Solving the AUTISM puzzle: Link between the immune system and brain health

07/01/2025 / By Olivia Cook

Research suggests that immune system dysfunction or imbalances, inflammation and maternal health during pregnancy may influence brain development and increase autism risk.
Cytokines, the body’s immune messengers, help regulate inflammation. An imbalance in these signals may disrupt neural connections, potentially contributing to autism.
Maternal obesity can lead to chronic inflammation, which might affect fetal brain development. Certain fats in the diet may also influence immune responses linked to autism.
The link between autism and other brain disorders like Parkinson’s disease: Though different in age and symptoms, both conditions show immune-related brain inflammation and genetic factors that affect brain function.
Understanding how immune responses impact the brain could lead to novel therapies, including anti-inflammatory approaches and dietary interventions.

For decades, researchers have been trying to understand and explain the complex nature of autism spectrum disorder (ASD). What makes some children more susceptible to neurodevelopmental conditions affecting behavior, communication and social interaction? Studies suggest that inflammation, immune system imbalances and even maternal health during pregnancy are key factors in shaping the developing brain.

A recent study published March 2022 in the International Journal of Molecular Sciences dives deep into this connection. But for the everyday reader, the scientific language can be overwhelming. Let’s break it down in a way that makes sense.

Cytokines and why they matter

Think of cytokines as the body’s tiny chemical messengers that help immune cells communicate. Some messages say, “Hey, we need backup!” when the body is fighting an infection. Others say, “All clear, stand down.” When these messages get scrambled – either too many are sent or the wrong ones are delivered – immune system dysfunction can occur. Scientists have found that many children with autism have an unusual balance of cytokines, suggesting that their immune systems may be out of sync.

Immune system’s role in brain development

Your immune system is not just for fighting off germs – it also plays a role in brain development. During pregnancy, a mother’s immune system influences how the baby’s brain forms. If the mother experiences infection or chronic inflammation and develops obesity, these conditions impact the baby’s neurodevelopment. Researchers believe that when the immune system is overactive, it can interfere with the normal formation of neural connections, potentially increasing the risk of autism.

One of the key players in this process is microglia, the brain’s immune cells. Imagine microglia as the brain’s “clean-up crew;” they are responsible for removing unnecessary connections between brain cells and ensuring everything is running smoothly. But if they become overactive – triggered by inflammation or immune responses – this “clean-up” process could disrupt essential neural pathways.

Link between obesity, inflammation and autism

Obesity is often considered a physical health issue, but it can also affect the brain. Excess body fat is not just stored energy – it actively releases inflammatory molecules. This creates a chronic state of low-grade inflammation, sometimes called “meta-inflammation.” If a mother is obese during pregnancy, her body’s inflammatory state might alter fetal brain development. Researchers are investigating whether this long-term inflammation could contribute to autism.

Adding to this, certain fats in a mother’s diet – like saturated fatty acids – can activate immune pathways that lead to inflammation. This means that diet, obesity and the immune system are all interconnected, potentially influencing how the brain develops before birth. (Related: Rethinking autism: How maternal health during pregnancy influences a child’s autism risk.)

Autism and Parkinson’s disease

At first glance, autism and Parkinson’s disease seem like two completely different conditions – one affecting children’s cognitive and social skills, the other primarily seen in older adults with movement difficulties. But scientists have found surprising similarities between the two.

Both conditions show signs of neuroinflammation, meaning the immune system is actively involved in brain dysfunction. In Parkinson’s, certain brain cells that produce dopamine (a chemical important for movement) are damaged, often due to an overactive immune response. In autism, the affected brain regions are different, but the common thread is an immune system that might be disrupting normal brain function.

Another interesting overlap is genetics. Some genes play a role in autism – especially those affecting synapses (the connection between brain cells) – and are also linked to Parkinson’s. This suggests that immune system dysfunction may be a shared factor in both conditions, even though they manifest in different ways.

Role of the MHC and HLA genes

The immune system is finely tuned to recognize threats, and a key part of this system is the major histocompatibility complex (MHC). In humans, these genes are known as human leukocyte antigens (HLA). They help the immune system distinguish between the body’s own cells and foreign invaders. Recent research suggests that certain variations in the HLA genes may increase susceptibility to both autism and neurodegenerative diseases, hinting at a deeper connection between immunity and brain function.

Adaptive vs innate immunity

The immune system has two main branches: innate immunity, which provides the first line of defense, and adaptive immunity, which is more specialized and remembers past infections. Scientists have reason to believe that both systems are involved in autism.

Overactive innate immune responses – such as excessive inflammation – could disrupt brain development, while adaptive immunity differences might alter how the brain reacts to environmental factors.

T helper (Th) cells, a key component of adaptive immunity, help regulate immune responses. Imbalances in Th cell activity have been found in children with autism, suggesting that their immune systems may be wired differently from birth.

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Watch the following video about immunological issues in individuals with autism.

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