Autism spectrum disorder (ASD) is a neurodevelopmental condition involving differences in social communication, interaction and behaviour. Researchers are investigating how immune signalling may interact with brain development, although immune differences do not explain every case.
How Does Inflammation Relate to Autism?
The immune system protects against infections and coordinates inflammation. Neuroinflammation refers to inflammatory activity in the brain or central nervous system. Researchers have reported differences in immune activity in some autistic populations, but findings vary across studies [1,2].
Microglia and Cytokines: What Happens in the Brain?
Microglia are immune-related brain cells that help maintain brain tissue and regulate connections between neurons. During development, they participate in synaptic remodelling the process of modifying connections between brain cells.
Cytokines, such as interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α), are proteins that coordinate immune responses. A 2026 systematic review and meta-analysis examined 98 studies involving 4,236 autistic participants and 3,333 non-autistic controls. It found average differences in several cytokines, including IL-6 and TNF-α. However, more than one-third of studies had a high risk of bias, and the findings did not establish a consistent profile or diagnostic test [3].
Maternal Immune Activation and Brain Development
Maternal immune activation occurs when the immune system responds during pregnancy, for example, to an infection. Researchers are investigating how inflammatory signals involving the placenta may influence foetal brain development. Human studies report some associations with autism, but genetic and environmental factors make cause and effect difficult to establish [4].
What Does the Evidence Tell Us?
Immune research may help explain biological differences in some autistic individuals. However, autism is not classified as an immune disorder, and further research is needed before these findings can guide diagnosis or treatment.
Explore our Yodaara for detailed insights into autism and neurodevelopment.
Frequently Asked Questions
Is autism an immune system disorder?
No. Autism is a neurodevelopmental condition, although immune-related differences are being investigated.
How does the immune system affect autism?
Immune signalling may interact with brain development, but its role in autism remains under investigation.
Does inflammation cause autism?
Current evidence does not establish inflammation as a direct cause.
What is maternal immune activation?
It is an immune response during pregnancy that researcher’s study for possible associations with offspring neurodevelopment.
Can infection or fever during pregnancy increase autism risk?
Some studies report associations, but they do not prove that infection or fever directly causes autism.
What role do microglia play in autism?
Microglia help maintain brain tissue and regulate neural connections. Their possible involvement in autism remains under investigation.
Can immune biomarkers detect autism early?
No immune biomarker is currently established as a standalone diagnostic test for autism.
References
- Autism Spectrum Disorder, National Institute of Mental Health.
- Innate immune dysfunction and neuroinflammation in autism spectrum disorder (ASD). Focus. 2024.
- Atypical cytokine profiles in people on the autism spectrum: a comprehensive systematic review and meta-analysis including 54 cytokines. Molecular Psychiatry. 2026.
- Maternal immune activation and autism in offspring: what is the evidence for causation? Biological Psychiatry. 2025.