Exploring Fatigue Sensitivity in terms of Mental Health and Fatigue Severity among a Racially and Ethnically Diverse Sample with Severe Fatigue

Abstract

Background:

Fatigue sensitivity, or the misattribution that fatigue symptoms will lead to negative personal consequences, is one individual difference factor related to adverse behavioral health consequences.

Methods:

The current study investigated whether fatigue sensitivity was related to panic symptoms, depression, as well as fatigue severity among 166 persons of diverse racial/ethnic backgrounds with severe fatigue.

Results:

As hypothesized, fatigue sensitivity was statistically significantly related to greater panic symptoms, general depression, and fatigue severity. These results were evident over the variance explained by age, sex, neuroticism, and somatic symptoms.

Conclusions:

This work is the first to evaluate fatigue sensitivity in terms of behavioral health outcomes among a racial/ethnically diverse sample with severe fatigue.

Fatigue is defined as an overwhelming sense of tiredness, weakness, or languor, that can impact an individual’s ability to perform daily activities [1,2]. Fatigue can be experienced as low mood, cognitive deficits, or uncomfortable physical sensations such as headaches, tension, and muscle aches [3]. There is a clinical distinction between fatigue and fatigue related illnesses, such as Chronic Fatigue Syndrome (CFS), as such illnesses include a cluster of debilitating fatigue symptoms that last at least 6 months and often lead to the inability to meet daily expectations [4]. Approximately 7% to 45% of the adult population in the United States has experienced fatigue lasting two weeks or more with the majority of these individuals (59% to 64%) indicating that their fatigue had no defined cause [5–7]. Although fatigue may serve some adaptive purposes, such as signaling the need for rest and protecting the body from overexertion [1,3], fatigue is also a source of economic burden, costing billions of dollars annually in lost productivity [7]. As such, it is imperative to better understand the experience of fatigue and its comorbidity with other health problems (e.g., mental health).

One individual difference factor that has emerged as relevant to the experience of fatigue is fatigue sensitivity. Fatigue sensitivity reflects an individual’s expectations that the experience of fatigue-related symptoms (e.g., headache, muscle aches, impaired physical and/or cognitive functioning, lack of energy) may lead to negative physical, cognitive, or social consequences [8]. For example, an individual with elevated fatigue sensitivity may fear that their fatigue symptoms (e.g., headache) may mean something is seriously wrong with them [8]. Therefore, fatigue sensitivity could amplify emotional reactions to fatigue symptoms [8,9]. Importantly, past work suggests that fatigue sensitivity is theoretically and empirically distinct from the severity of fatigue symptoms [8,10]. Further, studies focused on a range of clinical (chronic pain) and nonclinical samples (i.e., young adults and adults with severe fatigue) suggest that fatigue sensitivity is related to more severe fatigue and such effects are observed over a host of other factors [e.g., personality, health conditions, sleep problems; 10,11]. Other work has found that fatigue sensitivity is associated with problems that frequently co-occur with fatigue states across several populations (e.g., symptoms of depression, anxiety, panic, social anxiety, and higher rates of substance use) among young adults [8] and adults with chronic pain [11]. Specifically, greater fatigue sensitivity has shown to be related to greater self-reported fatigue, depression, anxiety, and panic symptoms among non-clinical young adult samples as well as adults with severe fatigue [8,10]. Additionally, greater fatigue sensitivity relates to greater opioid and alcohol misuse, as well as greater depression symptoms among adults with chronic pain [11].

Despite the promise of past research, no available work has examined the relationship between fatigue sensitivity and fatigue symptoms or fatigue-induced negative consequences (i.e., poor mental health outcomes) among a racially/ethnically diverse sample of adults with severe fatigue. As such, the aim of the current study was to explore the relation between fatigue sensitivity and co-occurring mental health symptoms as well as overall fatigue severity within an ethnically and racially diverse sample of adults experiencing severe fatigue. It was hypothesized that greater fatigue sensitivity would relate to more severe symptoms of panic, general depression, and fatigue severity; these effects were expected to emerge over and above the variance accounted for by theoretically-relevant covariates of age [12], sex [13], neuroticism [14], and somatic symptoms [15]. Specifically, past research suggests that being older, being female, elevated neuroticism, and greater somatic symptoms (e.g., pain) are associated with greater levels of fatigue severity and poorer mental health [e.g., depression and anxiety related symptoms; 8,10,11,16–18]. Therefore, these variables were conceptually useful as covariates to ensure the distinct impact of fatigue on these variables.

Method

Participants

The present sample is a subset of participants from a larger study of mental and physical health at a large, southwestern university. Adults experiencing clinically significant fatigue (N = 166; M_age = 21.35 years; SD_age = 3.50; age range: 18-45 years; 88.0% female) were selected for inclusion. Specifically, inclusion criteria for the current study included experiencing severe fatigue [a score of 5 or higher on the Fatigue Severity Scale; 19,20], being between 18 and 64 years of age, and proficiency in English (to ensure comprehension of study questions).

Approximately 40.4% of the sample identified their ethnicity as Hispanic/Latinx. In addition, 39.8% of the sample identified as Asian, 9.6% identified as Black/African American, 4.2% identified their as White, 3.6% identified as multiracial, and 2.4% identified as Native American.

Measures

Demographic Questionnaire.

A demographic questionnaire was used to collect sociodemographic information. In the current study, age and sex (0 = male, 1 = female) were included as covariates.

Big Five Inventory-10 (BFI-10).

The BFI-10 [21] is a 10-item self-report measure that assesses five key dimensions of an individual’s personality (i.e., extraversion, agreeableness, conscientiousness, neuroticism, and openness to experiences). Each item is scored on a five-point Likert-type scale ranging from 1 (disagree strongly) to 5 (agree strongly). The BFI-10 has demonstrated strong psychometric properties in prior work [21]. In the current study, the two-item neuroticism subscale was averaged and used as a covariate (α = .54).

Patient Health Questionnaire-15 (PHQ-15).

The PHQ-15 [22] is a 15-item self-report measure that indexes somatic symptom severity [23]. The PHQ-15 is comprised of somatic symptoms (e.g., stomach pain) with each item scored on a scale ranging from 0 (not bothered at all) to 2 (bothered a lot). PHQ-15 scores of 5, 10, 15, respectively represent cutoff points for low, medium, and high somatic symptom severity [22]. In the present study, the PHQ-15 demonstrated good internal consistency (α = .80) and was used as a covariate.

Fatigue Sensitivity Questionnaire.

The Fatigue Sensitivity Questionnaire [FSQ; 8] is a 10-item self-report measure that assesses the tendency for individuals to interpret fatigue-related symptoms and sensations as having harmful physical, social, and/or cognitive consequences (e.g., “When I yawn in the presence of others, I fear what people might think of me”). Each item is assessed on a four-point Likert scale ranging from 0 (Very Little) to 3 (Much/Very Much). The total score was created by summing all items and was used as a predictor variable in the current study and demonstrated good internal consistency (α = .87), consistent with past work [8].

Inventory of Depression and Anxiety Symptoms (IDAS).

The IDAS [24] is a 64-item self-report measure that assesses distinct affective symptom clusters. The IDAS consists of 10 specific subscales for suicidality, lassitude, ill temper, well-being, insomnia, appetite loss, appetite gain, panic, social anxiety, and traumatic intrusions, and two broad subscales of general depression and dysphoria. Respondents rate the degree to which they experience symptoms within the past two weeks on a five-point Likert-type scale ranging from 1 (not at all) to 5 (extremely). In the current study, the eight-item panic symptoms (e.g., “I felt like I was choking”) and 20-item general depression (e.g., “I had little interest in my usual hobbies or activities”) subscales were used as criterion variables. Further, cut-off scores of 17, 23, and 31 are indicative of mild, moderate, and severe panic symptoms, respectively. In addition, cut-off scores of 53, 74, and 85 respectively suggest mild, moderate, and severe general depression. The IDAS subscales show strong psychometric properties with both community and psychiatric patient samples [24,25]. In the present work, the two subscales demonstrated excellent internal consistency (panic symptoms α = .90; general depression α = .90).

Fatigue Severity Scale (FSS).

The FSS [26] is a well-validated, nine-item measure of fatigue severity (e.g., “I am easily fatigued”) and interference on activities and lifestyle (e.g., “Fatigue interferes with my work, family, or social life”). Items are rated on a seven-point Likert scale, ranging from 1 (no impairment) to 7 (severe impairment). Scores of five or higher indicate severe levels of fatigue [20]. For the current study, only individuals who endorsed severe fatigue were included in the analyses, and the FSS was used as a criterion variable. The FSS demonstrated excellent internal consistency (α = .92), consistent with past work [26,27].

Procedure

Individuals who met the eligibility criteria completed a battery of self-report measures via Qualtrics, a secure online survey manager system. Participants provided informed consent online before proceeding to the online self-report survey. After completing the Qualtrics survey, participants received extra credit towards their psychology course as compensation. This study protocol was approved by the affiliated university’s Institutional Review Board.

Analytic Strategy

Analyses were conducted using SPSS version 28. Sample descriptive statistics and bivariate correlations among study variables were examined. To evaluate the predictive power of fatigue sensitivity on each criterion variable (i.e., panic symptoms, general depression, fatigue severity), three independent, two-step linear regressions were conducted. For all analyses, step 1 covariates included age [12], sex [13], neuroticism [14], and somatic symptoms [15]. Step 2 included fatigue sensitivity. Model fit for each of the steps was evaluated with the F statistic and an increase in variance accounted for as evidenced by a change in R². Change in R² and squared semi-partial correlations (sr²) were used as indices of effect size [interpreted as .01 = small, .09 = moderate, and .25 = large; 28]. To reduce the likelihood of a Type I error, a Bonferroni correction was applied (.05/3). Thus, only p-values less than .017 were interpreted as being statistically significant.

Results

Bivariate Statistics

Bivariate correlations and descriptive statistics are presented in Table 1. Overall, fatigue sensitivity demonstrated a statistically significant correlation with neuroticism and a greater number of somatic symptoms. Fatigue sensitivity had a positive and statistically significant correlation with panic symptoms, general depression, and fatigue severity symptoms.

Table 1.

Bivariate Correlations and Descriptive Statistics.

Variable	1	2	3	4	5	6	7	8
1. Age a	-
2. Sex (female) a	−.08	-
3. Neuroticism a	−.07	.17*	-
4. Somatic Symptoms a	.06	.22**	.18*	-
5. Fatigue Sensitivity b	−.07	.19*	.28***	.48***	-
6. Panic Symptoms c	−.04	.12	.25**	.54***	.46***	-
7. General Depression c	−.05	.12	.46***	.41***	.52***	.59***	-
8. Fatigue Severity c	.03	.09	.12	.29***	.38***	.32***	.31***	-
Mean/n	21.35	166	7.83	13.28	13.48	16.72	62.97	5.67
SD/%	3.50	88%	1.90	5.43	7.30	7.87	14.62	0.50

Note. N =166.

^*p <.05;

^**p < .01;

^***p < .001.

^acovariate;

^bpredictor variable;

^ccriterion variable. Neuroticism = Big Five Inventory-10 Neuroticism subscale [21]; Somatic Symptoms = Patient Health Questionnaire-15 [22]; Fatigue Sensitivity= Fatigue Sensitivity Questionnaire [8]; Panic Symptoms = Inventory of Depression and Anxiety Symptoms-Panic Symptoms subscale [24]; General Depression = Inventory of Depression and Anxiety Symptoms-General Depression subscale [24]; Fatigue Severity = Fatigue Severity Scale [26].

Regression Analyses

Regression results are presented in Table 2. For panic symptoms, step one of the model with covariates was statistically significant (R² = .32, F(4, 165) = 19.24, p <.001) with somatic symptoms emerging as a significant predictor. In step two, the model with fatigue sensitivity was statistically significant (ΔR² = .04, F(5, 165) = 18.01, p < .001).

Table 2.

Hierarchical Linear Regression Results

Panic Symptoms
Step		b	SE	t	p	CI (l)	CI (u)	sr2
1	Age	−0.15	0.15	−0.99	.323	−0.44	0.15	.004
	Sex	−0.70	1.62	−0.43	.669	−3.90	2.51	.001
	Neuroticism	0.63	0.28	2.28	.024	0.08	1.17	.022
	Somatic Symptoms	0.76	0.10	7.82	< .001*	0.57	0.96	.257
2	Fatigue Sensitivity	0.24	0.08	3.03	.003*	0.09	0.40	.037
General Depression
Step		b	SE	t	p	CI (l)	CI (u)	sr2
1	Age	−0.17	0.27	−0.61	.545	−0.71	0.37	.002
	Sex	−1.33	3.02	−0.44	.661	−7.28	4.63	.001
	Neuroticism	3.05	0.51	5.95	< .001*	2.04	4.06	.149
	Somatic Symptoms	0.94	0.18	5.19	< .001*	0.58	1.30	.113
2	Fatigue Sensitivity	0.69	0.14	4.78	< .001*	0.40	0.97	.085
Fatigue Severity
Step		b	SE	t	p	CI (l)	CI (u)	sr2
1	Age	−0.003	0.01	0.244	.815	−0.02	0.02	< .001
	Sex	0.04	0.12	0.30	.763	−0.20	0.27	.001
	Neuroticism	0.02	0.02	0.94	.347	−0.02	0.06	.005
	Somatic Symptoms	0.03	0.01	3.43	< .001*	0.01	0.04	.067
2	Fatigue Sensitivity	0.02	0.01	3.70	< .001*	0.01	0.03	.072

Note. N for analyses is 166 cases.

^*Significant after Bonferroni correction (alpha = .05/3 = .017);

^**= p <.001. Neuroticism = Big Five Inventory-10 Neuroticism subscale [21]; Somatic Symptoms = Patient Health Questionnaire-15 [22]; Fatigue Sensitivity= Fatigue Sensitivity Questionnaire [8]; Panic Symptoms= Inventory of Depression and Anxiety Symptoms-Panic Symptoms subscale [24]; General Depression = Inventory of Depression and Anxiety Symptoms-General Depression subscale [24]; Fatigue Severity = Fatigue Severity Scale [26].

In terms of general depression, step one with covariates was statistically significant (R² = .32, F(4, 165) = 19.22, p < .001) with neuroticism and somatic symptoms emerging as significant predictors. In step two, fatigue sensitivity was a statistically significant predictor (ΔR² = .09, F(5, 165) = 22.04, p < .001).

In regard to fatigue severity, the overall model with covariates was statistically significant (R² = .09, F(4, 165) = 3.93, p = .005) with somatic symptoms emerging as a significant predictor. Fatigue sensitivity was a statistically significant predictor at step two (ΔR² = .07, F(5, 165) = 6.12, p < .001).

Discussion

The purpose of the current study was to explore the relation between fatigue sensitivity and concurrent mental health and fatigue severity symptoms among an ethnically and racially diverse sample of adults experiencing severe fatigue. Results were consistent with current theory and extant literature. Specifically, fatigue sensitivity was significantly related to greater panic symptoms, general depression, and fatigue severity. The size of the incremental effects for fatigue sensitivity were relatively small, ranging from 4% of variance (for anxious arousal) to 7-8% of variance (for fatigue severity and general depression). However, these findings are particularly noteworthy considering the observed fatigue sensitivity effects were evident in a sample experiencing severe fatigue, over and above the variance explained by a such a comprehensive set of covariates.

There is utility in theorizing how fatigue sensitivity may be related to an exacerbation of such a wide range of behavioral health factors among the studied population. One possibility is that fatigue sensitivity may increase the probability of catastrophic thinking about the negative personal consequences of internal fatigue-related perturbation regardless of the source. That is, the way in which fatigue-related sensations relate to mood states or the way in which psychosomatic symptoms are interpreted may function in distinct ways. Specifically, when such internal symptoms are perceived as non-threatening, persons are less likely to experience intense bodily or negative mood symptoms. In contrast, when such perturbation is perceived as threatening, there is more opportunity for catastrophic thinking [29], fueling dysregulated internal states. For example, a person that is high (versus low) in fatigue sensitivity may likely fear that their fatigue related symptoms such as headaches are indicative of greater physical illness (thereby growing increasingly anxious), or they may internalize these ailments as something “wrong” with them (thereby increasing negative mood states). The internal process of recognizing and misinterpreting fatigue symptoms (i.e., fatigue sensitivity) then may interact with an individual’s learned ability to regulate emotional distress. Such catastrophic thinking may further fuel fatigue sensitivity in a manner of a positive feedback loop. Thus, future work would benefit from employing a longitudinal design in order to address the temporal nature of the studied variables, as the current results cannot support the directional nature of the proposed model. In addition, future research may benefit from exploring mediational processes in the fatigue sensitivity-mental/somatic health relations, including emotional dysregulation [30].

Although not a primary study aim, it is important to note that somatic symptoms emerged as a significant predictor of each criterion variable, highlighting the importance of physical symptoms in terms of behavioral health. This finding highlights the importance of physical symptoms in efforts to better understand mental health and chronic illness among racial and ethnic diverse populations (e.g., depression, anxiety; [31]). In addition, fatigue severity and fatigue sensitivity shared only 14% of variance in the current study. This suggests that these constructs are related, albeit distinct, constructs.

Clinically, the present findings suggest that fatigue sensitivity may be a viable candidate for screening and perhaps intervention programming for persons with severe fatigue. For individuals with elevated fatigue sensitivity, it may be useful to target fatigue sensitivity via cognitive-behavioral methods or graded exercise therapy. Cognitive-behavioral tactics could include psychoeducation about belief symptoms for fatigue (e.g., maladaptive expectancies), distinguishing fatigue beliefs from fatigue symptoms, cognitive re-structuring for fatigue sensitivity, and behavioral practice (e.g., exposure to fatigue symptoms). Past work has shown promise for cognitive behavioral therapy and graded exercise therapy in reducing fatigue symptoms among individuals with CFS [32–36]. It is plausible that refining such treatments to include a fatigue sensitivity reduction element would augment the effects of current evidenced-based psychosocial treatments for severe fatigue, as has been evident for other behavioral health problems [37]. However, future work may benefit from first further identifying for whom the observed relations are evident among, thereby informing subpopulations (moderators) knowledge.

There are limitations to the current study that warrant comment. First, the current sample was primarily composed of females. Future work would benefit from testing the observed relations within a sample consisting of a larger percentage of males to determine the generalizability of the current study’s findings. Second, the data used in the current study was cross-sectional. Thus, no temporal associations between variables can be determined. Future work may benefit from employing a longitudinal approach in order establish the directionality of the effects between fatigue sensitivity and panic, depression, and fatigue severity. Third, participants were college students currently enrolled in a psychology course. It is possible that this group may not be representative of all adults with severe fatigue. Fourth, validated self-report instruments were employed which may account for shared method variance. Future work could extend this line of research by utilizing a multimethod assessment protocol. Finally, the current study represented a racially/ethnically diverse group of individuals. However, future work is needed to examine racial/ethnic differences related to the proposed relations among a larger sample balanced by subgroup.

Overall, this investigation uniquely builds upon past work on fatigue sensitivity. Findings suggest that fatigue sensitivity is an important individual difference factor related to greater panic symptoms, depression, and fatigue severity among ethnically/racially diverse adults with severe fatigue.