Research published on Tuesday contended that neurological effects, unlike other symptoms, can persist for more than a year. The study, published in the journal Annals of Clinical and Translational Neurology, is the longest follow-up study of the neurological symptoms among long Covid patients who were never hospitalized for Covid. Those neurological symptoms include brain fog, numbness, tingling, headache, blurred vision, tinnitus, and fatigue, and are the most frequently reported for the illness.
A follow-up research found that 85% of the patients had at least four neurological problems even after six weak of their infections.
Most neurological symptoms persisted after an average of 15 months, and many reported that the symptoms had not gone away completely though the effect is wearing out.
“A lot of those patients still have difficulties with their cognition that prevent them from working like they used to,” said a study co-leader, Dr. Igor Koralnik, the chief of neuro-infectious diseases and global neurology at Northwestern Medicine, who oversees the Neuro COVID-19 Clinic.
The study also contended that other problems like blood pressure variation and gastrointestinal problems increased over time, unlike the loss of taste and smell, which tended to improve.
Dr. Avindra Nath, the clinical director of the National Institute of Neurological Disorders and Stroke at the National Institutes of Health, said that one hypothesis is that those symptoms are the result of the body’s inflammatory response to coronavirus, and viral infections affect the brain.
The inflammation is meant to attack the invading virus, but it also damages brain cells and neurons in the process. SARS-CoV-2, the virus that causes Covid, triggers a particularly strong inflammatory response, he said.
“Covid is probably the most severe respiratory illness we have ever had, so it’s no surprise that we are seeing long-term effects from it,” Nath said.
The long time that those symptoms can last is not normal even though immune response contributes to some symptoms that the patients experience, like fatigue. More time is needed for researchers to test and conclude the reason for the phenomena, but their search for biomarkers has yielded no results so far.