Researchers have finally uncovered a multiorgan pathway with important implications for the pathogenesis of Long COVID. Several hypotheses have been proposed to explain the causes of Long COVID. These include the presence of a viral reservoir long after initial infection; chronic inflammation, development of antibodies (as a result of anti-viral responses) that mistakenly target and damage a person’s own tissues or organs; platelet dysfunction and increased tendency to form blood clots inside blood vessels; and finally autonomic nervous system dysfunction in which the nervous system cannot control processes like heart rate or blood pressure. In addition, people suffering from Long COVID also exhibit reduced levels of peripheral serotonin, which prevents the activity of the vagus nerve system, which transmits signals between the body and the brain, thus impairing hippocampal responses and memory.
A study published recently in the journal Cell, researchers from the University of Pennsylvania, Philadelphia, who led the study, have found reduced levels of serotonin, a neurotransmitter, being associated with Long COVID. Memory problems, brain fog, and the inability to focus on tasks that people with Long COVID seem to suffer from might be due to reduced serotonin, the authors say. They followed a cohort of more than 1,500 individuals with Long COVID and characterised their spectrum of symptoms.
