– What causes autism?
— Researchers have explored numerous theories about how autism begins. Early ideas suggested a defect in a particular brain region or the way the two hemispheres connect. It became clear over time that no single brain abnormality explains autism. Instead, autism is understood as an umbrella term for a range of conditions that produce similar signs. This is why many professionals use the term autism spectrum disorder, or ASD, rather than autism alone.
— Could different children with ASD have different brain development paths?
– Yes. ASD is a highly heterogeneous developmental condition. Many distinct factors can lead to similar outcomes—challenges in social communication, unusual patterns of behavior, and repetitive actions. Think of a fever: it has many possible causes but often a single set of symptoms. In ASD, the shared symptom is a disruption in behavior and communication, not a fever.
— It seems there is no single brain difference that distinguishes children with ASD from their typically developing peers.
— If a child with autism undergoes an MRI, it will often show no specific pathology. There are cases where anomalies are visible, but most often the macrostructure of the brain appears typical. The underlying issues may involve neural connections or circuits that MRI does not reveal clearly.
— Do scientists know which brain functions become disrupted to cause ASD?
— The prevailing neurophysiological theory points to an imbalance in certain nerve cell types. Excitatory and inhibitory neurons regulate brain activity, and a proper balance is essential for development and daily functioning. In autism each person differs from typical development in unique ways, and no two individuals show the exact same pattern.
— How are researchers studying this balance without invasive approaches?
— In animal models, invasive methods can measure this balance, but they cannot be used in humans. Noninvasive techniques are needed. Studies have looked at young children with ASD and peers without ASD using magnetic encephalography, or MEG. The MEG device available in the country offers a noninvasive way to map brain activity and compare patterns related to the excitatory inhibitory balance in ASD, providing a broader view of brain function without entering the skull.
— What advantages does MEG provide?
— MEG can localize sources of brain activity with notable precision. It helps researchers track activity changes thought to reflect an imbalance in brain signaling in children with ASD. While it does not show every neuron, MEG offers a window into the overall neural environment and how it relates to behavior.
The findings show a shift toward higher arousal in autism mainly among children with lower cognitive ability. This aligns with the higher incidence of epilepsy in more severe autism cases, often accompanied by intellectual disability.
— What does the direction of the excitation and inhibition change mean for diagnosis and treatment?
— The pattern could serve as a biomarker to support diagnosis and tailor treatments. By testing how a drug affects neural balance, clinicians could monitor changes before and after therapy. Yet it is important to interpret results cautiously and rely on multiple studies before drawing firm conclusions.
— Are genes the main driver of ASD?
– Genetic factors account for a large portion of ASD risk, estimated around 70 to 90 percent in many cases. Hundreds of genes have been linked to autism to varying degrees, influencing neural networks tied to social behavior and communication. Some genes are active even before birth, during early brain development, shaping how neurons form and connect.
— Do autism genes come more from one parent than the other?
— The scientific literature does not show a simple parent-of-origin pattern for most autism genes. The risk generally arises from a combination of inherited contributions from both parents. In a few forms, such as certain fragile site disorders, one parent may play a larger role.
— Could autism genes be present but not activated?
– Definitely. Many people carry genes associated with autism, and ASD develops when a specific set of these genes is activated or suppressed in a particular combination. Environmental factors also contribute and can interact with a genetic predisposition to raise the chance of ASD when present with other risks.
However, environmental influences matter too. Premature birth, certain medications during pregnancy, or infections can increase risk, especially when combined with a genetic predisposition.
— What about auditory and speech difficulties in autism? Why do these occur and which brain areas are involved?
— Speech delay is often one of the first non-specific signs of autism. Most children with ASD begin speaking after age three, and language difficulties can affect phonology, syntax, semantics, and pragmatics. About 30 percent of children with ASD speak very little or not at all.
Two main ideas describe these speech challenges. First, social and communicative difficulties may reduce motivation to engage in speech. Second, some children may have trouble processing complex auditory signals, which can hamper language processing even if hearing is normal by standard tests.
— Which sound processing problems are common in ASD?
– Sound information travels from the cochlea through brainstem and thalamic stations to the cortex. Speech perception difficulties can arise at one or more stages of this path. A child might hear normally on routine tests but struggle to extract meaningful information from what is heard, especially in noisy settings.
This auditory processing difficulty can affect learning and communication. It is important to examine these disorders because some forms can be improved with training. Current studies explore how the brains of children with ASD process vowels and their role in speech understanding.
— Why focus on vowels?
— Vowels mark the earliest stage of speech development and are key for understanding spoken language. In experiments, children watched silent cartoons while listening to vowel sounds, altered vowels, and control sounds. Neurotypical children quickly differentiated vowels from background noise, while children with autism showed reduced responses to vowels. Early results also show correlations with behavioral assessments, though they are preliminary.
— How does this relate to behavior?
— The weaker brain response to vowels often coincides with poorer perception of speech amid noise. Many individuals with ASD experience significant difficulty following conversations in noisy environments, a challenge sometimes described as a cocktail party effect. Purely behavioral studies show children with ASD struggle to assemble spoken words into cohesive meaning when background noise is present, regardless of cognitive level. They may repeat fragments without forming complete sentences.
— What might cause this issue with attention switching?
— One hypothesis points to reduced efficiency of the attention-switching system. In studies where startling sounds were introduced, children with ASD showed a dampened response, especially in the right hemisphere, a region important for shifting attention. The right hemisphere also supports social processing, and impairments here may contribute to social communication difficulties. More research is needed to clarify these links, as drawing definitive conclusions remains challenging.
— Can these auditory-speech problems be corrected?
— There are two main approaches. The first is listening training with interactive software or game-like programs. The second uses remote microphone systems where a microphone near the speaker’s mouth amplifies the voice for the child. This technology can be integrated into hearing aids or headphones to improve speech clarity. Studies suggest such devices can also help children with dyslexia who experience auditory processing issues. Long-term use may promote lasting changes in brain function, supporting ongoing benefits beyond device use.
— Is this method used in Russia?
— These techniques are not yet widespread in Russia. Ongoing studies at a university center and its MEG facility investigate home systems with external microphones and the neural mechanisms behind auditory-speech disorders in children with ASD. The goal is to translate findings into practical benefits for families.
— What if parents want to participate in research?
— Researchers welcome interested families to learn about ongoing studies and how participation might contribute to improving quality of life for children with ASD. Participation decisions are voluntary and guided by ethical oversight.