Fatigue in early Parkinson's disease: the Norwegian ParkWest study

Background and purpose: Fatigue is a common and disabling non-motor symptom in Parkinson's disease (PD). The pathogenesis is unknown, and the treatment options are limited. The aim of the present study was to investigate the development of fatigue during the first year after diagnosis. Methods: The study design was a prospective, controlled population-based longitudinal cohort study, comprising 181 de novo, drug-naive patients with PD and 162 control participants. PD was diagnosed according to the Gelb criteria. Fatigue was assessed by the Fatigue Severity Scale (FSS). Both groups were assessed for fatigue at baseline and after 1 year. Results: Patients reported more fatigue than the control subjects at baseline and at the 1-year follow-up evaluation. The FSS scores in the patient group improved from a mean score of 4.4 (SD 1.6) to 4.0 (SD 1.6). Patients with fatigue at baseline received higher doses of dopaminergic medication during follow-up. Patients who received dopamine agonists improved slightly more than patients who received levodopa. A regression analysis did not show a correlation between an improvement in fatigue and a change in disease severity, depressive symptoms, sleep problems, apathy or cognitive impairment. Conclusion: Fatigue is a common symptom in PD, also in early, untreated patients. During the first year of observation, an improvement in the fatigue scores was found. The improvement could not be attributed to a change in disease severity or depressive symptoms. The results indicate a better effect of dopamine agonists than of levodopa. This may have implications for treatment in patients with PD-associated fatigue.