This article was originally written by Maya Nava and published on Scientist.com.
The neurological consequences of SARS-CoV-2 infection are not yet fully understood. When a virus enters the human body, the immune system sends out inflammatory cells to fight the infection, and also produces antibodies. The resulting inflammation can ultimately cause cognitive impairments known as brain fog, which is recognized as a symptom of long COVID.
Scientists propose that microglia cells are also responsible for causing this extended inflammation. The primary function of microglia cells is to “clean up” the brain (i.e., taking in and breaking down dead cells and materials), but their job changes when a virus or bacteria disrupts the body. When triggered, microglia cells emit signals to cause inflammation within brain tissue, and can also alter their shape and multiply, which can result in cell death and inhibit the production of new neurons within the hippocampus (Figure 1) . Short term deterioration may occur when the hippocampus is affected by COVID, and injury to the hippocampus may explain why some individuals experience brain fog following a SARS-CoV-2 infection .