COVID-19 can elicit a severe immune response that triggers a storm of proteins called cytokines, which amplify inflammation throughout the body. Long-term inflammation can promote cognitive decline and neurodegenerative diseases.
Because COVID-19 affects respiration, it can starve the brain of oxygen, as seen in autopsy data from Finland. COVID-19 also increases the risk for blood clots for up to six months, which can cause strokes that deprive the brain tissue of oxygen.
Some scientists even fear that COVID-19 survivors could be at higher risk for Alzheimer’s disease, based on evidence for a protein called beta-amyloid in the brains of younger patients who died of COVID-19.
Several studies also show evidence of the SARS-CoV-2 virus invading the brain. A study by the U.S. National Institutes of Health illustrates how SARS-CoV-2 can spread well beyond the lungs and the respiratory tract. This suggests that the inability of the immune system to clear the virus from the body could be a potential contributor to long COVID symptoms, including brain fog.