Lyme disease patients have described brain fog for decades. When COVID-19 emerged, millions of new patients began reporting the same symptoms — slowed thinking, memory lapses, word-finding problems, and mental fatigue that persisted long after the acute infection resolved.
The overlap is striking. And it’s not a coincidence.
Both conditions appear to trigger neuroinflammation and immune dysregulation that disrupts how the brain processes information. Understanding why COVID-19 brain fog and Lyme brain fog look so similar may help validate what Lyme patients have been saying for years — and open new avenues for treatment.
What Does COVID-19 Brain Fog Look Like?
Dr. Aluko Hope from Montefiore Hospital in New York City described what he learned from listening to COVID-19 patients: about a third reported they could no longer recall telephone numbers they used to know, struggled to find the right word, or couldn’t remember where they left their keys.
Dr. Adam Kaplan, a neuropsychiatrist at Johns Hopkins University, observed a similar pattern. Patients described slower thinking, difficulty picking up information in conversation, short-term memory problems, and an inability to multitask. Some struggled to return to work or school.
These descriptions are virtually indistinguishable from what Lyme disease patients report.
What Causes COVID-19 Brain Fog?
The exact mechanisms are still being studied, but contributing factors may include nerve damage, changes in blood flow to the brain, anxiety and depression, post-traumatic stress, and the effects of medications used during hospitalization. However, brain fog also occurs in patients who were never hospitalized.
The most compelling explanation focuses on the immune response. Joanna Hellmuth, a neurologist at the UC San Francisco Memory and Aging Center, suggests that prolonged immune activation after COVID-19 may be creating cognitive changes — something about the ongoing activation of the immune system appears to impair brain function.
This mechanism — persistent immune activation driving cognitive symptoms — is the same pattern described in cytokine-driven brain fog in Lyme disease.
Brain Fog Often Follows Infections
Marie Grill, a neurologist at the Mayo Clinic, noted that brain fog following infection is well established. It occurs after Lyme disease, Epstein-Barr virus, and other infections. As she put it, many neurologists are not surprised to see this pattern with COVID-19 because they have seen it many times before.
For Lyme disease patients, this acknowledgment matters. It confirms that post-infectious cognitive symptoms are a recognized medical phenomenon — not a psychological invention. The COVID-19 pandemic brought mainstream attention to a pattern that Lyme patients have experienced and reported for decades.
Why COVID-19 Brain Fog and Lyme Brain Fog Look the Same
Both conditions can trigger elevated cytokines in the central nervous system, microglial activation and sustained neuroinflammation, disruption of the blood-brain barrier, altered cerebral blood flow, autonomic nervous system dysfunction, and sleep disruption and fatigue that worsen cognitive symptoms.
The cognitive symptoms are driven by the inflammatory response rather than by the specific pathogen. This explains why brain fog from COVID-19 and brain fog from Lyme disease present so similarly — the downstream effects on the brain are the same.
What Lyme Patients Already Knew
Long before COVID-19, Lyme disease patients described persistent brain fog after treatment. Many were told their symptoms were psychological, stress-related, or impossible given their test results. The emergence of Long COVID — with identical cognitive complaints — has helped legitimize what Lyme patients have been saying all along.
Can COVID-19 Brain Fog Improve?
Scientists don’t yet know how long cognitive changes will last in COVID-19 patients or whether they will have lasting effects on brain function. However, the experience of Lyme disease patients suggests that improvement is possible — particularly when neuroinflammation, sleep disruption, autonomic dysfunction, and immune activation are addressed.
Recovery from post-infectious brain fog tends to be gradual and nonlinear.
Clinical Takeaways
COVID-19 brain fog and Lyme brain fog present with strikingly similar symptoms due to shared mechanisms of neuroinflammation, immune dysregulation, and autonomic dysfunction. Both conditions trigger elevated cytokines, microglial activation, and disruption of the blood-brain barrier, explaining why cognitive symptoms appear nearly identical despite different pathogens. The COVID-19 pandemic has validated what Lyme patients reported for decades — that post-infectious brain fog is documented, measurable, and potentially treatable rather than psychological in origin.
Frequently Asked Questions
Is COVID-19 brain fog the same as Lyme brain fog?
The symptoms are strikingly similar. Both are likely driven by neuroinflammation and immune dysregulation rather than direct brain infection, resulting in nearly identical cognitive complaints.
Can you have both COVID-19 and Lyme brain fog?
Yes. Patients with both infections may experience compounded cognitive symptoms. Each condition should be evaluated and treated independently.
Does brain fog after infection mean permanent damage?
Not typically. Post-infectious brain fog usually reflects functional disruption rather than structural injury. Many patients experience gradual improvement when neuroinflammation, sleep, and immune activation are addressed.
Related Reading
- Long COVID and Lyme Disease: What Patients Need to Know
- Cytokine Brain Fog: How Inflammation Affects Thinking in Lyme
- Cognitive Dysfunction in Lyme Disease
- Changes in Smell in COVID-19 and Lyme Disease
- COVID-19 Long-Haulers and Lyme Disease Patients Share Similar Frustrations
- Don’t Forget About Lyme Disease in the COVID-19 Pandemic
References
- Harrison S. Confused About Covid Brain Fog? Doctors Have Questions, Too. Wired. November 6, 2020.
