Clearing the Haze: Understanding and Overcoming Brain Fog

by | Feb 10, 2023 | Blog, General Wellness, Mental Health

Brain fog is one of the common symptoms I see in my practice. Brain fog is a term used for a range of symptoms, including difficulty focusing, trouble concentrating, forgetfulness, confusion, and overall mental fogginess. In functional medicine, we have options to manage and improve brain fog naturally while looking at and addressing the root causes of the problem.

How to Improve or Get Rid of Brain Fog

In this article, I want to explore brain fog. I will discuss the symptoms of brain fog, the potential causes of brain fog, and the underlying health issues associated with brain fog. Finally, I will share my top recommendations to reduce your risks of brain fog and improve your symptoms naturally. Read on to learn how to boost your brain power and combat brain fog.

What Is Brain Fog?

Brain fog is characterized by mental fatigue, a lack of mental clarity, an inability to focus and concentrate, memory issues, and just feeling mentally ‘foggy’. Though brain fog is not a medical condition, but rather a symptom of all kinds of health issues, it is not a new concept. 

According to a 2022 article published in New Scientist, the concept of brain fog in medicine dates back to the early 1800s (1). Georg Greiner, a German scientist, explained various cognitive deficits as “fogging of the light of reason” and “clouding of consciousness”. The term has been used off and on since then. 

It became a popular term around the 1990s when people with chronic fatigue syndrome (CFS), fibromyalgia, and autoimmune issues started describing their cognitive symptoms as brain fog. For some, brain fog is an occasional inconvenience. For others, it’s part of daily living. It can seriously disrupt their work, education, or even daily tasks. Brain fog is not to be confused, however, with memory loss and cognitive decline associated with dementia and Alzheimer’s disease.

Symptoms of Brain Fog

If you have brain fog, chances are I don’t have to describe its symptoms to you. They may include:

  • Forgetfulness and memory issues
  • Difficulty concentrating
  • Problems focusing
  • Dissociation
  • Cognitive slowness
  • Excessive effort needed for cognitive tasks
  • Fuzziness or pressure
  • Lack of mental clarity
  • Mental fatigue
  • Mental fogginess
  • Fatigue

Some people may also experience insomnia, sleep issues, headaches, irritability, anxiety, low motivation, or depression connected to or as a consequence of brain fog. According to a 2022 research published in Neuropsychiatry, over half of the subjects dealing with symptoms experienced their brain fog related to other health issues, including COVID-19, long-COVID, neurodevelopmental issues, psychiatric and mental health conditions, autoimmune disorders, and functional disorders (2). This means that most people with brain fog likely also experience other chronic symptoms of other physical or mental health issues. 

Causes of Brain Fog

Considering that brain fog can be the symptom of various underlying health issues, pinpointing the specific cause is difficult. However, there are some underlying issues that may play a role in the development of brain fog.

Potential causes may include:

Chronic Stress

Chronic stress can seriously impact your health (3). It is also one of the potential causes of brain fog. According to a 2022 review published in the Neurobiology of Stress, chronic stress can affect your cognition, brain health, and mental health throughout your entire lifespan (4). It may affect memory and processing speed. It may increase the risk of depression and other mental health issues. Chronic stress may cause your brain to feel exhausted, lead to mental fatigue, and result in symptoms of brain fog.

Poor Sleep

Enough restorative sleep is essential for a healthy brain. Poor sleep is one of the potential causes of brain fog. A 2022 study published in Nature has found a link between sleep duration and cognitive abilities (5). They found that getting at least seven hours of sleep may be linked to increased cognitive performance in 38 to 73-year-old participants. Sleeping less may lead to a decline in cognitive abilities with every hour. A lack of sleep or poor quality sleep may lead to poor concentration, trouble focusing, memory problems, and cloudy thoughts.

Diet and Nutrient Deficiencies

A poor diet may be one of the top underlying causes of brain fog. Nutrient deficiencies from a poor diet may be especially problematic. According to a 2020 study published in Frontiers in Human Neuroscience, a healthy diet may improve cognitive function and reduce the risk of dementia (6). Researchers noted that vitamins, polyunsaturated fatty acids (PUFAs), and flavonoids are all critical for brain health. B vitamins, especially vitamin B12, are particularly important for brain health (7).

Food Sensitivities

Consuming foods that you are sensitive or allergic to may also lead to brain fog. According to a 2019 study published in Behavioral Brain Research, food allergies and food sensitivities may increase inflammation in the brain and cause cognitive issues (8). Aspartame, MSG, gluten, casein, dairy, peanuts, eggs, and shellfish are some common food culprits. However, you may be allergic or sensitive to other less-common foods or ingredients.

Histamine Intolerance

Brain fog is a common complaint in those with histamine intolerance and mast cell activation syndrome (MCAS). According to a 2015 research published in Frontiers in Neuroscience, when inflammatory agents, including histamine, are released from your mast cells they may activate the microglia and increase the risk of brain inflammation (9). This may lead to symptoms of fogginess.

Hormonal Changes

Hormonal fluctuations and hormonal changes in your body may also affect your brain and trigger brain fog. According to a 2018 study published in The Malaysian Journal of Medical Sciences, hormone levels may impact neuronal network interactions and cognitive function (10). Menstruation, PMS, pregnancy, perimenopause, menopause, stress, aging, and other hormonal imbalances may affect memory and concentration. According to a 2019 study published in Medicina (Kaunas), the drop in estrogen during menopause may increase poor concentration, forgetfulness, and other related symptoms (11).

Gut Dysbiosis

Your gut influences your entire body. Your gut and your brain are in constant communication with each other. It’s called the gut-brain axis. It’s a bidirectional relationship, meaning that your gut health can affect your brain health and cognition, but your neurological and brain health may also affect your gut microbiome health. No wonder that gut dysbiosis is a common underlying issue behind brain fog. According to a 2016 review published in Molecular Psychiatry, gut dysbiosis may negatively impact brain function and mental health (12). Gut dysbiosis may also increase your risk of fibromyalgia, chronic fatigue syndrome, hormonal imbalance, and autoimmunity, which may all be characterized by brain fog as a symptom.

Mitochondrial Dysfunction

Mitochondrial dysfunction is another issue that may lead to brain fog. As we all know from high school, the mitochondria is the powerhouse of the cell. Its health and function affect your energy levels, brain function, and overall well-being. According to a 2017 study published in Human Molecular Genetics, mitochondrial dysfunction may lead to cognitive issues (13). 

Blood Sugar Imbalances

Blood sugar imbalances may also increase your risk of brain fog. Balanced glucose (sugar) levels are essential for your health. Your body relies on glucose for energy. However, if you are experiencing blood sugar fluctuation, sugar spikes, and sugar crashes, you can experience poor concentration, memory issues, and other symptoms of brain fog. According to a 2015 review published in the Annals of the New York Academy of Sciences, blood sugar issues and diabetes may cause cognitive dysfunction (14).

Mental Health

Your mental health may also affect your cognition and brain function. Low mood, depression, PTSD, ADHD, and anxiety may all increase the risk of brain fog. A 2022 scientific article published in Australas Psychiatry has found that brain fog is common in those with depression (15). The author indicated that asking patients about brain fog can help with diagnosis.


Certain medications may also cause brain fog as a side effect. According to a 2020 review published in the European Journal of Pharmacology, chemotherapy for cancer may cause brain fog, also known as chemo brain (16). A 2022 study published in Clinical Nursing Research has found that thyroid medication may also increase the risk of brain fog (17). According to a 2005 review published in the Journal of Clinical Psychiatry, long-term use of benzodiazepines (such as Lorazepam or Valium) may also lead to brain fog (18). Sleep aids and psychiatric medications may also increase your risk. Lowering the dose or switching medications may improve your symptoms.

Post-COVID and Post-Viral Syndrome

You may develop brain fog as a long-term consequence of certain viral infections. According to a 2022 study published in the International Journal in Environmental Research and Public Health and a 2022 research published in Neuropsychiatry, brain fog is a common symptom of long hauler syndrome after COVID-19 (19, 2). You may develop post-viral syndrome from other viral infections too, including the flu, pneumonia, and the Epstein Barr Virus (EBV) which can also lead to fogginess.

Medical Conditions

Finally, brain fog has been linked to fatigue, blood sugar issues, chronic inflammation, and all kinds of chronic health issues (14). For example, it is a common complaint of people with chronic fatigue syndrome and fibrofog in fibromyalgia (20, 21).  Other health issues that may present brain fog as a symptom may include headaches, migraines, thyroid issues, histamine intolerance, autoimmune diseases, multiple sclerosis, diabetes, depression, anemia, and dehydration.

Diagnosis of Brain Fog

Since brain fog is more of a sign of a problem and is associated with a variety of underlying health issues, there is no one specific way to diagnose it. During your appointment, your doctor will go over your symptoms, health history, diet, mental health, physical activity level, medications and supplements you are taking, and other information related to your health. They will perform a physical exam. 

Depending on your complaint, they may recommend some blood tests to detect thyroid issues, blood sugar imbalances, nutrient deficiencies, infections, inflammation, liver or kidney problems, anemia, or other underlying health causes. In some cases, they may recommend some imaging, such as a CT or MRI scan, to rule out more serious problems depending on your combination of symptoms. They may recommend a sleep study to look into sleep disorders, allergy testing, or visiting a therapist.

Recommendations for Brain Fog

Recommendations may depend on the underlying cause. However, there are some general recommendations that may help to address the causes of the issue, reduce your risk, and improve your symptoms. Here is what I recommend:

  • Follow a nutrient-dense diet. Remove refined sugar, refined oil, artificial ingredients, additives, junk food, and overly processed foods. Eat plenty of greens, vegetables, herbs, spices, sprouts, fruits, fermented food, nuts, seeds, grass-fed meat, pasture-raised poultry and eggs, wild-caught fresh fish and seafood, and wild game.
  • Get tested for food allergies and food sensitivities. Remove any triggers from your diet.
  • If you have histamine intolerance or mast cell issues, follow a low-histamine diet and reduce your overall histamine load.
  • Get tested for nutritional deficiencies and work on improving them with the guidance of a functional medicine practitioner
  • Get enough sleep. I recommend aiming for 7 to 9 hours of restorative sleep each night.
  • Move your body regularly throughout the day. Exercise at least 5 days a week for 20 to 30 minutes, combining cardiovascular and strength-training workouts.
  • Reduce your stress level. Try meditation, breathwork, journaling, guided muscle relaxation, and gratitude.
  • Improve your workload. Avoid multitasking and overcommitting yourself. Ask for help if needed.
  • Improve your gut health with the health of prebiotic-rich foods, fermented food, and probiotic supplements. If you have histamine intolerance, skip the fermented food as it can be triggering.
  • Try some supplements that may support brain health and cognitive function, including omega-3 fish oil supplements, vitamin B12, B vitamins, and adaptogens (22, 23, 24, 25). I recommend that you seek guidance from your healthcare practitioner before using any supplements.
  • Consider ways to support mitochondrial health.  This may include a combination of supplements, such as CoQ10 or Carnitine; exposure to red light as part of photobiomodulation therapy; or even hyperbaric oxygen in the right circumstance.
  • Detoxify, and limit exposure to neurotoxins including heavy metals and pesticides, as well as indoor pollutants or allergens, such as mold.
  • If affected by fragrances, consider scent-free living. Try to avoid indoor environments where fragrances are common. My medical clinic for example is a “scent-free” zone. At home, choose scent-free cleaning, laundry and personal hygiene products.
  • Look into underlying health issues, such as fibromyalgia, chronic fatigue syndrome, long-COVID, hormonal imbalances, or autoimmunity. Work with a functional medicine practitioner on an appropriate protocol to improve your specific health conditions. Tip: Make an appointment today and I would be happy to guide you back to health.

Next Steps

If you are interested in improving your liver health, I recommend that you speak with your doctors first for more personalized health information and support. I invite you to schedule a consultation with me here to see if you can benefit from the strategies listed in this article.

If you are dealing with any chronic health issues, and for advice on how to improve your nutrition and health, I welcome you to start a functional medicine consultation with me for further personalized guidance. You may book your consultation here

Check out my Histamine Intolerance Course here. Learn on your own time, from anywhere. Get an inside look at the most helpful functional medicine tests for pinpointing imbalances, ways to identify and manage the most common (and sometimes surprising) mast cell triggers, and learn what to eat, what to avoid, and why.

Learn more about working with Dr. Gannage