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Brain Fog: Symptoms, Causes & Treatment

Devon Scoble

Medically reviewed by

Stefano Guandalini, MD


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Confusion, memory problems, headaches, fatigue—these are the key symptoms behind the phenomenon popularly known as brain fog. Although not an official diagnosis, the catch-all term represents real symptoms and real suffering. 

What is brain fog?

If you find it hard to think and concentrate, or if you can describe your mental state as unfocused, fuzzy—or yes, foggy—then you may be experiencing brain fog. Remember, brain fog is a popular term, not a medical one, so if it feels like the right way to describe your experience, go ahead and use it. Just keep in mind that brain fog symptoms are simply that—symptoms. In order to clear the fog, you’ll first need to know what’s causing it.

What causes brain fog?

Asking what causes brain fog is like asking what causes happiness or unhappiness. The answer is always personal, and getting to it requires understanding the person behind the fog, their lifestyle, and their symptoms.

That said, there are several conditions that we know are associated with reduced mental clarity. The following causes of brain fog are not mutually exclusive, and many overlap—it’s possible to be pregnant and celiac, for instance, while Hashimoto’s thyroiditis is an autoimmune and a hormonal condition. But if you’re looking to narrow down what’s causing your brain fog, these common conditions can be a good place to start:

Nutritional deficiencies, food allergies and food intolerances

Dr. Stefano Guandalini is Professor Emeritus, University of Chicago, and the founder of the University of Chicago Celiac Disease Center. When his patients complain of brain fog, he’s most likely to investigate nutritional deficiencies or adverse reactions to particular ingredients. For him, that means ruling out the following conditions, each of which can affect cognition in their own way: 

  • Celiac disease¹
  • Anemia² or iron deficiency³
  • Vitamin B12 deficiency

Hormonal causes

A number of hormones can influence cognition, including estrogen, and thyroid stimulating hormone. 

Hormonal causes of brain fog can include:

  • Thyroid conditions such as Hashimoto’s thyroiditis and Graves’ disease
  • Pregnancy¹⁰
  • Menopause¹¹
  • Perimenopause¹²

Autoimmune diseases and inflammatory conditions

"It is becoming clear that the immune system plays an essential role in neurologic processes involved in cognition," says Dr. Guandalini.

Specifically he points to the immune system’s influence on such synaptic plasticity—the brain’s ability to modify its own circuits, and turn experiences into memories¹³—and its effect on adult neurogenesis—a key process in adult mood and memory involving the creation of new neurons.¹⁴

"Autoimmune disorders that cause chronic inflammation could lead to altered function of the central nervous system," he says.

With that in mind, several autoimmune conditions could potentially lead to brain fog. Some common ones include:

  • Celiac disease¹⁵
  • Sjogren syndrome¹⁶
  • Lupus¹⁷
  • Multiple sclerosis¹⁸
  • Rheumatoid arthritis¹⁹
  • Type 1 diabetes²⁰
  • Thyroid conditions such as Hashimoto’s thyroiditis²¹ and Graves’ disease²²

Inflammatory conditions such as colds, flu²³ and COVID-19²⁴ can also cause symptoms of brain fog.

Psychological causes

Although they are easy to distinguish with words, in experience, mental and physical health are inseparable—our mental state absolutely affects our physical wellbeing, and vice versa. 

Here are some common psychological causes of brain fog: 

  • Depression²⁵
  • Anxiety²⁶
  • Post-traumatic stress disorder²⁷
  • Attention deficit hyperactivity disorder

Situational causes

Just like actual fog, brain fog can be a temporary state, coming and going when it's trigger, or cause does.

Some situational causes of brain fog symptoms include:

How to get rid of brain fog

If you’re experiencing regular brain fog, the first step in your journey to clarity is figuring out why. 

"There’s no one-size-fits-all response," says Dr. Guandalini.
"If a patient has a history of a disorder associated with brain fog, such as lupus, then the cause is immediately apparent. Or they may have a suspected cause in mind—depression linked to a specific life event, for instance."

But usually when a patient approaches a doctor for help with brain fog, they’re doing so because they don’t know what’s causing their suffering. “In this case, a thorough medical assessment is indicated,” he says.

Since there’s no one brain fog test, Dr. Guandalini recommends discussing your symptoms with your family doctor, stressing how important it is to speak with a medical professional who understands your history specifically. 

"Brain fog in a patient known to have Hashimoto thyroiditis may signify an inadequate level of hormonal replacement, and this will be the primary focus of the assessment,” he says.
"On the other hand, a woman with a history of heavy periods, or endometriosis, is more likely to suffer from iron deficiency. A teenager who has just lost a parent and feels depressed will be approached from a psychological point of view, and so on."

That said, there are some general lifestyle practices known to improve mental and physical wellbeing: 

1. Eating healthfully

The link between healthy eating and healthy living is well established. The famously nutritious Meditterranean diet—high in vegetables, whole grains, lean protein, and plant-based fats, and low in processed foods and saturated fats—is also associated with a 25 percent lower risk of depression when compared to a typical Western diet.²⁹ Some foods that are specifically known to benefit the brain and better cognition are: leafy greens, fatty fish, walnuts, avocados and berries.³⁰


Exercise is associated with a range of health benefits, including improved sleep, mood and cognition, and reduced risk of chronic illness.³¹ The US Department of Health and Human Services recommends that adults get at least two-and-half hours of moderate intensity exercise each week, which they define as “anything that gets your heart beating faster.”³²

3. Sleeping well

Anyone who’s ever experienced a bad sleep knows that it can create a sense of mental fog, and studies bear this out—inadequate sleep can impair judgement, increase the risk of accidents and infections, and exacerbate anxiety and depression.³³ Most adults function best on seven to nine hours of sleep per night.³⁴

4. Meditating 

Studies show that mindfulness meditation is associated with reduced stress, anxiety and depression. A regular meditation practice may even support the immune system³⁵ and protect the brain from age-related deterioration.³⁶ These days, a variety of internet-based classes and apps offer guided meditations for beginners and experienced meditators alike.

In addition to the tips above, Dr. Guandalini also recommends maintaining an active social life—in person, when possible, or by phone or Zoom when not. 

Positive lifestyle habits aren’t a cure for unavoidable causes of brain fog such as chronic inflammatory and autoimmune conditions, but they’re still likely to help. At the very least, they won’t hurt.

"Being sure to have a balanced, healthy diet and having the right amount of physical exercise and social interaction is always good advice, and it’s never a bad idea to try those things first,” says Dr. Guandalini.

References +
  1. Celiac Disease Foundation. “Brain Fog” Improves in Celiac Patients After Starting a Gluten-Free Diet .
  2. Fisher Center for Alzheimer’s Research Foundation. Anemia Tied to Mild Cognitive Impairment Risk .
  3. Psychology Today. Heavy Metal: Iron and the Brain .
  4. ScienceDirect. Diet and Nutrition in Dementia .
  5. Malaysian Journal of Medical Sciences. Hormonal Influences on Cognitive Function .
  6. Canadian Institutes of Health Research. Estrogen and Cognitive Functioning in Women: Lessons We Have Learned .
  7. Psychiatry Investigation. Thyroid Stimulating Hormone, Cognitive Impairment and Depression in an Older Korean Population .
  8. Current Opinion in Endocrinology, Diabetes and Obesity. Psychiatric and cognitive manifestations of hypothyroidism .
  9. BMJ Open 2019. Structural brain changes in hyperthyroid Graves’ disease: protocol for an ongoing longitudinal, case-controlled study in Göteborg, Sweden—the CogThy project .
  10. The Medical Journal of Australia. Cognitive impairment during pregnancy: a meta-analysis .
  11. WebMD. More Evidence Menopause ‘Brain Fog’ Is Real .
  12. Harvard Health Publishing. Sleep, stress, or hormones? Brain Fog During Perimenopause .
  13. The Biology of Thought via ScienceDirect. Synaptic Plasticity .
  14. The University of Queensland Australia. Adult neurogenesis .
  15. Celiac Disease Foundation. “Brain Fog” Improves in Celiac Disease Patients After Starting a Gluten-Free Diet .
  16. Sjogren’s Syndrome News. Dealing with ‘Brain Fog’ in Sjogren’s Syndrome .
  17. Hospital for Special Surgery. Lupus Fog – Changes in Memory and Thinking .
  18. Multiple Sclerosis Trust. Thinking and memory problems .
  19. Rheumatology Advisor. Rheumatoid Arthritis and Cognitive Impairment .
  20. American Diabetes Association. The Effects of Type 1 Diabetes on Cognitive Performance .
  21. Current Opinion in Endocrinology, Diabetes and Obesity. Psychiatric and cognitive manifestations of hypothyroidism .
  22. BMJ Open 2019. Structural brain changes in hyperthyroid Graves’ disease: protocol for an ongoing longitudinal, case-controlled study in Göteborg, Sweden—the CogThy project .
  23. The Globe and Mail. Why ‘brain fog’ from the common cold isn’t all in your head .
  24. Harvard Heatlh Publishing. What is COVID-19 brain fog—and how can you clear it?
  25. Neuropsychiatric Disease and Treatment. Cognitive impairment in depression: recent advances and novel treatments .
  26. Frontiers in Human Neuroscience. The impact of anxiety upon cognition: perspectives from human threat of shock studies .
  27. Frontiers in Integrative Neuroscience. Emotion and cognition interactions in PTSD: a review of neurocognitive and neuroimaging studies .
  28. American Cancer Society. Chemo Brain .
  29. Harvard Health Publishing. Nutritional psychiatry: Your brain on food .
  30. Harvard Health Publishing. Foods linked to better brainpower .
  31. Department of Health and Human Services USA. Physical Activity Guidelines for Americans .
  32. Department of Health and Human Services USA. Physical Activity Guidelines for Americans .
  33. Sleep Foundation. How Lack of Sleep Impacts Cognitive Performance and Focus .
  34. Centers for Disease Control and Prevention. How Much Sleep Do I Need?
  35. Annals of the New York Academy of Sciences. Mindfulness meditation and the immune system: a systematic review of randomized controlled trials .
  36. Frontiers in Psychology. Forever Young(er): potential age-defying effects of long-term meditation on gray matter atrophy .

Updated on
August 11, 2022
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