What Fatigue Means to Persons Living with Parkinson's Disease? A Qualitative Study

ABSTRACT

Background

Fatigue is one of the most prevalent non‐motor symptoms of Parkinson's disease (PD). Research is hampered by imprecise terminology and the lack of case definition criteria.

Objectives

To elicit the experiences of persons living with PD‐related fatigue and provide ecological validation for case definition criteria.

Methods

Qualitative interviews were conducted with 22 individuals and 4 focus groups, and analyzed using an inductive qualitative method.

Results

Six core themes emerged: (i) difficulty initiating and completing important tasks; (ii) desire for others to understand their fatigue experience; (iii) heterogeneity of experiences and descriptions of fatigue; (iv) complex relationships with other non‐motor symptoms; (v) variable self‐management strategies; and (vi) general alignment with proposed case definition criteria.

Conclusions

PD‐related fatigue impacts function, is subjectively distinguishable from other non‐motor symptoms, has heterogeneous descriptions, and may be mitigated by various self‐management strategies. Proposed case definition criteria appear ecologically valid and warrant further optimization and testing.

Fatigue is one of the most common and debilitating non‐motor symptoms of Parkinson's disease (PD).¹, ² Despite epidemiological studies suggesting the immense impact of fatigue in PD, research into this symptom has been hindered by multiple factors, including measurement and terminology issues. There is noted variability in how scales operationalize fatigue, with many scales making no distinction between fatigue and related constructs such as sleepiness.³ Another major barrier has been the lack of a consensus definition for PD‐related fatigue. In 2016, an international working group identified key areas to focus research efforts and proposed specific case definition criteria for PD‐related fatigue (Table 1).⁴, ⁵

TABLE 1.

Proposed criteria for diagnosis of Parkinson's disease‐related fatigue ⁵

Patients must report significantly diminished energy levels, or increased perceptions of effort that are disproportionate to attempted activities or general activity level. Symptoms must be present for most of the day, every day, or nearly every day during the previous month. In addition, patients must have 4 or more of the symptoms from section A as well as meet criteria in sections B, C, and D.

A. Symptoms

1. Symptoms may be induced by routine activities of daily living.

2. Symptoms may occur with little or no exertion.

3. Symptoms limit the type, intensity, or duration of activities performed by the patient.

4. Symptoms are not reliably relieved by rest or may require prolonged periods of rest.

5. Symptoms may be brought on by cognitive tasks or situations requiring sustained attention including social interactions.

6. Patients avoid rigorous activities due to fear of experiencing worsening of symptoms.

7. Mild to moderate exertion may induce a worsening of symptoms lasting hours to days.

8. Symptoms have a predictable diurnal pattern regardless of activities performed (eg worsening in the afternoon).

9. Symptoms are unpredictable and may have a sudden onset.

B. The patient experiences clinically significant distress or impairment in social, occupational, or other important areas of function as a result of fatigue.

C. There is evidence from the history and physical examination suggesting fatigue is a consequence of PD.

D. The symptoms are not primarily a consequence of comorbid psychiatric disorders (eg depression), sleep disorders (eg obstructive sleep apnea) or medical conditions (eg anemia, congestive heart failure).

This study aims to: (i) elicit the lived experiences of persons suffering from PD‐related fatigue to better understand phenomenology and refine terminology; and (ii) evaluate the alignment of proposed case definition criteria with patient experiences.

Methods

Study procedures and documents were approved by our local institutional review board. Verbal consent was obtained for focus group participants and written informed consent for individual interviews.

Recruitment

Participants were drawn from a larger quantitative cohort study that was investigating the prevalence and impact of visual and vestibular abnormalities in PD, including their impact on fatigue.⁶ This larger pool was, in turn, drawn from an academic tertiary care center and community support groups between June 2017 and August 2019. Individuals were included if they were English‐speaking, 45 to 90 years of age, diagnosis of PD confirmed by a neurologist, were ambulatory with or without an assistive device, able to provide informed consent, and reported symptoms of fatigue. Additionally, individual interview participants were excluded if they had another medical condition known to be associated with chronic fatigue. For individual interviews, we initially used convenience sampling, but switched to maximum variation sampling (purposefully recruiting participants based on characteristics of interest) to ensure diversity in terms of age, sex, and PD severity. Focus group participants were recruited using a convenience sample from local support groups.

To characterize our cohort, we collected demographic data, quality of life data using the Parkinson's Disease Questionnaire (PDQ‐39),⁷ and assessed motor symptom severity using the Movement Disorder Society Unified Parkinson Disease Rating Scale (MDS UPDRS).⁸ We assessed cognition using the Montreal Cognitive Assessment (MoCA)⁹ and fatigue severity using the Fatigue Severity Scale (FSS)¹⁰ and the Multidimensional Fatigue Inventory (MFI‐20).¹¹ To identify possible confounding non‐motor symptoms, we collected measures of sleepiness, apathy, and mood using the Epworth Sleepiness Scale (ESS),¹² Parkinson's Disease Sleep Scale (PDSS),¹³ Apathy Scale (AS),¹⁴ and the Hospital Anxiety and Depression Scale (HADS).¹⁵

Data Collection and Interpretation

Individual Qualitative Interviews

Semi‐structured qualitative interviews (see Appendix for guide) were conducted with 22 individuals in private rooms at a tertiary healthcare center. Interviews averaged 60 min.

Focus Group Interviews

Focus group interviews were conducted through PD support groups. Participants were informed of discussion themes before discussion. Focus groups lasted an average of 72 min and included topics beyond fatigue (reported in other manuscripts).

Analysis

Interviews were digitally recorded and transcribed. ATLAS.ti (Version 8, ATLAS.ti Scientific Software Development, Berlin, Germany) was used for analysis, including coding and theme development. An inductive qualitative analysis technique was used. Investigator triangulation was used to increase study validity.

Results

Participant Characteristics and Overview

Individual qualitative interview participant demographic and disease characteristics are summarized in Table 2. A total of 22 individuals were recruited for individual interviews. Twenty‐nine individuals (14 male; 15 female) were recruited for focus group sessions.

TABLE 2.

Qualitative interview participant characteristics

Sample size, n	22
Sex, n (%)
Female	6 (27%)
Male	16 (73%)
Age y, mean (SD)	72.3 (7.7)
Years of education, mean (SD)	16.2 (2.5)
Hoehn & Yahr, 29 n (%)
Stage I	1 (4.5%)
Stage II	18 (82%)
Stage III	2 (9%)
Stage IV	1 (4.5%)
MoCA (suggested cut‐point for PD‐related cognitive impairment ≤26), 30 mean (SD), range	25.9 (4.1), 16–30
Dementia, n (%)	1 (4.5%)
Deep brain stimulation surgery, n (%)	2 (9%)
PDQ‐39 Summary Index, mean (SD)	21.2 (11.4)
FSS total score (suggested cut‐point for moderate fatigue ≤36), 10 mean (SD)	38.4 (13.5)
MFI total score (cut‐point not defined), mean (SD)	58.1 (17.0)
MDS‐UPDRS motor subsection, mean (SD)	32.6 (11.0)
Proposed Case Definition Criteria, n (%)	15/22 (68%)
ESS (suggested cut‐off for excessive daytime sleepiness ≤8), 31 mean (SD)	9.6 (4.4)
PDSS, (suggested cut‐point for potential sleep disorder ≤82) 32 mean (SD)	103.5 (13.3)
AS (suggested cut‐point for apathy ≥14), 33 mean (SD)	12.5 (6.6)
HADS Anxiety score (suggested cut‐point <8), 34 mean (SD)	6.0 (3.7)
HADS Depression score (suggested cut‐point <8), 34 mean (SD)	5.0 (3.6)

AS, Apathy Scale; ESS, Epworth SLEEPINESS SCALE; FSS, Fatigue Severity Scale; HADS, Hospital Anxiety And Depression Scale; MDS‐UPDRS, Movement Disorder Society Unified Parkinson's Disease Rating Scale; MFI, Multidimensional Fatigue Inventory; MoCA, Montreal Cognitive Assessment; PDQ‐39, Parkinson's Disease Questionnaire; PDSS, Parkinson's Disease Sleep Scale.

Six core themes were identified through coding: (i) difficulty initiating and completing important tasks; (ii) desire for others to understand their fatigue experience; (iii) heterogeneity of experiences and descriptions of fatigue; (iv) complex relationships with other non‐motor symptoms; (v) variable self‐management strategies; and (vi) general alignment with proposed case definition criteria. See Table S1 for supportive quotes.

Theme 1: Difficulty Initiating and Completing Important Tasks

Patients were frequently frustrated by how fatigue limited their ability to initiate or complete important activities. Some participants described lacking sufficient energy to begin an activity, leading them postpone for a later time. Others explained needing time to collect more energy before attempting an activity or not having the stamina to perform activities for as long as they desired. These situations consistently caused frustration because of feelings of diminished productivity. Most participants did not describe a lack of motivation or disinterest for activities. Affected activities included those associated with daily living and those that brought participants a sense of meaning (reading, socializing with friends and family, pursuing hobbies).

Theme 2: Desire for Others to Understand their Fatigue Experience

Participants wanted others to better understand their experience and described feeling blamed or shamed for their fatigue, being labeled as “lazy,” “apathetic,” or “unwilling to participate.” Participants expressed frustration with these judgments, feeling they were unjust. Many of those interviewed wanted others to understand that their fatigue was because of PD and wished others knew fatigue symptoms were outside of their control.

Theme 3: Heterogeneity in Patients' Experiences and Descriptions of Fatigue

We found heterogeneity in the language used to describe the sensations or bodily experience of fatigue, the onset of symptoms, the intensity of symptoms, the duration of symptoms, and aggravating stimuli. The language used to describe the bodily sensations of fatigue symptoms included words such as “heaviness,” “fogginess,” and “tiredness.” Others used analogies to cars “running out of gas” or a computer slowing down. Some said fatigue came on “suddenly” or “like a wave,” whereas others described a gradual onset. Some reported waking up with fatigue symptoms, whereas many reported fatigue worsening throughout the day, especially in the afternoon.

Regarding the relationship of fatigue onset to diagnosis of PD, some participants felt fatigue symptoms preceded diagnosis, whereas others did not notice fatigue symptoms until afterward. Conditions exacerbating fatigue also varied including social situations, stress, and activities requiring concentration as aggravating factors, whereas others cited a lack of engagement or downtime as contributing to worsening symptoms. Interestingly, some participants perceived their PD medications (eg levodopa‐carbidopa) and non‐PD medications (eg primidone) as worsening their fatigue symptoms, whereas others noted no significant change or thought their medications (eg pramipexole and ropinirole) provided additional energy. Last, some participants noted caffeine abated symptoms temporarily, whereas others endorsed no benefit from caffeine.

Theme 4: Complex Relationship with Other Non‐Motor Symptoms

Patients explicitly acknowledged the complex relationship of fatigue to other non‐motor symptoms of PD. Apathy was a common confounding non‐motor symptom. For the initiation of tasks, patients remarked on the difficulty of “separating” perceived fatigue symptoms from apathy, and several noted fatigue worsened apathy by making it harder to mount sufficient energy. Depression was also cited as a confounding non‐motor symptom. One participant endorsed having trouble initiating tasks, ascribing this to either fatigue or depression, but could not pinpoint which symptom contributed most to this behavior because they “are intertwined.” Three others endorsed difficulty separating depression from fatigue, but noted their fatigue was “more debilitating” or “more difficult” than their depressive symptoms. One participant stated that depression and fatigue symptoms were “both physical and mental,” but endorsed the mental component of fatigue being worse than that of depression. Others related their fatigue to sleep issues. Some described situations in which their fatigue caused them to fall sleep at inappropriate times, such as at work or during leisure, and that the quality of their prior night's sleep could impact their fatigue.

Theme 5: Variable Self‐Management Strategies

Participants described a variety of self‐management strategies including exercise, rest, engagement/immersion in fulfilling activities, eating a snack, consuming caffeine, or perseverance through symptoms. Exercise was often cited as having a positive impact on fatigue symptoms, providing participants with “more energy” for a limited time after exercising. Others spoke of sitting and resting, taking naps, getting quality sleep at night, or meditation as strategies to controlling fatigue symptoms. No strategies provided long‐term relief.

Theme 6: General Alignment with Proposed Case Definition Criteria

Participants felt that the proposed case definition aligned with their experience of fatigue, stating “wow, that's my experience!” or “I'm textbook here.” Participants agreed that the description of most symptoms in section A matched their experience, but which symptoms matched their experience varied. A significant number of participants disagreed with criterion A6, expressing that they never avoid doing something because of fear of worsening symptoms. Some participants also disagreed with criterion A7, stating that they seldom or never experience a worsening of symptoms with mild to moderate exertion. Most conversations on these criteria focused on symptoms in section A, with less conversation devoted to sections B, C, or D. However, some participants did comment on section D, suggesting that the ability to differentiate fatigue from other co‐morbidities would be difficult.

Discussion

The themes emerging from this qualitative analysis elucidate the perceptions of fatigue by people living with this symptom and reinforce findings from prior studies regarding the impact of fatigue on function,², ¹⁶ its variability in timing17, 18, 19 and its association with other non‐motor symptoms.²⁰, ²¹ These interviews also raise new perspectives and issues, such as the heterogeneity in participants' descriptions of fatigue, their complex relationship with other non‐motor symptoms and their use of various strategies to combat fatigue. Although we observed a variety of descriptions of symptoms, triggers, timing, relation to other non‐motor symptoms and alleviating factors, we also observed common themes. This suggests that there may be several distinct fatigue phenotypes, which may differ in etiology and optimal therapy that are currently lumped under the single heading of PD‐related fatigue. An unplanned finding, was patients' desire for others to have an increased understanding and empathy for PD‐related fatigue suggesting a need for educational materials for the public, family, and clinicians. Importantly, these interviews provide general validation of proposed case definition criteria for PD‐related fatigue while suggesting some areas for optimization. Because these criteria were based entirely on expert opinion and literature review, they appropriately also point to a need for additional validation in larger samples to optimize both wording and content.

There are no established treatments for fatigue in PD.²² Exercise, involvement in highly focused activities, and snacks were all perceived to provide temporary improvement in fatigue. Although studies of exercise in PD have been small and inconclusive,²³, ²⁴ studies in multiple sclerosis (MS) fatigue suggest that exercise interventions for PD‐related fatigue, particularly strength training, may be worth pursuing.²⁵ Although not yet studied in PD, positive results of behavioral interventions for MS, such as cognitive behavioral therapy and mindfulness approaches, also suggest that this should be pursued in PD.²⁶, ²⁷ Last, improvement in fatigue with snacks suggests the intriguing potential for there to be a metabolic component.²⁸

Limitations of this study include its relatively small sample size and qualitative nature. As a qualitative study, our goals were to generate hypotheses, elicit descriptions and perspectives from persons living with this disorder, and to assess the general ecological validity of case definition criteria. Future studies are needed to confirm the suggestions raised in this study, quantify the importance of results and proceed to more rigorous clinimetric studies of the case definition criteria. Despite these limitations, we feel that these results provide a starting point for several new directions in measurement and therapeutics for PD‐related fatigue.

Author Roles

(1) Research Project: A. Conception, B. Organization, C. Execution; (2) Data ANALYSIS: A. Design, B. Execution, C. Review and Critique; (3) Manuscript Preparation: A. Writing of the First Draft, B. Review and Critique.

D.D.G.: 1B, 1C, 2B, 2C, 3A, 3B

N.K.B.: 1B, 1C, 2C, 3A, 3B

J.M.B.: 1A, 1C, 2C, 3B

J.J.: 1A, 1B, 2A, 2C, 3B

B.M.K.: 1A, 1B, 1C, 2A, 2B, 2C, 3B

Disclosures

Ethical Compliance Statement

Our study was reviewed and approved by the Colorado Multiple Institutional Review Board (Application 15‐1714). All study participants underwent an informed consenting process before participation: oral informed consent was received for focus group participants; and written informed consent was received for individual qualitative interview participants. We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines.

Funding Sources and Conflict of Interest

This work was supported by the Davis Phinney Foundation Research Grant “Novel ‐ Parkinson Disease” and by a “Spark Grant” from ProjectSpark. The authors declare that there are no conflicts of interest relevant to this work.

Financial Disclosures for the Previous 12 Months

B.M.K. has received research funding from the National Institute of Aging, the National Institute for Nursing Research, and the Patient Centered Outcomes Research Institute; he has received honorarium from the Davis Phinney Foundation, the Parkinson Foundation, the International Parkinson and Movement Disorders Society, and the American Academy of Neurology. J.J. has received research funding from the National Institute of Aging, the National Institute for Nursing Research, and the Patient Centered Outcomes Research Institute. Other authors confirm no relevant disclosures.

Supporting information

Table S1. Core themes with descriptive examples

Appendix. Interview domains and sample questions from individual qualitative interviews and focus group interviews