S100B and chronic obstructive pulmonary disease: The MMSE score was positively associated with PaO2 (r = 0.59, P < 0.01) and negatively correlated with serum S100B concentration ((r = −0.40, P < 0.05) in the mild-to-moderate COPD group, while it was positively associated with PaO2, SaO2 and FEV1 (r = 0.46, P < 0.01; r = 0.37, P < 0.01; r = 0.35, P < 0.05, respectively) and negatively correlated with S100B (r = −0.31, P < 0.05) in the severe COPD group (Figure 4).