Post-COVID-19 syndrome refers to a multisystem disorder that occurs after a SARS-CoV-2 infection. Symptoms are multifaceted and often neurological in nature. Post-COVID-19 affects about 10-15% of all COVID-19 infected, which in some cases can be severely debilitating. Diagnostic and therapeutic options are currently still limited. We want to investigate the long-term course, risk factors and biomarkers of Post COVID-19 syndrome to better understand the disease development and to provide starting points for future therapies. To this end, we examine patients in detail by using memory performance tests and questionnaires in parallel to brain imaging, blood and microbiome analyses.