise genetic counseling to families and enabling the development of more targeted therapeutic approaches. Some completed or ongoing clinical trials are already showing promising results, even if limited to patients with specific clinical conditions.

One example is the studies on leucovorin, an active form of folic acid (vitamin B9, also known as folate). Clinical trials suggest that, when used as a supplement in individuals with ASD who have dysfunctions in the metabolism of this nutrient, it can promote improvements in language, cognition, and behavior.

“However, it is important to emphasize that these effects do not represent a 'cure' for autism, but rather a modulation of symptoms in a subgroup with a well-defined biological profile,” stresses Andréa Sertié. “This type of approach is aligned with the principles of precision medicine, which, instead of seeking generic solutions that disregard the heterogeneity of the disorder, attempts to develop specific interventions targeted at biological and genetic subtypes of ASD.”

This is why the decision by the U.S. Food and Drug Administration (FDA) to revise the labeling of this medication to allow its widespread use in autistic children has recently generated controversy. The product is only approved to treat specific metabolic conditions, such as brain folate deficiency, and to complement care in some chemotherapy protocols.

Cases of autism that present with dysfunctions in the metabolism of this vitamin are few. Therefore, not everyone would benefit from it. "The use of leucovorin should be restricted to well-documented cases of cerebral folate deficiency, with a confirmed diagnosis, and should not be considered a universal treatment for autism," notes Marcela Freitas, from ABN.

Ideally, the management of the disorder should be multidisciplinary, individualized, and continuous, considering each person's abilities, difficulties, and priorities. This may involve the dedication of professionals in speech therapy, occupational therapy, behavioral therapy, psychopedagogy, psychomotor skills, nutrition, and other complementary areas, varying according to need.

“In recent years, medicine has been joining forces with other areas to build ethical, humanized, and participatory approaches. This dialogue has been essential to combat prejudice,” says Freitas. “The current focus is on respecting differences, offering adequate support, and promoting social acceptance, understanding that autism, as well as other neurodevelopmental disorders, represents human diversity.”

Source: Einstein Agency

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