Unlocking the brain's chemical code: What neurochemistry reveals about autism

By oliviacook // 2025-06-10

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Imbalance in key brain chemicals, like GABA, glutamate and serotonin, may explain common autism symptoms, such as repetitive behaviors, sensory overload and social difficulties.
Dopamine and acetylcholine disruptions contribute to cognitive rigidity, learning challenges and social withdrawal in autism.
Neuropeptides, like melatonin and oxytocin, play important roles in sleep regulation and social bonding, with imbalances potentially worsening common symptoms in autism.
Vitamin D and orexin system dysfunction are linked to early brain development and sleep issues in autism, indicating areas for future research.
Understanding neurochemical imbalances may lead to more personalized treatments and early targeted interventions for children with autism, improving their quality of life.

In a world where roughly one in 36 children is diagnosed with autism spectrum disorder (ASD), scientists are digging deeper than ever into the brain's inner workings to uncover what's behind the condition. While no single cause has been identified, a growing body of research is pointing toward the brain's neurochemical systems – complex networks of molecules that help neurons (brain cells) communicate – as critical pieces of the puzzle. A 2020 comprehensive review published in Brain Sciences examined how imbalances in 12 key neurochemicals may contribute to the development and behavior patterns seen in autism. These neurochemicals – ranging from mood-regulating serotonin to the sleep hormone melatonin – play crucial roles in how the brain processes information, regulates immune and metabolic functions, responds to stimuli and even forms social bonds. When their activity is disrupted, the effects can ripple across brain development and behavior, offering insight into why some children experience the challenges commonly associated with ASD. Autism is a spectrum of developmental differences, meaning that its symptoms vary greatly from person to person. Individuals with ASD may experience language delays, challenges with social interaction, sensory sensitivities and repetitive behaviors, such as obsessive interests or "stimming" (self-stimulation) or repetitive movements like rubbing hands on certain textures or making soothing sounds to calm down, manage anxiety or regulate their senses. While genetics and environmental factors play a role, the neurochemistry of the brain is emerging as a central factor in autism. The brain's chemical "messengers," called neurotransmitters and neuropeptides, help regulate how neurons communicate and influence cognition, mood, social behaviors and more. When these chemicals are out of balance, the brain can struggle to process information effectively, which may help explain the symptoms of ASD.

Key neurochemicals and their roles in autism

Researchers have identified a dozen key neurochemicals and neuropeptides whose imbalances may explain unique behaviors, challenges and strengths seen in individuals with ASD.

GABA and glutamate: The brain's brake and gas pedals

Gamma-aminobutyric acid (GABA) and glutamate are the two primary neurotransmitters responsible for regulating brain activity. GABA acts as an inhibitor, calming down brain activity while glutamate is excitatory, stimulating brain function. In individuals with autism, studies show a disrupted balance between these two chemicals, with an overabundance of glutamate and insufficient GABA. This imbalance can lead to overstimulation, sensory overload and difficulty processing social information, contributing to the behavioral symptoms commonly seen in ASD.

Serotonin: The mood regulator

Serotonin helps regulate appetite, digestion, mood and sleep. In autism, elevated serotonin levels are often found, which may be linked to repetitive behaviors and social difficulties. The altered serotonin system could explain why individuals with autism may engage in behaviors such as obsessive routines and rigid thinking.

Dopamine: Motivation and reward

Dopamine is a neurotransmitter involved in motivation, pleasure and the reward system. It plays a major role in how individuals experience reward and satisfaction. In autism, disruptions in dopamine signaling may contribute to symptoms like a lack of motivation to engage in social interactions and social withdrawal, as well as repetitive behaviors. These disruptions could make social connections less rewarding and more challenging to navigate.

Acetylcholine: Memory and learning

Acetylcholine is crucial for attention, learning and memory. In individuals with ASD, reduced levels of acetylcholine receptors in the brain may hinder the ability to focus or learn effectively and cognitive flexibility. This could contribute to difficulties with attention, learning new tasks and processing information.

N-acetyl aspartate (NAA): Brain energy and function

N-acetyl aspartate (NAA) is a compound found in neurons that serves as a marker for brain energy and metabolic health. Lower levels of NAA in the brains of individuals with autism suggest that brain cells may not be functioning at optimal levels, possibly reflecting developmental issues or energy shortages in central brain regions.

Oxytocin and arginine-vasopressin: Social bonding

Oxytocin, often called the "love hormone," plays a key role in empathy, social bonding and trust. Similarly, arginine-vasopressin helps regulate emotional responses and social behavior. Studies have shown that individuals with ASD often have altered levels of oxytocin and vasopressin, which could explain the difficulties many people with autism face when it comes to forming social connections and reading emotional cues and building relationships.

Melatonin: Sleep regulation

Melatonin is the hormone responsible for regulating the sleep-wake cycle. Many individuals with autism experience significant sleep disturbances and research has shown that they tend to have lower melatonin levels. This deficiency can make it harder for individuals to fall asleep or stay asleep, leading to exhaustion and further exacerbating other symptoms of autism, such as inattention or irritability.

Vitamin D: More than just bone health

Vitamin D is essential for bone health, but its role extends to the brain, where it influences neurotransmitter production and immune system regulation. Some studies suggest that children with autism may have lower vitamin D levels, which could potentially impact brain development. Supplementing with vitamin D has shown some promise in improving certain ASD-related symptoms, though results vary across individuals.

The orexin system: Arousal and sleep

The orexin system is involved in regulating appetite, arousal and wakefulness. In autism, some research has found disruptions in this system, particularly concerning sleep disturbances. An overactive orexin system, paired with insufficient serotonin and melatonin activity, may contribute to chronic sleep issues seen in autism.

Endogenous opioids: Pain and emotional regulation

Endogenous opioids are the body's natural painkillers, also involved in regulating emotional responses and mood. In individuals with autism, elevated levels of endogenous opioids have been observed, particularly in response to pain or stress. These changes could explain the differences in how people with autism perceive pain or process emotional experiences. Some therapeutic trials using opioid blockers have shown modest improvements in hyperactivity and irritability.

Why this research matters

The findings from this study offer valuable insights for families and clinicians looking to better understand autism and explore more personalized treatment options. By identifying the specific neurochemical imbalances that may underlie many of the symptoms of ASD, researchers hope to pave the way for new, targeted interventions. (Related: Nut are brain food: Study reveals consuming nuts during pregnancy may help improve brain development in children.) For parents and caregivers, this research provides a deeper understanding of how autism affects the brain, offering hope for better treatments and earlier interventions, including diets. As more is learned about these neurochemical imbalances, it could lead to therapies tailored to an individual's unique brain chemistry, improving their overall quality of life. Ultimately, while much remains to be discovered about the neurochemical underpinnings of autism, these breakthroughs bring us closer to a future where treatments are more effective, personalized and truly responsive to the needs of individuals on the spectrum. Get updates on brain research on autism by watching this video. This video is from the Daily Videos channel on Brighteon.com.

Sources include:

PMC.NCBI.NLM.NIH.gov Brighteon.com