Update on COVID-19 and How It Changes in the Brain
By Barbara Koltuska-Haskin, Ph.D.

COVID-19 is a systemic illness that often involves the central nervous system.

Key points

  • About one-third of COVID-19 survivors suffer from a variety of symptoms long after they were first infected.
  • COVID-19 can affect the brain, even in asymptomatic patients.
  • Brain fog is the most frequently reported symptom in COVID-19 survivors.

Neuroimaging and neuropathological studies results.

There is agreement that COVID-19 is a systemic illness often involving the central nervous system. Reportedly, neurological symptoms affect more than 30 percent of COVID-19 patients. Frequently, there is neurological involvement in all stages of this illness, such as acute, subacute, chronic, and post-acute sequelae.

Even asymptomatic patients can develop neurological symptoms and conditions such as headaches, myalgia (muscle pain), Guillain-Barre syndrome (in which a person's immune system attacks peripheral nerves), encephalopathy (brain disease or malfunction), and myelopathy (neurologic deficits related to the spinal cord).

The magnetic resonance imaging (MRI) studies of COVID-19 patients revealed a reduction in grey matter thickness mainly in the orbitofrontal cortex (that processes sensory information, decision-making, and emotions.) and the parahippocampal gyrus (that plays an important role in memory encoding and retrieval.) and are associated with the greater reduction in global brain size and greater cognitive decline. The virus can directly infect endothelial cells of the brain (cells that make up the lining of blood vessels), which may promote clot formation and stroke.

In some patients, COVID-19 causes an ischemic stroke (caused by a lack of blood reaching part of the brain). The review of strokes in 455 patients (Finsterer J. et al., 2022) indicates that stroke occurs in all age groups and predominantly in males. The ischemic stroke is multifactorial but usually embolic (a blockade of a blood supply to the part of the brain by a blood clot).

The researchers also indicated cardiovascular risk factors are frequently present in patients who suffered from a stroke and that COVID-19 stroke may co-occur with the onset of pulmonary symptoms or up to 40 days later. Interestingly, when the virus enters the brain, it mainly affects astrocytes (glial cells in the central nervous system that supply the building blocks of neurotransmitters) and may cause neuronal death or dysfunction (Crunfli, F. et al., 2022). The researchers suggest that these processes could contribute to the structural and functional changes in the brains of COVID-19 patients.

Cognitive and mental health studies results.

Quite a few studies now indicate cognitive changes after COVID-19 illness. The cognitive problems mainly include memory, attention, executive functions, processing speed, and visuospatial deficits, but may also include other brain functions.

The research indicates that cognitive impairments can be seen even in asymptomatic patients. Also, non-hospitalized patients have a significantly higher likelihood of developing mental health problems. These problems may include mood dysregulation, depression, anxiety, insomnia, and even psychosis.

Some research suggests that some patients can develop cognitive and psychotic symptoms even two years after the infection. This, unfortunately, also includes dementia.

About one-third of COVID-19 survivors suffer from a variety of symptoms long after they were first infected. "Brain fog" is the most frequently reported and is one of the symptoms that persist for weeks and months after the disease and significantly affects survivors' everyday functioning.

Brain fog is not medical terminology. It is rather a description of patient's use for various symptoms they are experiencing. It is mainly described as slow and sluggish thinking and fuzziness, but it can also include searching for words, memory, concentration, problem-solving difficulties, and fatigue. The good news is that usually, there is some improvement in neurological deficits a few months after the infection.

However, there is a correlation between symptom severity and the degree of neurological deficits. An interesting review was published in 2023 (Zhao, S. et al., 2023). The researchers reviewed cognitive changes during the acute and chronic stages of COVID-19.

The results suggest that problems with executive functioning were frequently reported during the acute stage. However, during the chronic phase (three months to two years), mild and moderately infected patients reported attention, executive functioning, and memory deficits. However, the good news is that the recovery can occur within the first year after the infection.

The research indicates that severe COVID-19 is associated with long-term cognitive impairments, but even mild COVID-19 can cause changes in the brain that can lead to cognitive deficits. Therefore, it is best to do whatever it takes not to get sick. However, if you have had COVID-19 and are experiencing some cognitive deficits, it may be beneficial to contact your community neuropsychology office and complete a neuropsychological evaluation.

This will show if you have some cognitive deficits (memory, attention/concentration, information processing, etc.), how much (mild, moderate, severe impairments), and how to improve or maintain your cognitive functioning.


About the Author

Barbara Koltuska-Haskin, Ph.D., is a neuropsychologist in private practice in Albuquerque, New Mexico with over 30 years of clinical experience, and the author of How My Brain Works: A Guide to Understanding It Better and Keeping It Healthy. Her book has won 2 International Book Awards and 5 National Book Awards.

Dr. Barbara Koltuska-Haskin has received her first foreign translation. How My Brain Works was recently translated into Polish and published in Poland.




Hingorani, K.S., et al. “COVID-19 and the brain.” Trends in Cardiovascular Medicine. Volume 32, Issue 6, 2022.

Finsterer, J. et al. “Ischemic stroke in 455 COVID-19 patients.” Science Direct, Volume 77, January-December 2022

Crunfli, F. et al. “Morphological, cellular, and molecular basis of brain infection in COVID-19 patients.” PNAS, August 11, 2022.


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