Encephalon 5: Viruses and Brain
Viruses are unavoidable organisms of life. We encounter them many times during our life. The biggest problem with viral infections is they often do not stay in the infected person and spread the other healthy people with tremendous speed as in pandemics or epidemics. Most of us become infected with these viruses and gain adaptive immunity. However, this is not always the case. Virus infection can cause destructive effects on the body and even lead to death. Unlike bacteria, viruses’ access is not limited only to internal systems. They often reach out to the brain due to their tiny structure. The viruses’ effects on the brain have always been a great mystery for the researcher.
An atypical form of brain inflammation, encephalitis lethargica, emerged simultaneously with the Spanish flu pandemic between 1915 and 1926. Baron Constantin von Enconomo, an Australian neurologist, studied victims’ brains and discovered that the lesions of the anterior hypothalamus neurons due to inflammation led to insomnia in patients (von Economo, K. 1917). This finding suggests the potential involvement of the Spanish flu virus in neuroinflammation.
Similarly, recent studies on animals revealed that the Epstein-Bars virus, a common herpes virus associated with the malignant and non-malignant conditions, causes inflammation in compact clusters of macrophages and surrounded by astrocytes. It has been reported that inflammation incidence increased in immunosuppressed animals (Hassani A. et al., 2021). The studies also indicate that the Epstein-Bars virus triggers multiple sclerosis, a most common immune-mediated disorder affecting the central nervous system (Lanz T. et al., 2022).
The ongoing COVID-19 pandemic is also brought lots of mystery to understanding the potential effects of coronaviruses on the brain. The reports clearly show strong evidence of brain-related abnormalities in COVID-19 patients. The recent findings suggest that the virus that caused the COVID-19 also changes the brain structure (Douaud G. et al., 2022). One of the most common symptoms for long COVID-19 patients is confusion, difficulty remembering things, slow thinking, and poor concentration (Zhao S. et al., 2022).
All this evidence suggests that viruses’ effects on the brain can be more destructive in immunocompromised conditions. Another mystery is whether the viruses’ effects on the brain are reversible in the post-disease period. There is still plenty of mystery that remains to be elucidated in viruses’ effects on the brain.
