Microglia in the cerebral cortex in autism.

Scientists looked at donated brain tissue from people with autism and matched controls. They counted microglia, the brain’s immune cells, in two areas: front-insular and visual cortex.

They used special stains and microscopes to get exact cell counts. The goal was to see if autism brains hold more microglia than typical brains.

Autism brains had clearly higher microglial density in both regions studied. The rise was large enough to be seen without complex stats.

More microglia means ongoing immune activity, not just development noise.

Spriggs et al. (2015) extends this picture by showing the same brains also carry more GFAP, a sign of active astrocytes, in nearby white matter. Together, two types of glia look stirred up.

Matson et al. (2011) used the same post-mortem autism cortex but counted regular neurons and found normal numbers. This keeps the spotlight on glia, not overall cell loss.

Oblak et al. (2013) and Weiss et al. (2001) mapped neurotransmitter receptors in similar tissue and saw drops in serotonin and GABA markers. Microglia rises plus receptor drops hint at parallel immune and chemical changes.

You can’t count microglia during a clinic visit, but knowing they are elevated gives you a talking point with families. Explain that immune markers, not just behavior, differ in autism. When you see co-occurring autoimmune issues or unusual regression, consider a medical referral. Keep an eye on future blood or PET tests that might track microglia; they could become useful bio-markers or treatment targets.