PILLAR PAGE — BRAIN FOG CAUSES
64 Causes of Brain Fog
Evidence-based information. Each cause includes what to do THIS WEEK, what tests to consider, and what has helped others.
Metabolic & Hormonal
9 causes in this category
Thyroid
Your thyroid sets the metabolic speed of every cell — including neurons. The standard TSH-only test misses up to 50% of ...
Menopause
Estrogen is neuroprotective — it drives cerebral blood flow, glucose metabolism, and neurotransmitter synthesis. When es...
Testosterone
Low testosterone impairs cognitive function in both men and women. In men: reduces hippocampal function, impairs spatial...
Cortisol
Chronic stress literally shrinks your hippocampus (memory center) and impairs your prefrontal cortex (focus and decision...
Pmdd
PMDD is not 'bad PMS.' It's a neuropsychiatric condition where normal hormonal fluctuations trigger abnormal brain respo...
Sugar
Blood sugar instability directly impairs cognitive function — both hyperglycemia (glycation damage, inflammatory cascade...
Metabolic Vascular
If you have diagnosed type 2 diabetes, metabolic syndrome, CKD, MASLD/NAFLD, or heart failure — these are PRIMARY medica...
Diabetes
Your brain is a glucose-dependent organ. When blood sugar crashes, your brain starves. The fog hits like a wall — sudden...
Pcos
Insulin resistance + androgen excess + inflammation = cognitive impairment. The fog that comes with hormonal chaos. PCOS...
Gut & Nutrition
10 causes in this category
Histamine
Histamine isn't just allergies — it's a neurotransmitter. When your body produces too much or can't break it down fast e...
Gut
Your gut is your second brain — literally. It produces 95% of serotonin, 50% of dopamine, and houses 70% of your immune ...
Sibo
Small Intestinal Bacterial Overgrowth — bacteria in the wrong place producing gas, toxins, and inflammation that reaches...
Nutrient
Your brain is the most metabolically demanding organ — 20% of your energy budget for 2% of body weight. It cannot make m...
Electrolytes
Your neurons run on electricity — and electricity needs sodium, potassium, magnesium, and calcium in precise balance. El...
Alcohol
Alcohol is directly neurotoxic — even 'moderate' drinking. It disrupts sleep architecture (suppresses REM), depletes B v...
Celiac
The fog that comes with gluten — but 48-72 hours later, not immediately. Your immune system attacks your small intestine...
Anemia
Not enough red blood cells to carry oxygen to your brain. The result: fatigue + fog + pale skin + dizziness + shortness ...
Food Sensitivity
The fog you can't trace. Unlike true allergies (anaphylaxis), food sensitivities cause delayed reactions — 24-72 hours a...
Vitamin D
The fog of the indoors. Low vitamin D = neuroinflammation + reduced neurotransmitter synthesis. Your brain has vitamin D...
Neurological & Structural
6 causes in this category
Neuroinflammation
Your immune system is attacking your brain. Microglia (brain immune cells) stay 'switched on' after infection, autoimmun...
Pcs
Post-concussion syndrome — persistent cognitive symptoms after head injury. The brain injury may have been 'mild' but th...
Cervical
Craniocervical instability (CCI) is the hidden cause that nobody checks for because standard supine MRI misses it. When ...
Hypoperfusion
Your brain uses 20% of your blood supply. Reduced cerebral blood flow (from POTS, blood pressure issues, cervical spine ...
Neurological Red Flags
NOT ALL BRAIN FOG IS BENIGN. This entry exists because some causes of cognitive decline require URGENT medical evaluatio...
Migraine
Migraine is a primary neurological disorder — NOT just a headache. Brain fog during migraine (pre-ictal, ictal, and post...
Sleep & Energy
3 causes in this category
Sleep
Sleep is when your brain cleans itself. The glymphatic system flushes metabolic waste during deep sleep — including the ...
Digital
The average person checks their phone 96 times per day. A landmark 2017 study proved that the mere PRESENCE of your smar...
Sleep Apnea
Your brain is suffocating repeatedly every night. Obstructive Sleep Apnea (OSA) and Upper Airway Resistance Syndrome (UA...
Autoimmune & Infectious
4 causes in this category
Autoimmune
Your immune system is attacking your own tissues — and sometimes your brain. Conditions like lupus, MS, rheumatoid arthr...
Lyme
Lyme disease and co-infections (Bartonella, Babesia, Ehrlichia) can cause persistent neurological symptoms including bra...
Bartonella
Bartonella is the 'stealth infection' — it causes bizarre neuropsychiatric symptoms (rage, anxiety, brain fog, depressio...
Long Covid Mecfs
Post-viral syndromes (Long COVID, ME/CFS, post-EBV, post-Lyme) share a common pattern: your immune system defeated the v...
Connective Tissue & Dysautonomia
3 causes in this category
Pots
POTS is not anxiety. A 2020 JAHA study confirmed measurable cerebral blood flow deficits during standing that directly c...
Eds
Ehlers-Danlos Syndrome (especially hypermobile type) causes brain fog through multiple pathways: craniocervical instabil...
Fibromyalgia
'Fibro-fog' is one of the most debilitating symptoms of fibromyalgia — patients often rate cognitive dysfunction as MORE...
Environmental & Toxic
5 causes in this category
Pesticides
Organophosphates (common agricultural pesticides) are literally designed to be neurotoxins — they kill insects by disrup...
Mercury
WHO states there is no safe level of mercury exposure. Dental amalgam (silver fillings) release mercury vapor continuous...
Mold
Mold exposure in water-damaged buildings can trigger chronic inflammatory responses in genetically susceptible individua...
Air
Indoor and outdoor air pollution directly causes neuroinflammation. PM2.5 particles cross the blood-brain barrier. Carbo...
Meds
Drug-induced cognitive impairment is the most REVERSIBLE cause of brain fog — and the most overlooked. A 2019 JAMA study...
Mental Health & Neurodivergence
5 causes in this category
Adhd
ADHD isn't just 'hyperactive kids' — it's a neurodevelopmental condition affecting executive function, working memory, a...
Autism
Autistic burnout is NOT depression — and treating it with antidepressants alone doesn't work. A 2024 study validated the...
Depression
Depression is not just sadness — it causes measurable cognitive impairment: reduced processing speed, impaired working m...
Social
Humans are social animals — isolation literally shrinks the brain. Loneliness activates the same neuroinflammatory casca...
Psychiatric
NOT ALL COGNITIVE SYMPTOMS ARE 'BRAIN FOG' — some are psychiatric emergencies. Bipolar disorder (manic/depressive episod...
Life Stage & Recovery
3 causes in this category
Chemobrain
Cancer-related cognitive impairment ('chemobrain' or 'chemofog') affects 15-75% of cancer patients and can persist for m...
Post Surgical
Post-surgical cognitive dysfunction is common, underrecognized, and usually temporary — but not always. It affects 10-25...
Postpartum
Postpartum brain fog is a distinct clinical phenomenon driven by the perfect storm: catastrophic sleep deprivation, mass...
Pain
1 causes in this category
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