The Neurological Impact of Testing Positive for COVID-19

How the coronavirus might impact brain and behavior.

Posted Jun 23, 2020

Seven months has passed now since the novel coronavirus (SARS-CoV-2) was first identified in Wuhan, China, in December 2019 [1]. At the start of the new year, the World Health Organization began investigating cases of pneumonia in Wuhan associated with the virus, and by mid-January, the first case was confirmed outside of China, in Thailand. By the end of the month, the outbreak was confirmed as a Public Health Emergency of International Concern [2].

However, it was not until about a month and a half later, in mid-March, that countries began to adopt quarantine rules and implement social distancing strategies as a means of controlling the spread of the virus. For many, this has marked a fundamental change in how they live their lives, and has led some to speculate that humans could be living with the virus for many years to come [3].

This will have a profound impact on human behavior.

We are already seeing the warnings and cautions on our mental health by having to isolate and abide by quarantine regulations, such as increased depression and anxiety [4], but there is increasing evidence that there could be in addition neurological and behavioral implications of testing positive for the virus.

Even though it is known that the Coronavirus can cause respiratory distress, there is a growing body of evidence for neurological symptoms for those who test positive. Coolen et al. [5] reported on the autopsy results of 19 decedents, who had all passed after testing positive for COVID 19, and they found evidence for hemorrhagic and encephalopathy related brain lesions that could have been virus induced. Coolen et al. point out that SARS-CoV-2 enters the human body by using the angiotensin-converting enzyme 2 (ACE 2) as a cellular entry point. Even though this protein lines airway epithelia and lung parenchyma, it is also present in glial cells, neurons, and brain cell nuclei [5]. ACE 2 would be a candidate for allowing COVID 19 into the central nervous system.

Evidence for neurological symptoms, albeit weak, was also found by Helms at al. [6], when investigating COVID 19 patients in France. Eight of fifty-eight patients demonstrated neurologic symptoms upon admission to the ICU after presenting with acute respiratory distress syndrome due to the virus. These symptoms included agitation and dysexecutive syndrome, which is characterized by a loss of executive functioning over things like planning, abstract thinking, and control over behavior [7]. This sets the stage for the COVID 19 virus to interfere with our personalities and in the faculties that allow us to exert some control over our lives.

A further remarkable finding by Coolen et al. is that 4 decedents had asymmetric olfactory bulbs, without any further downstream anomalies. The olfactory bulbs are the interface of where aromatic molecules from the outside world stimulate the neurons in our noses, which results in our sense of smell. Anosmia, which is the loss of our ability to smell, has been commonly reported as a symptom of COVID 19 infection [8]: Misshapen olfactory bulbs could be one of the reasons why. Another team of researchers were able to perform an MRI on a patient who tested positive, and they found cortical hyperintensity in the right rectal gyrus, which is also an area involved in olfaction [9]. Differences in tissue shape and in electrochemical activity could be undermining the ability to smell for these patients.

There is currently no data on whether or not anosmia is reversible once experienced for patients who test positive for the virus. The loss of smell is likely to be highly stressful for COVID 19 patients (in addition to all of the other symptoms), as this will impact their life in serious ways. The ability to sense odors provides us with important warnings regarding food or the presence of harmful materials, but it also allows for a higher quality of life by easily maintaining hygiene standards, and enjoying pleasant odors, such as the smells of our loved ones [10]. The loss of an entire sensory system is a damaging and traumatic experience, and could result in the need to seek counseling and adaptive coaching.

Regrettably, due to the increased strain on medical facilities, the number of MRIs and CT scans have dropped considerably in both emergency departments and inpatient facilities [11]. However, the growing body of evidence for neurological implications and central nervous system influence necessitates the need to use all of our contemporary tools for neurological analysis to understand the passage and influence of the virus once a person becomes infected. The state of the research at the moment is mostly observational case studies, which are hampered by many confounding variables.

If we are to live with the virus, we will need to know how the virus will live with us. The fact that it can enter into both our respiratory and central nervous systems makes it a considerable threat, and adds even more stress to already over-burdened global public health systems.

References

1. The novel coronavirus outbreak: what we know and what we don’t. Cell 180(6):1034–1036 (2020). https ://doi.org/10.1016/j. cell.2020.02.027

2. https://www.who.int/emergencies/diseases/novel-coronavirus-2019/events-as-they-happen

3. https://www.discovermagazine.com/health/could-we-be-living-with-covid-19-forever

4. Fischer, R., Karl, J., Bortolini, T., Zilberberg, M., Robinson, K., Rabelo, A. L. A., ... & Mattos, P. (2020). Rapid review and meta-meta-analysis of self-guided interventions to address anxiety, depression and stress during COVID-19 social distancing.

5. Coolen, T., Lolli, V., Sadeghi, N., Rovai, A., Trotta, N., Taccone, F. S., ... & Naeije, G. (2020). Early postmortem brain MRI findings in COVID-19 non-survivors. medRxiv.

6. Helms, J., Kremer, S., Merdji, H., Clere-Jehl, R., Schenck, M., Kummerlen, C., ... & Anheim, M. (2020). Neurologic features in severe SARS-CoV-2 infection. New England Journal of Medicine.

7. Baddeley, A., & Wilson, B. (1988). Frontal amnesia and the dysexecutive syndrome. Brain and cognition, 7(2), 212-230.

8. Vaira, L. A., Salzano, G., Deiana, G., & De Riu, G. (2020). Anosmia and ageusia: common findings in COVID‐19 patients. The Laryngoscope.

9. Politi, L. S., Salsano, E., & Grimaldi, M. (2020). Magnetic resonance imaging alteration of the brain in a patient with coronavirus disease 2019 (covid-19) and anosmia. JAMA Neurology.

10. Boesveldt, S., Postma, E. M., Boak, D., Welge-Luessen, A., Schöpf, V., Mainland, J. D., ... & Duffy, V. B. (2017). Anosmia—a clinical review. Chemical senses, 42(7), 513-523.

11. Jain, R. (2020). Evolving Neuroimaging Findings during COVID-19. AJNR. American Journal of Neuroradiology.