The damage to the dopamine nerve endings was present in people who had been living with long COVID for up to 4.6 years. People with long COVID had lower levels of a tracer that binds to dopamine nerve endings than healthy people. Healthy people who had been infected with COVID-19 had fewer dopamine nerve endings than healthy people who had not been infected with the virus. Some people with long COVID might respond to "treatments which either increase the density of dopamine nerve terminals or improve the release of dopamine by the remaining dopamine nerve terminals", said Meyer. "We need to find biological changes in long COVID that plausibly account for symptoms, and then develop treatments to address the biological changes in people with long COVID who have these symptoms," said Meyer.