Objective: To compare the prevalence of fatigue in patients with Parkinson's disease (PD) with that in healthy elderly people and to explore the suggestion that fatigue is an independent symptom of PD.
Design: Questionnaire survey.
Setting: Community-based population.
Patients and control subjects: 233 patients derived from a prevalence study in the county of Rogaland, Norway and 100 healthy elderly people with the same age and sex distribution as the patients with PD.
Main outcome measure: A score for fatigue was obtained by combining the results from the rating scale for low energy in the Nottingham Health Profile (NHP) with the results obtained from a 7-point scale devised to evaluate fatigue.
Results: 44.2% of the patients with PD and 18% of the healthy elderly control subjects reported fatigue. Fatigue was associated with depression, dementia, disease severity, disease duration, levodopa dose, and the use of sleeping pills. In a multivariate analysis, only depressive symptoms reached statistical significance. The prevalence of fatigue in patients with PD who were not depressed, demented, or had a sleeping disturbance was similar to that found in the total PD population.
Conclusion: Fatigue is a common symptom in PD. Although fatigue correlated with depressive symptoms, patients with PD who did not have depression, dementia, or sleep disturbances also reported a high prevalence of this symptom. This supports the hypothesis that fatigue is an independent symptom of PD overlapping with, but not causally related to, the concurrence of depressive symptoms.