COVID-19 Prevalence and Cognitive Deficits in Neurological Patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is spreading in nearly every country in the world. Patients with coronavirus disease 2019 (COVID-19) typically present with cough, fever and respiratory illness. In another coronavirus (SARS-COV-1) causing the SARS outbreak in 2002 to 2003, neurons have been found to be highly susceptible for infection and the virus can cause extensive neuronal damage with only minimal respiratory affection. Similar to SARS-CoV-1, COVID-19 virus exploits the angiotensin-converting enzyme 2 (ACE-2) receptor to gain entry and infect cells. Both glial and neurons express ACE-2 receptors and makes them potential targets, however the neurotropic potential in humans remain largely undescribed. Neurological manifestations of COVID-19 have only been sporadically described in single or short series of case reports together with a case of COVID-19 RNA in the cerebrospinal fluid.

Loss of smell (anosmia) may be a presenting symptom in COVID-19. Interestingly, in a study from Italy anosmia was present in 19,4% and not typical accompanied by nasal obstruction, rhinitis or sinusitis, making direct damage and invasion of the olfactory nerve more likely. A Chinese study have found that 36.6% of COVID-19 patients experience neurological symptoms and that severely affected COVID-19 patients reported more neurological symptoms.

In general, neurological manifestations to viral disease may occur as a direct result of viral invasion and damage to either the central or peripheral nervous system or from an immune mediated neurological damage either during (para) or after (post) the viral infection. Furthermore, the inflammation in itself can increase the risk of arterial thrombosis and thus ischemic stroke.

Early reports from Italy stresses the need to pay attention to neurological symptoms, as they are often neglected due to the systemic and respiratory impairment. Further, concerning reports from the Center for Disease Control (CDC) in USA, have estimated that out of COVID-19pos patients up to 46.5% may be asymptomatic/pre-symptomatic and 17,5% never develop classical COVID-19 symptoms. The COVID-19 infection is likely to be missed if patients present with symptoms from another organ system. Moreover, it poses a transmission risk for other admitted patients and healthcare workers and a risk that a possible association between e.g. neurological symptoms/diseases and a COVID-19 infection are missed. The role and presence of COVID-19 infection in patients presenting with acute neurological symptoms is currently unknown.