Does Lyme Disease Contribute to Dementia?
Last Updated: December 2025
Dr. Jessica Knape of HealthSpan Internal Medicine in Boulder, CO, explains how Lyme disease can affect brain function long after the initial infection. She highlights that while Lyme does not directly cause dementia, chronic inflammation and immune disruption from persistent Lyme can mimic or accelerate the same pathways involved in cognitive decline, leading to brain fog, memory issues, and mood changes.
Lyme disease is best known for causing fatigue, joint pain, and rash.
But for many people, especially when infection goes unrecognized or incompletely treated, the symptoms go far deeper — affecting focus, mood, and memory.
At HealthSpan Internal Medicine in Boulder, CO, we often see patients struggling with brain fog, confusion, or word-finding difficulty months or even years after a tick bite.
These symptoms raise an important question: can Lyme disease — or its persistent inflammation — increase the risk of dementia?
The short answer: yes, indirectly. While Lyme disease does not cause Alzheimer’s or other dementias outright, chronic infection and immune dysregulation can mimic, amplify, or accelerate the same inflammatory and metabolic pathways seen in neurodegeneration.
HealthSpan Insight
Lyme disease can trigger chronic neuroinflammation, oxidative stress, and vascular dysfunction — all risk factors for dementia.
“Lyme brain” symptoms can overlap with mild cognitive impairment (MCI), depression, or early Alzheimer’s.
Treating underlying infection and restoring mitochondrial and immune balance can significantly improve clarity and cognition.
1. What Is Lyme Disease?
Lyme disease is caused by the bacterium Borrelia burgdorferi, transmitted through tick bites.
While early symptoms often include rash, fever, and fatigue, the infection can persist and affect multiple systems, including the nervous system (neuroborreliosis).
The brain and spinal cord are particularly vulnerable because Borrelia can:
Cross the blood–brain barrier,
Trigger immune activation and microglial inflammation, and
Persist in tissues long after initial infection.
These immune and vascular changes can resemble processes seen in Alzheimer’s and other dementias.
2. How Lyme Disease Affects the Brain
When Borrelia reaches the nervous system, the immune response can become chronic.
Even after bacterial levels decline, neuroinflammation may persist — a condition sometimes referred to as post-treatment Lyme disease syndrome (PTLDS).
In the brain, this inflammation:
Disrupts neuron signaling and blood flow
Increases oxidative stress and cytokines (like TNF-α, IL-6)
Lowers mitochondrial energy production
Alters neurotransmitters like dopamine and serotonin
The result is a mix of cognitive and emotional symptoms:
Short-term memory lapses
Poor concentration or multitasking
Word-finding difficulty
Fatigue or apathy
Anxiety, depression, or irritability
3. The Link Between Lyme and Dementia Risk
While Lyme disease does not directly cause Alzheimer’s, studies show a concerning overlap in biological patterns:
A. Chronic Inflammation
Long-term immune activation from Lyme can increase systemic inflammation — the same inflammation that drives neurodegenerative diseases.
B. Microglial Activation
Microglia are the brain’s immune cells. In Lyme and dementia, they can stay “stuck” in a reactive state, damaging nearby neurons.
C. Vascular Dysfunction
Lyme can affect small blood vessels, reducing oxygen and nutrient flow — a mechanism also central to vascular dementia.
D. Biofilms and Persistent Infection
Borrelia can hide in biofilms (protective microbial communities), making eradication difficult and perpetuating oxidative stress.
E. Immune Cross-Reactivity
Some antibodies produced during chronic infection may mistakenly target brain tissue — an autoimmune mechanism that can contribute to neurodegeneration.
4. “Lyme Brain” vs. Dementia: How to Tell the Difference
While Lyme-related cognitive impairment can look like dementia, there are key distinctions:
Onset
Lyme-Related Cognitive Impairment: Often sudden or post-infectious
Alzheimer’s/Dementia: Gradual, progressiveSymptoms
Lyme-Related Cognitive Impairment: Brain fog, word-finding issues, fatigue
Alzheimer’s/Dementia: Memory loss, orientation problemsMood
Lyme-Related Cognitive Impairment: Irritability, anxiety, depression
Alzheimer’s/Dementia: Apathy or emotional bluntingResponse to Treatment
Lyme-Related Cognitive Impairment: Improves with infection and inflammation control
Alzheimer’s/Dementia: Slower progression, partial responseAge Group
Lyme-Related Cognitive Impairment: Can occur in younger adults
Alzheimer’s/Dementia: Typically older adults
A full evaluation helps distinguish between active neuroinflammation and degenerative change.
5. Testing and Diagnosis
At HealthSpan, our diagnostic approach integrates both infectious and metabolic perspectives.
Testing may include:
Comprehensive Lyme panels (ELISA, Western blot, C6 peptide, or advanced T-cell assays)
Co-infection testing (Bartonella, Babesia, Ehrlichia, Mycoplasma)
Inflammatory and metabolic markers (CRP, cytokines, ferritin, homocysteine)
Cognitive screening (MoCA or CNS Vital Signs)
Brain imaging, if needed, to rule out structural or vascular causes
We also evaluate sleep, oxygenation, and methylation, since these often worsen cognitive inflammation.
6. Treatment: Addressing Infection and Inflammation
Lyme-related cognitive symptoms often improve once the underlying infection and immune response are addressed.
An integrative plan may include:
A. Antimicrobial Therapy
Appropriate antibiotics (or herbal antimicrobials, depending on chronicity and sensitivity) to target persistent infection.
B. Anti-Inflammatory Support
Omega-3 fatty acids
Curcumin, resveratrol, or green tea polyphenols
Low-dose naltrexone (LDN) for immune modulation
C. Mitochondrial and Nutrient Repletion
CoQ10, acetyl-L-carnitine, alpha-lipoic acid
B vitamins (especially B12, folate, and B6)
Magnesium and antioxidants
D. Detox and Gut Repair
Supporting the liver and microbiome helps reduce circulating toxins and neuroinflammatory load.
E. Lifestyle Medicine
Gentle movement and aerobic exercise
Restorative sleep hygiene
Mindfulness and breathwork to regulate the vagus nerve
7. When Lyme Unmasks Underlying Dementia
In some patients, Lyme infection may unmask early neurodegenerative disease that was already developing silently.
This happens because infection adds inflammatory “load” to a vulnerable system.
When inflammation is reduced, these patients often stabilize — highlighting how treating Lyme can slow cognitive decline even when Alzheimer’s pathology exists.
8. The Role of the Immune System and Autoimmunity
A growing body of research shows that Lyme disease can trigger autoimmune encephalitis, where the immune system mistakenly attacks brain tissue.
This process can mimic rapid-onset dementia or psychiatric illness.
In such cases, treatment may include anti-inflammatory or immunomodulatory therapies (like LDN or IVIG) alongside antimicrobial care.
Early recognition is key: the sooner neuroinflammation is calmed, the better the recovery.
9. Preventing Cognitive Decline After Lyme
You can reduce long-term brain risk by supporting the systems most affected:
Methylation and detoxification (B12, folate, NAC, glutathione)
Mitochondrial repair (CoQ10, carnitine, NAD+)
Gut-brain axis (probiotics, fiber, anti-inflammatory diet)
Cerebral circulation (exercise, hydration, nitric oxide support)
Stress resilience and sleep (mindfulness, yoga, breath training)
These steps help the brain restore balance and reduce ongoing inflammation — protecting both memory and mood.
Bottom Line
Lyme disease doesn’t directly cause dementia — but chronic inflammation, vascular injury, and immune activation from persistent infection can contribute to the same biological pathways that drive cognitive decline.
If you’ve had Lyme disease and notice changes in memory, concentration, or mood, it’s important to test, treat, and repair early.
By calming inflammation, restoring energy metabolism, and rebuilding neural resilience, the brain can heal — often remarkably well.
At HealthSpan Internal Medicine, we integrate infectious disease management with functional brain care to help patients recover from “Lyme brain” and reduce their lifetime risk of dementia.
Schedule a Brain & Nutritional Optimization Evaluation with Dr. Knape to assess your cognitive symptoms, rule out metabolic or inflammatory contributors, and develop a personalized plan to support brain health, memory, and long‑term neurological resilience.
Sources
Lack of Convincing Evidence That Lyme Disease Causes Alzheimer’s or Lewy Body Dementia - PubMed
Neuropsychiatric Manifestations of Lyme Disease: Psychiatric & Cognitive Impacts - PMC
Medically reviewed by
Dr. Jessica Knape, MD, MA Board Certified in Internal Medicine and Integrative and Holistic Medicine
Healthspan Internal Medicine — serving patients in Boulder, CO
Book a Discovery Call | About Dr. Knape
This content is for educational purposes and does not replace personalized medical advice.
