This is Your Brain on COVID

By Chris Gabriel

The COVID-19 pandemic has shifted the way we live our lives and has been a driving force behind global policy since its emergence in late 2019. Some brush off COVID-19 as nothing but another flu or common cold, while others can recount stories and memories of a disease far more devastating. Though infection occurs primarily in the respiratory system, there are acute and long-term symptoms that can persist longer than 30 days after infection (Al-Aly et al., 2021). The virus can spread and cause damage all across the body, even reaching the nervous system. Perhaps you know someone who lost their sense of smell or experienced ‘brain fog’ while infected. Given that COVID-19 can infect the nervous system, it’s natural to ask how commonly neurological symptoms occur in COVID patients and how severe and long-lasting those symptoms might be.

These studies indicate that COVID-19 can broadly increase the likelihood of acquiring a number of neurological disorders and changes.


COVID-19 is caused by the SARS-CoV-2 virus and results in a variety of symptoms that affect the respiratory system as well as other organ systems in the body. In vitro evidence suggests that peripheral neurons could be susceptible to direct infection by the virus (Lyoo et al., 2022). But what types of neurological symptoms can you get from COVID-19? Large-scale analyses of outcomes after COVID-19 infection showed that patients were more likely to experience new symptoms including neurological and neurocognitive disorders, headaches, sleeping disorders, anxiety disorders, and stress-related disorders (Al-Aly et al., 2021). Patients who survived the first 30 days of COVID were also more likely to experience a stroke, memory problems (including Alzheimer’s disease), peripheral nerve disorders, migraines, seizure disorders, and movement disorders compared to control patients who were not infected (Xu et al., 2022). Even in mild cases of COVID-19, there are reductions in grey matter thickness, increases in inflammatory markers around the olfactory regions of the brain, and reduction in brain size when looking at changes after patients caught COVID-19 (Douaud et al., 2022). These studies indicate that COVID-19 can broadly increase the likelihood of acquiring a number of neurological disorders and changes.

How often does COVID-19 successfully attack the nervous system? And does it matter which variant you catch? The answers are essential in order to evaluate how concerning these side effects should be. Neurological symptoms occur in around 1/3 of hospitalized COVID-19 patients. The risk of acquiring these symptoms scales with the severity of SARS-CoV-2 infection, and symptoms can still emerge in the months following disease onset (Mao et al., 2020). One study found that incidence of a neurological or psychiatric diagnosis in the 6 months following infection was 33% for COVID-19 patients, with 13% of those being first-time diagnoses. These rates were higher for COVID-19 patients than for patients with other respiratory diseases (Taquet et al, 2021). Furthermore, disease severity was found to correlate with nervous system issues for COVID-19.

Clearly, the risk to your nervous system involved with SARS-CoV-2 infection is greater than comparable common infections.

As COVID-19 is commonly compared to the flu virus, it can be useful to compare neurological outcomes from infections by both viruses. One retrospective study of 236,379 patients with COVID-19 found that hazard rates (i.e., likelihood of dying) for neurological symptoms were significantly higher for those who caught COVID-19 versus influenza for all diagnoses except parkinsonism and Guillain-Barré syndrome (Taquet et al., 2021). Hazard rates for all neurological diagnoses were also higher for COVID-19 than for general respiratory infections. This indicates that COVID-19 may cause neurological damage beyond any influenza or common respiratory virus. Clearly, the risk to your nervous system involved with SARS-CoV-2 infection is greater than comparable common infections.

Although COVID-19 poses a risk to your nervous system, we have seen that severe neurological disease is relatively rare, especially given that vaccines mitigate the overall severity of the disease (Taquet et al., 2021; Xu et al., 2022). However, as of November 2022, over 630 million people have caught COVID-19 since the start of the pandemic, and there are over 6.5 million fatalities related to the disease (World Health Organization, 2022). It’s clear that this virus has had a major impact on our communities and continues to pose an ongoing threat to our health. The ability to cause long-lasting damage to the nervous system is just one aspect that sets COVID-19 apart from similar infections, and we don’t currently understand the full implications of these symptoms on one’s long-term health. Staying informed about the disease can help you mitigate your own risk and stay safe as we continue to deal with this virus for the foreseeable future.

Staying informed about the disease can help you mitigate your own risk and stay safe as we continue to deal with this virus for the foreseeable future.

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Written by Chris Gabriel
Illustrated by Federica Raguseo
Edited by Rebeka PopovicLauren Wagner, and John Zhou

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References
Al-Aly, Z., Xie, Y., & Bowe, B. (2021). High-dimensional characterization of post-acute sequelae of COVID-19. Nature, 594(7862), Article 7862. https://doi.org/10.1038/s41586-021-03553-9

Douaud, G., Lee, S., Alfaro-Almagro, F., Arthofer, C., Wang, C., McCarthy, P., Lange, F., Andersson, J. L. R., Griffanti, L., Duff, E., Jbabdi, S., Taschler, B., Keating, P., Winkler, A. M., Collins, R., Matthews, P. M., Allen, N., Miller, K. L., Nichols, T. E., & Smith, S. M. (2022). SARS-CoV-2 is associated with changes in brain structure in UK Biobank. Nature, 604(7907), Article 7907. https://doi.org/10.1038/s41586-022-04569-5

Dunai, C., Collie, C., & Michael, B. D. (2022). Immune-Mediated Mechanisms of COVID-19 Neuropathology. Frontiers in Neurology, 13. https://www.frontiersin.org/articles/10.3389/fneur.2022.882905

Lyoo, K.-S., Kim, H. M., Lee, B., Che, Y. H., Kim, S.-J., Song, D., Hwang, W., Lee, S., Park, J.-H., Na, W., Yun, S. P., & Kim, Y. J. (2022). Direct neuronal infection of SARS-CoV-2 reveals cellular and molecular pathology of chemosensory impairment of COVID-19 patients. Emerging Microbes & Infections, 11(1), 406–411. https://doi.org/10.1080/22221751.2021.2024095

Mao, L., Jin, H., Wang, M., Hu, Y., Chen, S., He, Q., Chang, J., Hong, C., Zhou, Y., Wang, D., Miao, X., Li, Y., & Hu, B. (2020). Neurologic Manifestations of Hospitalized Patients With Coronavirus Disease 2019 in Wuhan, China. JAMA Neurology, 77(6), 683–690. https://doi.org/10.1001/jamaneurol.2020.1127

Taquet, M., Geddes, J. R., Husain, M., Luciano, S., & Harrison, P. J. (2021). 6-month neurological and psychiatric outcomes in 236 379 survivors of COVID-19: A retrospective cohort study using electronic health records. The Lancet Psychiatry, 8(5), 416–427. https://doi.org/10.1016/S2215-0366(21)00084-5

World Health Organization. (2022, October 7). “WHO Coronavirus (COVID-19) Dashboard” Retrieved from https://covid19.who.int/

Xu, E., Xie, Y., & Al-Aly, Z. (2022). Long-term neurologic outcomes of COVID-19. Nature Medicine, 1–10. https://doi.org/10.1038/s41591-022-02001-z

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