How Inflammation and the Immune System Drive Long-COVID Brain Damage

Last updated: October 2025

The Hidden Impact of Long-COVID on the Brain

Most people think of COVID-19 as a respiratory illness, but scientists now know the virus can profoundly affect the brain. For many, recovery from COVID doesn’t end their symptoms. Weeks or months later, they may struggle with memory problems, poor concentration, fatigue, or emotional changes—collectively known as “long-COVID.”

These symptoms often arise because the immune system remains overactive after the infection ends. When this happens, chronic inflammation disrupts the brain’s chemical balance and damages neurons. At The Carroll Institute, we’ve found that understanding and treating this inflammatory response is the key to restoring brain health after COVID.

How Inflammation Affects Brain Function

Inflammation is part of the body’s defense mechanism. Normally, it helps fight infections and repair tissues. However, when inflammation becomes chronic, it causes lasting harm.

In the brain, chronic inflammation interferes with how neurons communicate and damages the protective myelin sheath around nerve fibers. Over time, this leads to slower processing speed, brain fog, and cognitive decline. Studies published in Nature and The Lancet Psychiatry show that even mild infections can lead to measurable gray-matter loss in regions tied to memory and decision-making. In other words, COVID doesn’t just make you tired—it can actually change your brain’s structure.

The Immune System’s Role in Post-COVID Brain Injury

During infection, the immune system releases cytokines—proteins that help fight viruses. But when cytokines stay elevated too long, they can create a “cytokine storm.” This flood of inflammatory chemicals crosses the blood–brain barrier, damages brain cells, and disrupts neural communication.

COVID can also activate microglia, the brain’s immune cells. When overactivated, these cells attack healthy neurons as if they were foreign invaders. This ongoing state of inflammation prevents the brain from healing and rebuilding connections, which explains why some people experience symptoms for months—even when no active virus remains.

Why Chronic Inflammation Damages Memory and Focus

Inflammation affects multiple brain regions, including the hippocampus (memory formation) and the prefrontal cortex (attention and executive function). This is why many post-COVID patients feel foggy, forgetful, or unable to focus on complex tasks.

In severe cases, long-COVID inflammation may accelerate the same processes seen in Alzheimer’s disease. Elevated inflammatory markers such as IL-6 and TNF-alpha—commonly found in post-COVID patients—are also linked to cognitive decline in aging. Addressing inflammation early helps break this cycle and protects long-term brain health.

How We Address Post-COVID Brain Inflammation

Traditional medicine often offers little beyond symptom management. Many are told to “wait it out.” Unfortunately, time alone rarely heals brain inflammation. At The Carroll Institute, Dr. Garland Glenn combines the ReCODE Program with Functional Neurology to reverse post-COVID cognitive decline by targeting root causes and rebuilding function.

Step 1: Comprehensive Testing

• Inflammatory markers (CRP, IL-6, TNF-alpha)
• Hormone and nutrient panels (thyroid, cortisol, vitamin D, B vitamins)
• Insulin resistance and blood sugar markers (fasting insulin, HbA1c, HOMA-IR)
• Mycotoxin and heavy metal screening
• Genetics (e.g., APOE and detox pathways) when appropriate
• Functional Neurology assessments to identify affected brain circuits

Step 2: Calm the Immune System and Reduce Inflammation

Treatment begins with anti-inflammatory nutrition, targeted supplementation, gut support, and detoxification where needed. We also optimize sleep and stress regulation, because both strongly influence inflammatory signaling.

Step 3: Rebuild Brain Pathways with Functional Neurology

Reducing inflammation is only half the solution. To truly heal, the brain must be retrained. Using customized neurological exercises, we stimulate specific underperforming regions and reconnect disrupted networks. This includes visual tracking, balance and coordination work, and sensory–motor integration drills tailored to the individual.

We frequently incorporate photobiomodulation therapy (red/near-infrared light to support blood flow and cellular energy) and neurosensory motor integration tools to accelerate neuroplasticity—the brain’s ability to form new connections.

Step 4: Support Neuroplasticity for Long-Term Recovery

As inflammation settles, consistent, targeted drills strengthen new neural pathways. Over time, patients report clearer thinking, better focus, improved mood, and renewed energy—signs that the brain is truly recovering, not just compensating.

Why This Matters: The Overlap with Alzheimer’s Biology

Post-COVID neuroinflammation shares biological pathways with early cognitive decline: oxidative stress, impaired glucose metabolism, and mitochondrial dysfunction. By addressing these factors with a multi-factor plan—root cause testing, metabolic optimization, detoxification, and brain-specific rehabilitation—we protect cognition now and reduce future risk.

“Inflammation may start the problem, but neuroplasticity finishes the healing. The brain is remarkably resilient when given the right support.”

— Dr. Garland Glenn

References

• Douaud G. et al. SARS-CoV-2 is associated with changes in brain structure. Nature, 2022.
• Taquet M. et al. Six-month neurological and psychiatric outcomes in COVID-19 survivors. The Lancet Psychiatry, 2022.
• Bredesen DE, et al. Sustained Cognitive Improvement in Alzheimer’s Disease Patients Following a Precision Medicine Program. Biomedicines, 2024.

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Medically reviewed by: Dr. Garland Glenn, DC, PhD, AFMC (Advanced Functional Medicine Clinician)

The Carroll Institute — Sarasota, FL

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Educational content only; not a substitute for personalized medical advice.