Article library
Brain fog articles
Start with what you notice: when it appears, what changes it, or what your tests haven't explained.
Three guides before you start narrowing it down
What Does Brain Fog Feel Like?
Slower thinking, poor recall, word-finding trouble, and the spaced-out feeling people struggle to describe. Start here if you can't put the feeling into words yet.
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Is Brain Fog a Sign of Something Serious? A Red-Flag Guide
When to worry, when to wait, and the specific red flags that mean you should see a doctor this week, not next month.
Brain Fog After Normal Tests: Prepare for Your Visit
Bring your full test reports, note when the change began, and describe two or three examples from daily life. Use those details to prepare for your next appointment.
Original reporting and personal investigation
Editor's picks
Three pieces we wrote after investigating the questions ourselves.
Cat Scratch Brain Fog: What the Bartonella Evidence Does and Does Not Show
This article revisits a personal investigation. Cat and flea contact belongs in your medical history, the evidence on Bartonella's mental effects is thin, and a negative test plus lasting brain fog doesn't justify treatment.
Read the articleYour Ferritin Is 'Normal' at 15. Your Brain Disagrees.
Optimal vs lab-normal ferritin, iron transport to the brain, and why women under 50 are most likely to have technically-normal iron that is functionally inadequate.
Read the articleI Stand on One Foot Every Morning. A Study of 1,702 People Explains Why.
A 10-second balance test predicted death risk better than most bloodwork. It tests your brain, not your legs. Here's what it has to do with brain fog.
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Start Here
3 articles
Start Here
3 articlesThese three guides help you describe brain fog, recognize warning signs and prepare for an appointment after normal tests.
What Does Brain Fog Feel Like?
Slower thinking, poor recall, word-finding trouble, and the spaced-out feeling people struggle to describe. Start here if you can't put the feeling into words yet.
Is Brain Fog a Sign of Something Serious? A Red-Flag Guide
When to worry, when to wait, and the specific red flags that mean you should see a doctor this week, not next month.
Brain Fog After Normal Tests: Prepare for Your Visit
Bring your full test reports, note when the change began, and describe two or three examples from daily life. Use those details to prepare for your next appointment.
Gut and Digestion
7 articles
Gut and Digestion
7 articlesBrain fog after meals, bloating, food reactions, and how bacterial overgrowth links digestion to the brain through the vagus nerve and inflammation.
Why Does Gut Dysbiosis Cause Brain Fog? The 90-Minute Post-Meal Timeline
The vagus nerve, bacterial metabolites, and intestinal permeability. How gut symptoms, meal-linked crashes, and inflammation overlap with cognition problems.
Brain Fog After Eating: Is It Blood Sugar, Histamine, SIBO, or Something Else?
Comparing causes of post-meal brain fog. Timing, food type, and accompanying symptoms point toward different causes.
GERD and Brain Fog: Can Acid Reflux Cause Brain Fog?
This article looks at medications, reflux that disrupts sleep, and vagus nerve irritation. It also shows what sets reflux apart from similar gut and anxiety causes.
Can Your Reflux Medication Cause Brain Fog? The PPI-SIBO Connection
PPIs double SIBO risk, a 2025 meta-analysis found. How acid-suppressing medications may create the bacterial overgrowth that causes brain fog.
SIBO vs IBS Brain Fog: How to Tell the Difference
38% SIBO prevalence in IBS patients. How to tell SIBO from functional gut problems when both cause post-meal brain fog.
SIBO and Histamine Intolerance: Is There a Link to Brain Fog?
Dysbiosis found in 66% of histamine intolerance patients. How gut bacteria produce histamine and why antihistamines alone don't fix the problem.
SIBO and Blood Sugar: How Diabetes Affects the Gut and What to Check
The diabetes-SIBO cycle: how gastroparesis feeds bacterial overgrowth, and how overgrowth worsens glucose control and cognition.
Hormones and Metabolism
3 articles
Hormones and Metabolism
3 articlesThyroid, cortisol, estrogen, and blood sugar. In each, lab values sit in the "normal" range while the brain runs low on energy.
Cortisol and Brain Fog: When Testing Helps
What cortisol tests check, which symptoms to record and what supplement research shows.
Diabetic Brain Fog: Blood Sugar, Cognition & Recovery
Glucose variability damages small blood vessels in the brain. Post-meal crashes, HbA1c results, and what continuous glucose monitors show.
Ozempic Brain Fog: The Paradox Nobody Is Explaining
GLP-1 agonists may protect your brain long-term while starving it short-term. A 2026 review found ferritin 26-30% lower than on another diabetes drug. What's actually causing the brain fog and what to do about it.
Immune and Inflammatory
4 articles
Immune and Inflammatory
4 articlesNeuroinflammation, mast cell activation, histamine, and post-viral immune dysfunction. Brain fog that feels pressured, flu-like, or reactive.
Neuroinflammation and Brain Fog: Why Your Brain Feels Inflamed (and What Helps)
Microglial activation, cytokine storms, blood-brain barrier permeability. An explainer for brain fog that feels pressured, flu-like, or post-viral.
MCAS Brain Fog: Mast Cell Activation and Cognition
Why food reactivity, flushing, itching, headaches, and post-meal brain fog overlap. Histamine in the brain acts as a neurotransmitter, not just an allergen.
Food Allergies & Brain Fog: The 72-Hour IgG Connection
How congestion, sleep disruption, histamine burden, and seasonal reactivity blur thinking. The delayed immune response that standard allergy tests miss.
Long COVID Symptoms Do Not Follow One Script
Post-viral, autonomic, inflammatory, and exertional problems overlap and don't point to one neat label. How to untangle them.
Infections
2 articles
Infections
2 articlesBacterial and tick-borne infections that hide inside cells and evade standard testing. Chronic infections produce neuroinflammation that looks like everything else.
Cat Scratch Brain Fog: What the Bartonella Evidence Does and Does Not Show
This article revisits a personal investigation. Cat and flea contact belongs in your medical history, the evidence on Bartonella's mental effects is thin, and a negative test plus lasting brain fog doesn't justify treatment.
Lyme Brain Fog Won't Clear After Antibiotics: What's Actually Happening
This article covers post-treatment Lyme, the debate over lingering infection, and brain inflammation. It also shows what makes a tick-borne cause more or less likely.
Brain and Nervous System
5 articles
Brain and Nervous System
5 articlesADHD overlap, anxiety mimics, post-concussion symptoms, and autonomic dysfunction. These causes get misdiagnosed as each other more often than they get diagnosed correctly.
Concussion Brain Fog: The Energy Crisis in Your Head
Structural, balance, sensory, and overload problems after head injury. Why post-concussion brain fog follows its own rules.
POTS Brain Fog: Why Standing Crashes Your Cognition
Positional brain fog, standing intolerance, blood pooling, and what sets standing-related problems apart from other fatigue and dizziness.
EEG and Brain Fog: What Brain Waves Reveal
When EEG is useful, what it actually measures, and why most brain fog needs broader tests than a single brain scan.
Weed and Brain Fog: The Honest Guide Nobody Else Will Write
CB1 receptor downregulation, working memory effects, dose-response curves, and the recovery timeline after quitting. No moralizing.
There is a hormone you have probably never heard of called Irisin
A muscle-released hormone (irisin) and adaptive cognitive challenge both raise BDNF, the brain's build-and-repair protein. The 2026 ACTIVE follow-up cut 20-year dementia risk by 25% with the right training, done in a specific way.
Sleep and Breathing
1 article
Sleep and Breathing
1 articleSleep architecture, glymphatic clearance, and airway obstruction. You can sleep eight hours and still deprive your brain of restorative rest.
Nutrients and Testing
3 articles
Nutrients and Testing
3 articlesThe labs your doctor didn't run, the reference ranges that hide deficiency, and the self-tests you can do at home before your next appointment.
Your Ferritin Is 'Normal' at 15. Your Brain Disagrees.
Optimal vs lab-normal ferritin, iron transport to the brain, and why women under 50 are most likely to have technically-normal iron that is functionally inadequate.
Brain Fog Tests to Ask Your Doctor: The Labs Nobody Runs (and What 'Normal' Is Hiding)
The extended panel beyond CBC and TSH. Ferritin, vitamin D 25-OH, fasting insulin, homocysteine, CRP, and what each one actually tells you.
I Stand on One Foot Every Morning. A Study of 1,702 People Explains Why.
A 10-second balance test predicted death risk better than most bloodwork. It tests your brain, not your legs. Here's what it has to do with brain fog.
Substances and Habits
1 article
Substances and Habits
1 articleCaffeine, nicotine, cannabis, and inactivity. Low-risk experiments you can run in 1-2 weeks to test whether a habit is contributing.
Using this library
How should I use this article library?
Start with the three orientation guides if you are not sure what your symptoms mean yet. Otherwise, filter the library or open the topic closest to what changes your symptoms.
Why are the articles organized by body system?
The groups make a large library easier to scan. They are starting points, not diagnoses. Related topics remain linked when symptoms may have more than one explanation.