Fatigue in Parkinson disease: an integrative review.

Fatigue, one of the most prevalent and underassessed nonmotor symptoms in patients with Parkinson disease (PD), is reported to be a major cause of disability and reduced quality of life. The purpose of this review was to systematically examine the scientific literature and report how fatigue is defined and measured and what interventions are used to treat it. A synthesis of the current literature will expose the current state of the science of fatigue in PD, propose areas for future research, and offer practice implications. An integrative review of the literature was conducted. The electronic databases CINAHL, Psychinfo, and PUBMED were searched using the keywords "Parkinson's disease," "fatigue," "definition," "mental fatigue," "physical fatigue," "measurement," "interventions," "treatment," and "methylphenidate." One hundred fourteen articles were found. Nineteen studies met review criteria. No universal definition of fatigue in PD was found, making it difficult to measure. However, central, physical, mental, and peripheral fatigues were described. Six scales were found that measure fatigue in PD; only one specific to PD, the Parkinson Fatigue Scale, measured physical fatigue. Seven studies reported interventions to treat fatigue and were categorized as medication, exercise, and alternative interventions. None of these interventions had a significant effect on fatigue. Findings showed that (a) there is a lack of a universally accepted definition of fatigue because of its subjective nature, (b) existing fatigue measurement tools do not measure all types of fatigue in PD, and (c) no intervention had a significant effect on fatigue. There is a need to define and explore fatigue further using qualitative methods. Further development of instruments to measure fatigue in women, younger onset, and older adults with PD is needed. A focus on person-centered interventions to reduce fatigue in patients with PD is a research priority.