New research from Germany has found that the spike protein from the COVID-19 virus can remain in the brain long after the virus has cleared out, causing long COVID symptoms such as brain fog, cognitive decline, and memory problems. The researchers discovered the spike protein in the brain tissue of both animals and humans after death, suggesting that these virus fragments build up and trigger inflammation. Approximately 15% of COVID patients continue to experience long-term effects of the virus despite their recovery. The researchers propose that the spike protein can enter the brain via the skull’s niches and meninges, thin layers of cells that act as a buffer between the skull and the brain. The hope is that researchers can develop treatments that block one or more steps in this process and help people avoid long COVID brain issues. The report is concerning, as having the spike protein accumulate in structures right outside the brain and causing ongoing inflammation makes sense, triggering an immune response from the niche reservoir of immune cells that cause the inflammation associated with long COVID and the symptoms such as brain fog. Problems with thinking and memory after COVID infection are relatively common, and even people who had mild COVID illness can develop brain fog later. Researchers are blaming the spike protein and not the whole COVID virus as part of the study found SARS-CoV-2 virus RNA in some people after death and not in others. They also injected the spike protein directly into the brains of mice and showed it can cause cells to die. Future treatments are possible but will require an in-depth knowledge of the molecules dysregulated by the virus in the brain tissues. Tests for protein changes in the skull or meninges would be invasive but possible compared to sampling the parenchyma inside the brain. Even less invasive would be testing blood samples for altered proteins that could identify people most at risk of developing brain complications after COVID illness.
COVID may leave remnants in the brain