View Featured Categories
What Causes Brain Fog? Researchers Are Looking Beyond Aging
Brain Health · Cognitive Function
Have you ever walked into a room and forgotten why you went there? Or struggled to find a familiar word even though you know you know it? Many people describe experiences like these as brain fog.
Brain fog is not a medical diagnosis. It's a general term for problems with concentration, memory, mental processing, word-finding, and mental clarity. While some changes in thinking are a normal part of aging, brain fog can have many other causes — including poor sleep, stress, medications, illness, nutritional deficiencies, and hormonal changes.
Normal Aging and the Brain
Normal aging can bring some changes in memory and thinking. Older adults may take longer to learn something new, recall information, or process complex information. Occasional forgetfulness, such as briefly forgetting a name or misplacing something, can also be normal.(1) Normal aging does not mean losing the ability to function independently — dementia is not a normal part of aging.(1)
Slower Processing
It may take longer to understand or respond to information.
Occasional Forgetfulness
You may forget a name or why you entered a room but remember later.
Word-Finding Difficulty
A familiar word may be temporarily difficult to retrieve.
More Difficulty Multitasking
Dividing attention between several tasks may become harder.
Slower Learning
New information may require more repetition, although the ability to learn remains.
Changes in Sleep
Sleep changes with age can contribute to daytime fatigue and reduced attention.
The Role of NAD+ in Aging
As we age, cellular nicotinamide adenine dinucleotide (NAD+) declines. NAD+ is a coenzyme that influences many metabolic pathways — from DNA repair to immune cell function — and plays a role in maintaining metabolic health and healthy aging. Restoring these levels through supplementation has been beneficial in restoring and relieving age-related diseases.(2)
PQQ: For Both Age-Related Decline and Brain Fog
PQQ (pyrroloquinoline quinone) is a micronutrient supplement often used to combat brain fog. In a double-blind, placebo-controlled study in which PQQ was administered to adults aged 40–65 over 12 weeks, participants experienced improved cognitive and verbal memory.(3)
Methylene Blue: Century-Old Medicine Shows Promise
Methylene blue is a 100-year-old medicine that shows promise in reducing oxidative stress, treating memory loss, and neurodegeneration. It can cross the blood-brain barrier, where it can enable mitochondria (the workhorses of the cell) to work more efficiently. Because of its antioxidant and neurogenerative abilities, methylene blue could be an asset for both age-related decline and brain fog.(4)
That combination of effects is part of why comprehensive cognitive-support formulas — such as RECHARGE, which pairs methylene blue with NAD and PQQ — are designed to address mitochondrial health, cellular renewal, and oxidative stress together rather than targeting just one piece of the picture.
Brain Fog Is Not Simply "Getting Older"
Brain fog often feels different from ordinary age-related forgetfulness. The problem may be more about attention and mental processing than permanent memory loss. People often describe it the same way: "I know I know this, but I can't access it right now." Brain fog can happen at any age, and several factors can contribute to it.
Brain Fog May Involve
- Difficulty concentrating
- Losing your train of thought
- Trouble finding familiar words
- Slower thinking
- Short-term memory problems
- Difficulty making decisions
- Mental fatigue
- Feeling mentally "cloudy"
Poor Sleep
Sleep is essential for attention, memory, and other mental functions. Even one night of restricted sleep can increase sleepiness and impair sustained attention.(2) Sleep quality matters, too — someone can spend eight hours in bed but still experience brain fog if sleep is repeatedly interrupted by insomnia, stress, pain, snoring, sleep apnea, illness, alcohol, or an irregular schedule.
Poor Sleep Can Affect
- Concentration
- Working memory
- Processing speed
- Decision-making
- Motivation and energy
Stress
Stress can also make thinking feel cloudy. The body's stress response changes brain systems involved in attention, working memory, decision-making, and emotional regulation.(6, 7)
Stress Can Cause Brain Fog By
- Constantly worrying, which takes attention away from other tasks
- Disrupting working memory: you may lose your train of thought or forget what you were doing
- Interfering with sleep: stress can make it harder to fall asleep or stay asleep
- Changing executive function: prolonged stress can interfere with the brain's ability to plan, focus, and manage multiple demands(6, 7)
Medications
Some medications can cause drowsiness, slowed thinking, confusion, or memory problems. This is particularly important in older adults when several medications are taken together.
Medication Groups That Can Affect Cognition
- Benzodiazepines, such as alprazolam, diazepam, and lorazepam
- First-generation antihistamines, such as diphenhydramine (Benadryl), commonly given or used for insomnia
- Certain sleep medications, including some benzodiazepine-related drugs
- Opioid pain medications, which can cause sedation and slowed thinking
- Anticholinergic medications, which interfere with acetylcholine, a chemical messenger important for attention and memory(8, 9)
The total medication burden can matter as much as an individual drug. Research has found associations between higher anticholinergic medication exposure and cognitive impairment, particularly among older adults.(8) If brain fog begins after starting a medication or changing its dose, discuss the timing with a healthcare professional. Do not stop prescription medications suddenly without medical guidance.
Illness and Inflammation
Illness can cause temporary brain fog, and some people experience cognitive symptoms after an illness has been resolved. When the immune system responds to infection or other threats, it releases inflammatory signaling molecules called cytokines. These signals can communicate with the brain and contribute to what researchers call "sickness behavior," which can include fatigue, sleep changes, reduced motivation, and cognitive difficulties.(10) Brain fog during illness usually has multiple possible contributors, not just inflammation — it's usually transient and can resolve after illness.
Illness Can Also Cause Brain Fog Through
- Poor sleep from pain, fever, coughing, or congestion
- Physical fatigue
- Dehydration
- Eating less than usual
- Changes in blood sugar
- Medications used to treat symptoms
One notable exception is infection or vaccination with SARS-CoV-2. The spike protein of SARS-CoV-2 has been documented to stay in the body and can cause brain fog for at least 3.5 years.(11,12)
Nutritional Deficiencies
The brain needs adequate nutrients to maintain nerve cells and produce energy. Certain deficiencies can cause neurological symptoms, fatigue, or concentration problems — and not eating enough food or becoming dehydrated can cause fatigue and poor concentration even without a specific vitamin deficiency.
Nutrients Linked to Cognitive Symptoms
- Vitamin B12: deficiency can cause fatigue, confusion, poor memory, and neurological problems such as numbness and tingling(13)
- Iron: iron-deficiency anemia can cause tiredness and problems with concentration and memory(14)
- Thiamine (vitamin B1): significant deficiency can cause confusion and short-term memory problems and, in severe cases, serious neurological disease(15)
- Folate and other B-vitamin deficiencies: can affect nervous system function and neurological development(16)
Hormonal Changes
Hormones influence sleep, mood, energy, attention, and memory. Changes in hormone levels can affect how mentally sharp someone feels.
Perimenopause & Menopause
Cognitive complaints are common. Some women experience changes in verbal learning and memory, processing speed, attention, or working memory during the transition. Sleep problems, hot flashes, and stress may also contribute.(17)
Thyroid Hormones
Thyroid hormones influence metabolism and nervous system function. Hypothyroidism can be associated with fatigue and memory problems.(18)
Other Autoimmune Diseases
Lupus, type 1 diabetes, fibromyalgia, and other autoimmune diseases can cause brain fog.(19)
Stress Hormones
Cortisol, a valuable stress hormone when your body needs it, can go into overdrive during times of excessive stress. Chronic stress can affect sleep and brain functions involved in attention and memory.(6, 7)
When Should Brain Fog Be Checked?
Not every instance of forgetfulness is cause for concern. However, evaluate cognitive changes if they are new, ongoing, worsening over time, or beginning to interfere with daily activities.
Talk With a Healthcare Professional If Cognitive Problems Affect
- Finances
- Medication management
- Driving (getting lost or confused)
- Work or school
- Cooking or other familiar tasks
- Daily independence
It's also important to get evaluated if family members notice a significant change in your thinking or behavior. The National Institute on Aging notes that repeatedly asking the same questions, getting lost in familiar places, having trouble following directions, or becoming increasingly confused about time, people, or places can be signs that a person should be evaluated.(1)
It May Not Be Just Aging
Brain fog should not automatically be blamed on aging. The most useful question may not be "Is this just aging?" Instead, ask: "Is this a normal change for me, or could something treatable be affecting how my brain is functioning?" That shift in framing is what separates a passive assumption from an answer worth pursuing.
Featured Product
RECHARGE / Cognitive Support
Methylene Blue, Reimagined
RECHARGE is the first-ever combination of methylene blue, NAD, and PQQ — the same three compounds discussed above — formulated to support mental clarity, mitochondrial health, and cellular renewal.*
Shop NowYou Might Also Be Interested In
References
- National Institute on Aging. (2023, November 22). Memory problems, forgetfulness, and aging. National Institutes of Health.
- Strømland Ø, Diab J, Ferrario E, Sverkeli LJ, Ziegler M. The balance between NAD+ biosynthesis and consumption in ageing. Mech Ageing Dev. 2021 Oct;199:111569. doi: 10.1016/j.mad.2021.111569. Epub 2021 Sep 9. PMID: 34509469.
- Tamakoshi M, Suzuki T, Nishihara E, Nakamura S, Ikemoto K. Pyrroloquinoline quinone disodium salt improves brain function in both younger and older adults. Food Funct. 2023;14(5):2496–2501. https://doi.org/10.1039/d2fo01515c
- Xue H, Thaivalappil A, Cao K. The Potentials of Methylene Blue as an Anti-Aging Drug. Cells. 2021 Dec 1;10(12):3379. doi: 10.3390/cells10123379. PMID: 34943887; PMCID: PMC8699482.
- Deboer, T. (2018). Sleep and cognitive performance. Sleep Medicine Clinics, 13(2), 157–167.
- Girotti, M., Adler, S. M., Bulin, S. E., Fucich, E. A., Paredes, D., & Morilak, D. A. (2018). Prefrontal cortex executive processes affected by stress in health and disease. Progress in Neuro-Psychopharmacology and Biological Psychiatry, 85, 33–39.
- Arnsten, A. F. T. (2009). Stress signalling pathways that impair prefrontal cortex structure and function. Nature Reviews Neuroscience, 10, 410–422.
- Chatterjee, S., Talwar, A., & Aparasu, R. R. (2020). Anticholinergic medications and risk of dementia in older adults: Where are we now? Expert Opinion on Drug Safety, 19(10), 1251–1267.
- Liu, L., Jia, L., Jian, P., Zhou, Y., Zhou, J., Wu, F., & Tang, Y. (2020). The effects of benzodiazepine use and abuse on cognition in the elders: A systematic review and meta-analysis of comparative studies. Frontiers in Psychiatry, 11, 00755.
- Dantzer, R., O'Connor, J. C., Freund, G. G., Johnson, R. W., & Kelley, K. W. (2008). From inflammation to sickness and depression: When the immune system subjugates the brain. Nature Reviews Neuroscience, 9(1), 46–56.
- Hulscher, N., Schmidt, V., Mörz, M., Rogers, C., von Ranke, N., Zhang, W., Catanzaro, J. A., & McCullough, P. A. (2026). Unprecedented persistence of vaccine mRNA, plasmid DNA, spike protein, and genomic dysregulation over 3.5 years post-COVID-19 mRNA vaccination [Preprint]. Zenodo. https://doi.org/10.5281/zenodo.18460099
- Hulscher N, Procter BC, Wynn C, McCullough PA. Clinical Approach to Post-acute Sequelae After COVID-19 Infection and Vaccination. Cureus. 2023 Nov 21;15(11):e49204. doi: 10.7759/cureus.49204. PMID: 38024037; PMCID: PMC10663976.
- National Institutes of Health, Office of Dietary Supplements. (2025). Vitamin B12: Fact sheet for health professionals.
- National Institutes of Health, Office of Dietary Supplements. (2025). Iron: Fact sheet for health professionals.
- National Institutes of Health, Office of Dietary Supplements. (2022). Thiamin: Fact sheet for health professionals.
- Kronenberg G, Harms C, Sobol RW, Cardozo-Pelaez F, Linhart H, Winter B, Balkaya M, Gertz K, Gay SB, Cox D, Eckart S, Ahmadi M, Juckel G, Kempermann G, Hellweg R, Sohr R, Hörtnagl H, Wilson SH, Jaenisch R, Endres M. Folate deficiency induces neurodegeneration and brain dysfunction in mice lacking uracil DNA glycosylase. J Neurosci. 2008 Jul 9;28(28):7219-30. doi: 10.1523/JNEUROSCI.0940-08.2008. PMID: 18614692; PMCID: PMC3844834.
- Metcalf, C. A., Duffy, K. A., Page, C. E., & Novick, A. M. (2023). Cognitive problems in perimenopause: A review of recent evidence. Current Psychiatry Reports, 25(10), 501–511.
- National Institute of Diabetes and Digestive and Kidney Diseases. (2024). Hashimoto's disease. National Institutes of Health.
- Cleveland Clinic. (2022, June 14). Strategies for busting up brain fog.
Author
This blog is for educational purposes only and is not intended to diagnose or treat illness. Consult with your care provider for your healthcare needs.
