Skyline University Nigeria

Brain Fog: a long term consequence of COVID-19 infection

Many people who had a past history of COVID-19 infection are now presenting with cognitive problems with attention, concentration, and memory loss [1]. The doctors are now referring to these problems as COVID-associated ‘Brain Fog.’ Though Brain fog is not a medical or scientific term; it is used by individuals to describe how they feel when their thinking becomes sluggish. The fogginess of the brain is a frequently reported symptom these days, and can be best described as:

  • Cloudy thinking
  • Inability to concentrate the way that one earlier could
  • Lapses in memory
  • Losing train of thought such as forgetting in mid-sentence what you were planning to say, or asking the other person “what was I saying?” frequently
  • Getting distracted easily, with the feeling that the mind is refusing to focus
  • Poor motivation, sluggishness, fuzziness

Remember the sickly feeling that we all experience when we are recovering from flu or any illness, jet-lagged or on an anti-allergic medication that makes us fuzzy for a few hours. I am sure that we all have experienced this feeling at some point of time in our life. However, never do these symptoms become so aggravated to get noticed on a daily basis affecting the quality of life and work. Most of the time the sickly feeling disappears once we recover from illness or get adjusted to the new time zone or the side effects of the medication just wear off [2]. However, if this uneasy feeling persists for a long time and disturbs the daily routine then one may be possibly suffering from ‘Brain Fog.’ Reporting of Brain Fog has gone up significantly since the COVID pandemic. It is included as one of the features of long COVID or Post-COVID Syndrome.

‘Chemo brain’ or ‘Chemo Fog’ is a condition in which a cancer patient experiences sluggishness, fuzziness, and a low feeling after receiving chemotherapy. This is because of the inflammation of neurons due to chemotherapy. It is now known that the COVID virus may cause inflammation or swelling of several organs and tissues. The main brunt has been on the lungs but the involvement of other organs was also there that included the brain [3]. Many COVID patients complained of loss of smell as one of their symptoms. This indicates that there may be mild brain inflammation produced by the COVID infection, which may be the cause of ‘Brain Fog.’

According to medical experts, the best way to deal with the problem of ‘Brain Fog’ is to perform an aerobic exercise like walking. While there is no established ‘dose’ of exercise to improve brain health, it’s generally recommended that one can walk 30 minutes a day, five days a week. Maintain a healthy diet that includes fruits, vegetables, nuts and beans, and whole grains. And completely abstain from alcohol and drugs. A normal sleep routine of 7-8 hours every day. The body can heal itself when we sleep at night. Sleep deprivation is one of the main reasons for many mental illness.  

Brain Fog may however also happen in people who have not had COVID infection. If the symptoms persist then one should consult a doctor and investigate the blood glucose level, blood pressure, hemoglobin, vitamin B12, and vitamin D levels. One should also look out for hormonal changes, especially irregular periods or thyroid dysfunction. Fogginess of the brain can also be an early symptom of dementia.

It is believed that COVID-induced ‘Brain Fog’ will improve gradually and most will gain back their brain’s vitality. However, if the symptoms persist then one should consult a qualified medical expert.  



  1. Choudhuri G. Coping with Brain Fog. November 7, 2022.
  2. Budson A E. What is COVID-19 brain fog — and how can you clear it? March 8, 2021, Harvard Health Blog.
  3. Fernández-Castañeda, A., Lu, P., Geraghty, A. C., Song, E., et al. (2022). Mild respiratory COVID can cause multi-lineage neural cell and myelin dysregulation. Cell, 185(14), 2452–2468.e16.

Dr. Sanjoy Kumar Pal is a Professor of Biology in Skyline University Nigeria. He has a PhD. in Animal Genetics from Indian Veterinary Research Institute, India.

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