The consequences of the past coronavirus COVID-19 can envenom the quality of a person's life even more than six months after the illness. The virus can affect one or more important organs, and cause serious diseases. Scientists are discovering more and more dangers from COVID-19.
Coronavirus and Alzheimer's disease
The Cleveland Clinic led a study in which scientists identified the mechanisms. With their help, the coronavirus COVID-19 can lead to dementia that is similar to Alzheimer's disease. The study results indicated a partial overlap between COVID-19 and the brain changes that are common in Alzheimer's disease. These findings can help guide risk management and treatment strategies for COVID-19-associated cognitive impairment.
Using artificial intelligence, scientists studied datasets of patients with Alzheimer's disease and COVID-19. They measured the proximity between genes and proteins from SARS-CoV-2 patients and those genes and proteins associated with several neurological diseases. They also analyzed the genetic factors that enabled COVID-19 to infect tissues and brain cells. Indeed, SARS-CoV-2, the virus that causes COVID-19, can have lasting effects on brain function. However, it is not yet well understood how the virus leads to neurological problems.
"While some studies suggest that SARS-CoV-2 infects brain cells directly, others found no evidence of the virus in the brain," Feixiong Cheng, Ph.D., assistant staff in Cleveland Clinic’s Genomic Medicine Institute and lead author on the study, says.
While the researchers found little evidence that the virus targets the brain directly, they found a close network relationship between the virus and genes/proteins. The latter are associated with several neurological diseases, most notably Alzheimer's disease. To explore this further, they investigated the potential link between COVID-19 and neuroinflammation and brain microvascular injury in the brain that are hallmarks of Alzheimer's disease.
"We discovered that SARS-CoV-2 infection significantly altered Alzheimer’s markers implicated in brain inflammation and that certain viral entry factors are highly expressed in cells in the blood-brain barrier," explained Dr. Cheng.
According to him, these data show that the virus may impact several genes or pathways involved in neuroinflammation and brain microvascular injury. And this, in turn, can lead to cognitive impairment similar to Alzegimer's. The researchers found that individuals with the allele APOE E4/E4, the greatest genetic risk factor for Alzheimer’s, had decreased expression of antiviral defense genes. This could make these patients more susceptible to COVID-19.
COVID-19 and Guillain-Barre syndrome
Researchers at the University of Birmingham found out that coronavirus can lead to the development of Guillain-Barre syndrome. In this syndrome, the human immune system affects part of the peripheral nervous system. Guillain-Barre syndrome can lead to muscle weakness and sensory anesthesia in the legs and arms, preceded by a bacterial or viral infection.
The study found out that the antibodies produced in people who have had coronavirus resemble those that lead to heart and skin diseases. Early data suggest that SARS-CoV-2 infection can trigger long-term autoimmune complications, and there are reports that SARS-CoV-2 infection is being associated with a number of autoimmune disorders including Guillain-Barre syndrome.
In the course of the study, non-COVID patients displayed a diverse pattern of autoantibodies. The COVID-19 groups had a more restricted panel of autoantibodies (a type of protein produced by the immune system and targeted against a person's own proteins and can cause autoimmune disorders ). The authors also found out that those with more severe COVID-19 were more likely to have an autoantibody in their blood.
"The antibodies we identified are similar to those that cause a number of skin, muscle and heart autoimmune diseases. We don’t yet know whether these autoantibodies are definitely causing symptoms in patients and whether this is a common phenomenon after lots of infections or just following COVID-19. These questions will be addressed in the next part of our study." Professor Alex Richter, of the University of Birmingham, reported.
Coronavirus and stroke
Complications of Covid-19 can include delirium, brain inflammation, stroke, and nerve damage, according to a study by neurologists at University College London. Scientists have diagnosed disseminated encephalomyelitis , an inflammatory disease that affects the myelin sheath of brain and spinal cord nerve cells, in more than 40 patients with COVID-19.
The coronavirus attacks the brain differently from other viruses, scientists believe. SARS-CoV-2 was not detected in the cerebrospinal brain fluid of any of the patients tested. This suggests that the virus is not directly attacking the brain. In some patients, the brain inflammation was likely triggered by the immune response to COVID-19, rather than the virus itself.