Functional Neurology Explains Why Concussion Symptoms Spiral

One of the most frustrating experiences for people with persistent post-concussion syndrome is being told:

And yet, they still can't tolerate busy environments. They still get dizzy in grocery stores. They still struggle with headaches, brain fog, light sensitivity, fatigue, anxiety, and cognitive overload — and it's not getting better with time.

If everything is normal, why do they still feel broken? Dr. Matt Antonucci and Dr. Kenneth Jay published a paper in the scientific journal Frontiers in Systems Neuroscience (Jan 2026) that outlines a model to explain this exact question.

The Problem With Traditional Models

Modern neurology excels at identifying structural problems — tumors, strokes, hemorrhages, multiple sclerosis. These conditions produce visible changes on imaging. But what about the millions of people whose symptoms are clearly neurological, yet whose imaging appears normal?

Dr. Antonucci estimates that as many as 1.3 billion people worldwide may fall into this gap — individuals with neurological dysfunction that cannot be adequately explained by structural imaging alone. This includes many people with concussion, migraine, ADHD, autism, dysautonomia, persistent dizziness, and sensory processing disorders.

Functional neurology attempts to bridge this gap by focusing not only on brain structure, but on how neural networks function.

The Brain Is a Network, Not a Collection of Parts

Traditional neuroanatomy often teaches the brain in isolated regions. The frontal lobe does executive function. The occipital lobe processes vision. But this doesn't reflect how the brain actually works. The brain functions more like a network — every experience depends upon communication between multiple regions simultaneously.

When those networks become disrupted, symptoms emerge — even when the structures themselves remain intact.

Why Concussion Symptoms Can Spiral

Dr. Antonucci describes concussion as a disorder of maladaptive feedback loops. The brain receives sensory information, processes it, generates a response, and receives feedback about that response. When the brain is functioning normally, this cycle allows for constant adjustment and optimization.

After a concussion, however, the processing may become distorted. Normal sensory information can produce abnormal outputs. Those abnormal outputs generate abnormal feedback. The abnormal feedback is then fed back into the system, creating a self-reinforcing cycle. Over time, the nervous system can become trapped in these loops, causing symptoms to intensify, spread, and become increasingly complex.

Neuroplasticity Is Not Always Your Friend

Most discussions of neuroplasticity are overwhelmingly positive — and often, that's true. But neuroplasticity itself is neutral. The brain will strengthen whatever pathways are repeatedly used. That can be beneficial. It can also reinforce dysfunctional patterns.

Dr. Antonucci compares this process to an airport closure. If one route becomes unavailable, traffic gets rerouted elsewhere. Initially, this adaptation is helpful. But over time, the alternative route becomes the new normal. The original pathway weakens, while compensatory pathways become deeply entrenched. This may help explain why some patients develop chronic symptoms long after the initial injury has resolved.

Why Grocery Stores Are So Difficult

Many concussion patients describe a common experience: "I'm fine at home. But the moment I go into a grocery store, everything falls apart."

This is where the concept of load becomes extremely important. When demands on the nervous system increase, hidden vulnerabilities become exposed. Bright lights, crowded aisles, moving people, visual complexity, decision-making, background noise — all of these increase processing demands. A nervous system operating near capacity may appear functional under minimal load but begin to fail when demands increase.

A New Way to Think About Recovery

"The nervous system does not descend into chaos. It reorganizes into new, often less efficient but stable configurations."

That sentence may fundamentally change how we think about persistent post-concussion syndrome. Patients are not broken. Their brains are adapting. The problem is that the adaptations may no longer be serving them.

Recovery may not require simply reducing symptoms. It may require helping the nervous system reorganize itself again — this time toward more efficient and resilient patterns.

The Future of Functional Neurology

The NERD model is still a theoretical framework, but Dr. Antonucci and his colleagues have already completed a randomized controlled trial comparing the model against standard concussion care, with publication expected soon. If validated, this work could represent an important step toward a more comprehensive understanding of concussion, neuroplasticity, and functional neurological disorders.

More importantly, it offers something many patients desperately need: a framework that explains why symptoms persist — and a roadmap for how recovery may still be possible. I'm honored to call Dr. Antonucci one of my mentors and teachers, and his work has greatly influenced how I approach patient care in my clinic.