Why the Neurodivergent Brain May Be Stuck in Inflammation Mode

When we talk about ADHD and autism, the conversation almost always centers on neurotransmitters. Dopamine. Serotonin. The usual suspects. But there is another system that research is increasingly pointing toward, one that operates underneath neurotransmitter activity and shapes the very architecture of how the brain develops and functions.

That system is neuroinflammation. And the cells at the center of it are called microglia. This post is not a simple story. But it is an important one, both for parents trying to understand what is happening in their child's brain, and for women with ADHD who have been told their symptoms are purely chemical.

What Microglia Actually Do

Microglia are the brain's resident immune cells. They make up roughly 10 to 15 percent of all cells in the central nervous system, and for a long time they were largely overlooked. Neuroscience focused on neurons. Microglia were considered support staff.

That view has changed significantly.

Microglia are now understood to be active participants in how the brain is built and maintained. During development, they do something remarkable: they prune synapses. Synaptic pruning is the process by which the brain eliminates excess neural connections to refine and optimize its circuitry. Think of it like editing a rough draft. Too many connections create noise. Pruning creates clarity.

Microglia also release molecules that support synapse formation, regulate neural circuit development, and respond to environmental threats. When something triggers an immune response in the brain, infection, inflammation, oxidative stress, microglia shift from a resting surveillance state into an activated, reactive state. In that activated state they release proinflammatory cytokines including TNF-alpha, IL-6, and IL-1beta (Petrelli et al., 2016).

In the short term, this activation is protective. In the context of chronic or early-life neuroinflammation, it becomes a problem.

What Happens When Microglia Stay Activated

The brains of individuals with autism spectrum disorder show consistent evidence of altered microglial and astrocyte function. Post-mortem brain tissue studies have found increased reactive gliosis and glial cell proliferation. PET imaging studies have documented microglial activation in multiple brain regions of young adults with ASD, including the cerebellum, midbrain, and frontal cortical areas. High levels of proinflammatory cytokines, TNF-alpha, IL-6, and IL-1beta, have been found in both post-mortem brain tissue and in the blood of autistic individuals (Petrelli et al., 2016).

What does this mean clinically? When microglia remain in a chronically activated state, their normal functions become disrupted. Synaptic pruning, which requires precise, regulated microglial activity, may become dysregulated. Some synapses that should be retained get eliminated. Some that should be refined remain. The result is altered connectivity, not random damage.

Astrocytes, the other major glial cell type, are equally implicated. Astrocytes contact up to 100,000 synapses each and release neuroactive substances that influence synapse formation and function. When chronic neuroinflammation shifts astrocytes into a reactive state, their ability to support normal synaptic architecture is compromised (Petrelli et al., 2016).

This is not a neurotransmitter problem at its root. It is a neuroimmune problem that affects neurotransmitter systems downstream.

The ADHD Connection

The neuroinflammation story is not limited to autism. Emerging research is building a similar case for ADHD.

Prenatal exposure to inflammation has been associated with changes in offspring brain development, including reductions in cortical gray matter volume in areas relevant to ADHD. The evidence includes elevated inflammatory markers in ADHD, comorbidity between ADHD

and autoimmune conditions, polymorphisms in inflammation-related genes, and mechanistic animal model data showing that maternal immune activation produces behavioral and neural outcomes consistent with ADHD pathophysiology (Patel, 2023).

Activated microglia release proinflammatory cytokines that have been shown in animal studies to produce neurotransmission changes similar to those seen in ADHD, specifically increased norepinephrine and reduced dopamine (Verlaet et al., 2017). This means neuroinflammation does not just coexist with ADHD neurotransmitter dysregulation. It may actively drive it.

For women with ADHD, there is an additional layer. Research in animal models has found sex-dependent associations between microglial inflammation and behavioral outcomes, with inflammatory microglial activity showing distinct patterns in females compared to males. The ADHD research base has been shaped largely by male subjects. The neuroimmune picture in women may look meaningfully different.

Why This Runs in Families

Neuroinflammation helps explain something that genetics alone does not fully account for: why neurodivergence clusters in families across diagnostic categories.

A parent with ADHD is more likely to have a child with ADHD — but also more likely to have a child with ASD, anxiety, or learning differences. The diagnostic categories are different. The underlying biological systems are often shared.

Genetics plays a role. So does shared neuroimmune architecture. Immune regulation patterns, inflammatory tone, and microglial sensitivity have heritable components. When the same family carries tendencies toward heightened immune reactivity or altered microglial function, those tendencies can express differently across individuals — as ADHD in one person, ASD in another, sensory processing differences in a third.

This is not a defect being passed down. It is a biological pattern expressing itself across a spectrum of variation.

What Can Drive Neuroinflammation

Understanding that neuroinflammation is part of the picture opens up a different set of clinical questions than how do we fix the dopamine.

Gut health matters significantly. The gut-brain axis directly influences microglial activation state. Gut dysbiosis and increased intestinal permeability are associated with elevated systemic inflammatory markers that can shift microglia toward a proinflammatory state.

Nutrient status matters. Zinc, omega-3 fatty acids, magnesium, and vitamin D all play roles in regulating inflammatory signaling. Deficiencies in these nutrients are common in neurodivergent populations and are clinically relevant to neuroinflammatory tone.

Chronic stress matters. The HPA axis and immune system are deeply interconnected. Chronic stress activates inflammatory pathways, and for people whose microglia may already be sensitized, that activation has downstream consequences on mood, focus, and regulation.

Sleep matters. Sleep disruption increases inflammatory cytokine production and impairs the brain's overnight clearance of metabolic waste. Inadequate sleep is both a symptom and a driver of neuroinflammatory burden in neurodivergent individuals.

What This Means for the Clinical Picture

None of this means medication is wrong. Stimulant medications work for many people with ADHD and addressing dopamine dysregulation directly is clinically legitimate.

But if neuroinflammation is part of what is driving or sustaining symptoms, in a child with ASD, in a woman with ADHD whose symptoms worsen dramatically each luteal phase, in a family where neurodivergence has clustered across generations, then addressing only the neurotransmitter layer leaves the deeper picture untouched.

This is why functional medicine approaches to neurodivergence look at gut health, nutrient status, inflammatory markers, sleep, and stress physiology alongside behavioral symptoms. Not instead of the diagnosis. Alongside it.

The brain is not separate from the body. Microglia respond to what is happening systemically. And what is happening systemically can be assessed, understood, and supported.

Microglia are the brain's immune and maintenance cells. In neurodivergent brains, consistent evidence points to altered microglial and astrocyte function — a state of chronic or sensitized neuroinflammation that affects synapse development, neural circuit organization, and neurotransmitter signaling. This pattern is documented in ASD and increasingly implicated in ADHD. It helps explain why neurodivergence clusters in families across diagnostic categories and why symptoms in some individuals extend far beyond what neurotransmitter models alone can account for.

The neuroimmune picture is not a replacement for the genetic or neurotransmitter story. It is a third layer and for many people, it is the layer that has been missing from the conversation.

Want to Explore What This Looks Like in Your Picture?

This is the kind of layered, systems-based assessment I do inside my 3-Month Functional Lab Package. We look at gut health, inflammation markers, nutrient status, and the interconnected systems shaping how your brain and body are actually functioning — not just what shows up on a standard panel.

References

Patel, S. (2023). A potential role for neuroinflammation in ADHD. In Y. K. Kim (Ed.), Neuroinflammation, gut-brain axis and immunity in neuropsychiatric disorders. Advances in experimental medicine and biology (Vol. 1411). Springer. https://doi.org/10.1007/978-981-19-7376-5_15

Petrelli, F., Pucci, L., & Bezzi, P. (2016). Astrocytes and microglia and their potential link with autism spectrum disorders. Frontiers in Cellular Neuroscience, 10, 21. https://doi.org/10.3389/fncel.2016.0002

Rodríguez-Martínez, E., & Martínez-Moreno, A. (2022). Enhanced glial reaction and altered neuronal nitric oxide synthase are implicated in attention deficit hyperactivity disorder. Frontiers in Cell and Developmental Biology, 10, 901093. https://doi.org/10.3389/fcell.2022.901093

Verlaet, A. A. J., Noriega, D. B., Hermans, N., & Savelkoul, H. F. J. (2017). Attention-deficit/hyperactivity disorder and inflammation: What does current knowledge tell us? A systematic review. Frontiers in Psychiatry, 8, 228. https://doi.org/10.3389/fpsyt.2017.00228