A longitudinal study on fatigue, depression, and their relation to neurocognition in multiple sclerosis

Aims: Fatigue and depression are two common syndromes in patients with multiple sclerosis (MS), but their inherent relation and causes are still under debate. Method: With a longitudinal design we analyzed their development over a period of one year and their relation to the clinical status, brain atrophy, and neurocognitive performance at the beginning of the study. Forty patients with relapsing-remitting MS were included and were assessed for fatigue and depressive mood, clinical status, neurocognitive performance, and brain parenchymal fraction. Results: Regression analyses showed that changes in fatigue are predicted by fatigue status and gait performance at Visit 1. Changes in depressive mood are predicted by executive functioning, memory performance, and depressive mood at Visit 1. Additional evidence for a dissociation between fatigue and depression was found when patient groups suffering at Visit 2 from fatigue or not and having a depressed mood or not were contrasted. Conclusion: We conclude that although fatigue and depressive mood share many features, they do not behave similarly in the course of relapsing-remitting MS. Our results fit the proposal that fatigue is a reversible syndrome similar to sickness behavior, and that depressive mood is at least partially related to neurodegeneration.