Long COVID is associated with severe cognitive slowing: a multicentre cross-sectional study by Zhao, S, Martin, EM, Reuken, PA, Scholcz, A, Ganse-Dumrath, A, Srowig, A, Utech, I, Kozik, V, Radscheidt, M, Brodoehl, S, Stallmach, A, Schwab, M, Fraser, E, Finke, K, Husain, M