Neurotropic effects of respiratory viral infections: mental and neuropsychological aspects

Abstract

The review is devoted to the problem of neurological complications that result from respiratory viral infections due to viral invasion to the central and peripheral nervous systems. Psychoneurological consequences after the disease of COVID-19 are considered separately. Viral pathogens can enter the central nervous system (CNS) in various ways, including through hematogenous infection of the endothelium (the “Trojan horse” mechanism) as well as through peripheral nerves or olfactory sensory neurons. The latter route is mostly used by respiratory viruses, such as coronaviruses (CoV), which enter the body intranasally because the olfactory nerve connects the nasal epithelium with the olfactory bulb — the way to the CNS. CoV in the human brain can cause long-term effects associated with the development or exacerbation of chronic neurological diseases, such as multiple sclerosis. Coronavirus COVID-19, which causes coronavirus disease, can provoke long-term outcomes after recovery, such as psychiatric symptoms and cognitive impairment, which are detected by cognitive screening. In the post-COVID period, patients demonstrated poor cognitive performance in the areas of attention, performance, and memory as well as increased levels of depression, anxiety, post-traumatic stress, fatigue, and sleep disturbances. These effects should be considered as possible post-viral disorders that require special diagnosis and appropriate treatment. Significant heterogeneity of applied approaches and methods hinders the comprehensive characterization of cognitive functions in specific areas since the studies often excluded people with previous cognitive impairment. Nevertheless, most studies indicate some degree of cognitive impairment in patients with COVID-19. Although the rates vary, a significant proportion of survivors show poor cognitive performance in the areas of attention, performance, and memory. These results have several important implications for further research, clinical management, and treatment of those who have experienced COVID-19.