Age, Depression, Other Factors Linked to Fatigue Progression, Study Finds

Fatigue increases over time in people with Parkinson’s disease and is associated with several factors, including sex, age, depression symptoms, and higher cognitive function, a study has found.

The results of the longitudinal study, “Progression of fatigue in Parkinson’s disease – A nine-year follow-up,” were published in the European Journal of Neurology.

Fatigue, or unrelenting exhaustion, is one of the most common and most disabling symptoms among people with Parkinson’s and has a significant impact on patients’ quality of life. However, the biological mechanisms underlying this symptom are poorly understood.

“Though highly disabling, the pathogenesis [disease development] and evolution of fatigue in Parkinson’s disease is largely unknown, and no sufficiently documented treatment currently exists,” the researchers wrote.

To fill this gap, researchers based at Sorlandet Hospital, in Norway, assessed the development of fatigue in patients from the Norwegian ParkWest project, focusing on the first nine years following the participants’ diagnoses.

The study included 191 patients newly diagnosed with Parkinson’s and 170 age- and sex-matched healthy participants who served as controls. At the nine-year follow-up, only 104 patients and 113 controls had data available, due to either death or withdrawal from the study.

Fatigue was measured at the beginning of the study (baseline), and every other year up to nine years, using the Fatigue Severity Scale (FSS). Standard evaluations also were performed, such as self-assessment forms and physical examinations by a neurologist. Disease severity was assessed by the Unified Parkinson Disease Rating Scale (UPDRS).

Depression symptoms, cognition, and daytime sleepiness also were assessed.

At the beginning of the study, 112 of 191 patients (58.6%) had clinically significant fatigue, compared with 34 of 170 healthy controls (20.0%). After nine years of follow-up, 76 out of 104 patients (73.1%) had the symptoms, compared with 30 out of 113 controls (26.5%).

Parkinson’s patients had a 25% risk of developing fatigue after nine years, when compared with baseline. They also had a significantly higher risk of experiencing it at least once during the nine years of follow up when compared with the healthy controls (94.8% vs. 64.7%). Accordingly, the participants with Parkinson’s also had a higher risk of experiencing persistent fatigue (10.5% vs. 4.1%).

The proportion of affected patients increased with time, though many individuals displayed a non-persistent pattern of fatigue during the course of the follow-up. The researchers noted that the findings demonstrated dynamic changes in the condition.

Factors such as female sex, age, and comorbidity — the presence of one or more additional health conditions — at the study’s start were significantly associated with the condition. Other factors, including depression symptoms, higher cognitive function, and dependency in activities of daily living, were associated with increased fatigue during follow-up.

Finally, the researchers found a small but statistically significant association between lower symptom levels and being medicated with dopamine agonists, which are used to overcome dopamine loss and manage symptoms. This association was not found in other groups of Parkinson’s medications.

“The association between fatigue and other non-motor symptoms that may be more susceptible to treatment could yield benefits in the management of fatigue,” the researchers wrote.

“This study is thus a contribution to understanding the multifaceted issue of fatigue in Parkinson’s. Further studies are needed to verify the results and, if possible, to explore direct or indirect treatment options,” they concluded.