I have spent decades learning about how bodies and brains work, but nothing has taught me more about complexity than raising my autistic son. He is nine, curious, brilliant, and completely captivated by chemistry. He can explain the structure of an atom with more clarity than most high school students.

But when we step into the real world (classrooms, stores, even family gatherings), sometimes his brain does not get to shine. Instead, it floods.

• The lights are too bright.
• The voices too many.
• The expectations too fast.
• The interruptions too constant.
• The world, too much.

The science that helped me understand

The brain develops by refining its connections, strengthening the ones that matter, and letting go of the ones that do not. This process, called synaptic pruning, is essential for building efficient, focused neural networks. It is especially active during early childhood and adolescence, when the brain is wiring itself for life.

But in autism, this pruning process may not work the way it should. Research shows that the autistic brain tends to retain too many synaptic connections, resulting in hyperconnectivity. That might sound beneficial, but it often means that everything comes in at once. Sounds, lights, textures, emotions; there is no filter, no way to quiet the noise. His brain is constantly processing more than it should have to.

A 2025 study published in Molecular Psychiatry brought this picture into even sharper focus. Since directly studying the brain’s microglia (the immune cells responsible for pruning synapses) is difficult in living humans, researchers turned to their biological cousins: macrophages, immune cells derived from the blood. They used growth factors to “train” these macrophages into two types: one more inflammatory, and one more regulatory, similar to how microglia behave in the brain.

The scientists then exposed these macrophages to synaptosomes (fragments of synaptic connections) to assess their ability to perform phagocytosis, the process of engulfing and removing cellular material. In neurotypical individuals, the regulatory-type macrophages (M-CSF-induced) showed high levels of synaptosome phagocytosis. But in individuals with autism, those same macrophages demonstrated a significant reduction in phagocytic capacity.

Even more compelling was the link to a gene called CD209. This gene helps immune cells recognize what needs to be cleared out. In the macrophages from autistic individuals, CD209 expression was significantly lower, meaning their cells could not recognize the synaptic material that needed to be eliminated. As a result, synaptic fragments were left behind, unpruned.

This was the first study to show impaired synaptosome phagocytosis in human immune cells outside the brain; and it helped explain what I see in my son every day. His overwhelm is not just emotional. It is biological. His brain is not just sensitive; it is flooded with input that it cannot organize or eliminate.

The stress bucket: a metaphor that fits

To explain this to others, and sometimes to myself, I turn to the Stress Bucket Model.

• The bucket represents a person’s capacity to manage stress and sensory input.
• Water gets added every time something stressful or stimulating happens — noise, transitions, hunger, confusion, being misunderstood.
• Neurotypical people often have a larger drain, so the bucket empties easily.
• But for autistic individuals, that drain is often smaller, and it takes far less to reach overflow.

When the bucket gets too full, it spills. The result might look like a meltdown, a panic attack, or sudden silence. But it is not about that one event; it is about everything that came before. It is the accumulation that overwhelms.

What hurts, and what helps

Here is what fills his bucket quickly:

• Too many people talking at once
• Harsh lights
• Too many changes in his routine
• Being pulled away from his passions (like chemistry)
• Being misunderstood, or not having time to speak
• Being told to sit still when he needs to move

And here is what helps empty it, what helps regulate him:

• Slowing things down, including my voice
• Dimming the lights
• Removing unnecessary demands
• Breathing techniques
• Ice packs to his wrist
• Time with his Rubik’s Cube — something to solve, focus, and move with
• Hugging his big stuffy, “Charlie” — a donut-shaped, comforting, constant presence
• Reading his favorite book on propulsion science
• Moving freely, stimming
• Being near someone calm who listens without judgment

Slowing down is our medicine

When I see the signs (shallow breathing, clenched fists, tensing his body), I do not correct. I do not escalate. I pause. I soften my voice. I lower the lights. I let go of expectations. I make space, not just physically, but neurologically. Space for his brain to stop defending itself and just be.

And when we slow the world down, he can finally return to himself. Sometimes, it only takes a few moments of stillness. Sometimes it takes hours. But that quiet space is where his brilliance lives.

What I hope others will remember

This is not about giving in. This is not about bad behavior. This is about biology.

When we understand how the autistic brain processes too much, too intensely, and too fast, we stop expecting it to respond like a neurotypical one. We stop assuming the child is being difficult when they are really overloaded. We start looking behind the behavior. We start accommodating, not correcting. Supporting, not scolding.

Autistic children are not fragile. But they are often flooded. And the world can be harsh on a brain that is already working overtime.

What I know as a mom

My son does not need to be “toughened up” for the world. The world needs to turn down the volume (just a little) so he can think clearly, move freely, and share the remarkable ideas already inside him. Sometimes, his brain does not get to shine. Instead, it floods. But when we slow everything down, even just for a moment, it shines again.

Carrie Friedman is a dual board-certified psychiatric and family nurse practitioner and the founder of Brain Garden Psychiatry in California. She integrates evidence-based psychopharmacology with functional and integrative psychiatry, emphasizing root-cause approaches that connect neuro-nutrition and gut–brain science, metabolic psychiatry, immunology, endocrinology, and mind–body lifestyle medicine. Carrie’s clinical focus bridges conventional psychiatry with holistic strategies to support mental health through nutrition, physiology, and sustainable lifestyle interventions. Her professional writing explores topics such as functional medicine, autism, provider well-being, and medical ethics.