Figure 2.
Correlation between changes in the diurnal rhythm of cortisol (δ-cortisol slope and δ-cortisol p.m. minimum) and the development of fatigue (δ-fatigue) in control and IFN-α-treated subjects. Change in multidimensional fatigue inventory (MFI) total scores between visit 1 and 2 were significantly correlated with the change in cortisol slope (r = 0.43, P < 0.05) (a). Change in MFI total scores between visit 1 and 2 were also correlated with the change in minimum p.m. plasma concentrations (r = 0.49, P < 0.01) (b). Increases in MFI scores were correlated with flattening of the cortisol slope and increases in minimum p.m. plasma cortisol concentrations. Similar relationships were found between changes in cortisol slope and p.m. cortisol minimum and depression as measured by the Montgomery–Asberg depression rating scale.