Brain fog

Dr. Ayush PandeyMBBS,PG Diploma

October 14, 2020

October 14, 2020

Brain fog
Brain fog

Brain fog is an altered state of consciousness in which the person is less wakeful, less aware, less alert and less focused than usual.

Someone with brain fog is unable to think clearly, communicate clearly or concentrate. They may also have trouble remembering things.

Also known as a clouding of consciousness, disturbance of consciousness and mental fog, brain fog can occur in several situations.

Brain fog can also be a side-effect of certain medications and therapies like chemotherapy (chemo fog or chemo brain is a type of cognitive or thinking dysfunction that can occur as a result of cancer therapies like chemotherapy, radiotherapy and immunotherapy).  

Brain fog can be short-term or it can be present for longer durations. It may be a neurological symptom of an underlying problem or it could be linked to lifestyle or life-stage and nothing to worry about.

The treatment of brain fog depends on the cause. For example, if a particular medicine is making your brain fuzzy, you could talk to your doctor about changing your prescription. If the cause is gluten sensitivity, then eating only gluten-free foods could help. And if the cause is diabetes, then managing your blood sugar levels will help to keep the brain fog at bay.

Sometimes the remedy is quite simple (and obvious). For example, if your brain is foggy because you have been burning the midnight oil for a few nights in a row, then getting adequate sleep can reduce brain fog. (Read more: Sleep and mental health)

Read on to know about brain fog as a kind of altered state of mind, what it could signify, symptoms of brain fog and brain fog in the context of COVID-19.

What is brain fog?

Brain fog is an altered state of consciousness in which the person is not as wakeful or alert as usual.

A person with brain fog may not be completely aware of where they are or their surroundings. He/she may not be able to think clearly, remember things clearly and concentrate. Some people with brain fog can feel befuddled or disoriented as well. Patients often complain of a foggy feeling—like they are trying to reach their thoughts and memories through a dense fog. Most people in this condition tend to work slower and get less done (lower productivity) than their norm at other times.

Brain fog is a relatively mild cognitive dysfunction where the level of consciousness of a person is compromised. To see this in the proper context, consider the following classification of states of altered consciousness, as described by Suzie C. Tindall in Clinical Methods: The History, Physical, and Laboratory Examinations. (3rd edition):

  • Clouding of consciousness or brain fog: A mildly altered state of mind where the patient is less attentive and wakeful than usual.
  • Confusional state: The next level in altered consciousness, in which the patient may be disoriented and bewildered. They may also have difficulty following simple instructions.
  • Lethargy: We tend to think of lethargy as extreme tiredness and unwillingness to move. But in this context, lethargy is a state in which the patient is very sleepy. He or she is able to rouse themselves if there is adequate stimulus but they would drift back to sleep when that stimulus is taken away.
  • Obtundation: A person in this condition has even less interest in their surroundings and slower response to stimuli than someone with lethargy. People in this state sleep more than normal and usually feel drowsy even when they wake up.
  • Stupor: In this state, the patient would be unresponsive unless there is a clear, strong and repeated stimulus to arouse them.
  • Coma: We are all familiar with this stage; a patient in a coma cannot be woken up.

Please note: This is not to say that brain fog is a step towards the development of these other conditions. This classification has been shared here only to clarify what altered state of consciousness can mean and where brain fog stands in the classification.

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Symptoms of brain fog

Brain fog is not a disease but it can be a symptom of some diseases. As such, it can be useful to know the signs of brain fog. Someone with brain fog may experience some or all of the following symptoms:

  • Forgetfulness: Inability to remember appointments and thing on your to-do list are common, as is the inability to remember the right word while you are having a brain fog episode
  • A feeling of dullness or vagueness (fogginess)
  • Slower response times
  • Reduced awareness of surroundings
  • Poorer performance on cognitive tasks
  • Being more disorganized than usual
  • Having trouble concentrating
  • Not being able to learn new skills
  • Not being able to multitask
  • Memory problems, including verbal and visual memory issue:
    • Verbal memory problems can present as an inability to remember a conversation you had while you were in a brain fog
    • Visual memory issues might make it difficult for you to recall an image or a list of words

Causes of brain fog

There can be many reasons behind brain fog. For the sake of clarity, let’s divide these by underlying disease and other causes:

Brain fog due to an underlying disease may occur in:

Other causes of brain fog include:

  • Stress
  • Pregnancy
  • Consuming alcohol
  • Drug use
  • Certain medicines like statins, corticosteroids (example, prednisone) and sleeping pills, and therapies like chemo
  • Dehydration
  • Menopause

COVID brain fog

We know that long COVID is real and that many patients continue to experience symptoms like breathlessness, memory impairment and sleep disruptions for several weeks after they’ve tested negative for the SARS-CoV-2 virus.

These patients, colloquially called the long-haulers, often report symptoms like difficulty focusing, and trouble remembering things and communicating. These, as we have seen above, are all the signs of brain fog.

There could be many reasons for brain fog in recovering COVID-19 patients. Here are some of the proposed theories for why this occurs:

  • The virus can enter the brain and cause damage to the cells. The brain damage, in turn, can cause the mental fog (read more: Can COVID-19 cause permanent brain damage?)
  • Post-COVID can cause inflammation and damage to various organs including the brain. This, too, may contribute to the brain fog (read more: Neurological symptoms of COVID-19)
  • Hypoxemia or low blood oxygen, when COVID-19 infection affects the lungs severely, can also present as brain fog (read more: Can COVID-19 cause permanent lung damage?)
    An observational study of over 12,000 patients hospitalised in New York between 10 March 2020 and 20 May 2020 found no signs that the COVID-19 virus (SARS-CoV-2) enters the brain or attacks the central nervous system directly. Yet, the researchers found that 13% of hospitalised patients developed neurological disorders—mainly “toxic/metabolic encephalopathy (6.8%), seizure (1.6%), stroke (1.9%), and hypoxic/ischemic injury (1.4%)”.
  • Post-traumatic stress disorder (PTSD) in recovering patients, especially those who had severe disease and had to be hospitalised: On 26 August 2020, Andrew Levine of the University of California, Los Angeles, and E. Kaseda of the Rosalind Franklin University of Medicine and Science published an article in the peer-reviewed journal The Clinical Neuropsychologist, in which they argued that the cognitive and emotional difficulties that COVID-19 long-haulers were facing could be a sign of PTSD. The authors explained that hospitalization, especially procedures like intubation and ventilation, could increase the risk of PTSD in patients who are already fearful about the new disease. Additionally, they wrote, PTSD was also noted in previous deadly outbreaks of coronavirus infection—first, the SARS outbreak in 2002-03, and then, the MERS outbreak in 2012 (read more: Risks of intubation and ventilation in COVID-19).
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Diagnosis of brain fog

Brain fog is not a medical term. However, it is a useful umbrella term to describe signs of cognitive impairment that are not severe enough to be called confusion (remember the levels of consciousness outlined earlier), yet these signs are enough to interfere with the normal day-to-day life of a person. Most patients find brain fog frustrating because they often can’t describe what is happening to them while it is happening.

Having said that, you should visit a doctor if your neurological symptoms like memory problems, fuzzy thinking, slower speed in completing cognitive tasks (compared to your own past performance) and difficulty in communicating persist beyond a day. Visit a doctor if you have liver disease and your brain fog is getting worse.

If you forget appointments, forget conversations you have had, can’t find the words or use the wrong words because you can’t remember the right ones, these could also be signs of brain fog—if these issues are disrupting your life, then also it might be worth visiting a doctor to check that there is no underlying problem.

To diagnose any underlying condition, the doctor will conduct a physical examination and ask you questions about your diet, exercise regime, stress levels, sleep schedule, alcohol and drug use, overall health and mental health. Make sure you tell the doctor about any additional symptoms such as fatigue or pain, and if you are taking any medications including birth control pills and statins for high cholesterol.

Based on the initial analysis, the doctor may order a blood test to rule out diabetes, inflammatory disease, nutritional deficiencies, liver disease (liver function test), kidney disease (kidney function test) and thyroid problems (thyroid function test); RT-PCR test to rule out infections. He/she may also order some imaging tests such as MRI scansCT scans to rule out problems like a brain injury or brain bleed. In case your doctor suspects sleep apnea, he/she may recommend a sleep study. For diagnosis of anxiety, depression and other mental health conditions, the doctor may refer you to a psychologist.

Treatment of brain fog

The treatment of brain fog depends on the cause. However, some common interventions to improve symptoms in the short run may involve giving the patient fluid therapy with an intravenous saline drip, using stimulant medications or giving an intramuscular injection of vitamin B12. (Make sure to tell your doctor about any existing health conditions and any medications you’re taking before the medical intervention.)

The doctor may also ask you to make some lifestyle changes—like getting regular exercise, eating healthy (eat with the rainbow or include vegetables and fruits of all colours in your diet to avoid vitamin deficiencies, is a great dietetic rule to follow), getting adequate sleep (seven to eight hours daily), reducing stress, reducing your intake of coffee, energy drinks (they contain caffeine) and alcohol—to fight brain fog.


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Medicines for Brain fog

Medicines listed below are available for Brain fog. Please note that you should not take any medicines without doctor consultation. Taking any medicine without doctor's consultation can cause serious problems.

Medicine Name




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