Objective: To explore relations of fatigue, physical disabilities, and depression in patients with multiple sclerosis (MS)
cross-sectionally and over time. Methods: Ninety-eight MS patients were interviewed twice at an interval of a year.
Relationships of physical and mental fatigue, and reduced activity and motivation with depression and physical disabilities were established cross-sectionally by regression analyses and longitudinally
by structural equation modelling. Results: Crosssectionally, physical fatigue was related with physical disabilities,
and mental fatigue was associated with depression. Prospectively, physical fatigue was a predictor of the physical disabilities of a year later. The reverse relationship of physical disabilities predicting the physical fatigue of one year later was, however, not significant, while depression predicted this physical fatigue and reduced activity of a year later. Depression did not predict the later mental fatigue nor was depression predicted by preceding
fatigue experiences. Conclusions: Fatigue in MS should be studied over time as relationships of fatigue with physical and
mental health change during the course of a year. Moreover, differentiating in fatigue experiences sheds light on the relationship
of fatigue with physical and mental health.