Prospective association between C-reactive protein and fatigue in the coronary artery risk development in young adults study

Intraoperative transcutaneous electroacupoint stimulation on early postoperative fatigue in patients with Parkinson's disease undergoing deep brain stimulation surgery

Background

In this clinical trial, we evaluated the effects of transcutaneous electroacupoint stimulation (TEAS) on postoperative fatigue (POF) in Parkinson disease (PD) patients undergoing deep brain stimulation (DBS) surgery.

Methods

A total 60 PD patients undergoing DBS surgery were enrolled. They were randomized to receive either electrical stimulation [alternative frequency 2/10 Hz, dense and disperse, intensity adjusted to the maximum tolerated by the participants (6-15 mAmp)] via surface electrodes (TEAS group) or surface electrodes only without electrical stimulation (Con group) at bilateral Zusanli and Sanyinjiao acupuncture points. All participants received their assigned intervention (TEAS or Con) during the 1st stage of surgery [(except during microelectrode recording (MER)] and the entire 2nd stage of surgery. Intraoperative anesthetic requirements were adjusted based on bispectral index (BIS) monitor. POF was assessed by Christensen fatigue scales (ChrFS), along with Quality of Recovery-15 (QoR-15) and mini-mental state examination (MMSE) postoperatively over a 7-day-period. We recorded the usage of rescue analgesics and anti-emetics.

Results

Fifty-nine patients' datasets were included for final analyses. Fewer patients in TEAS experienced severe POF (defined as ChrFS ≥6) at T3 than those in the Con group (TEAS vs. Con: 7 vs. 22, p < 0.001). During the 1st stage of surgery, more patients in Con group required dexmedetomidine infusion (TEAS vs. Con: 2 vs. 6; P < 0.01). Total dosages of propofol and remifanil during the 2nd stage of surgery were TEAS vs. Con: 374.7 ± 61.2 vs 421.5 ± 81.9; p < 0.001 and 572.3 ± 82.0 vs. 662 ± 148.2; P < 0.001, respectively. Postoperative rescue analgesics (TEAS vs. Con: 2 vs. 6; P < 0.001) were used less in the TEAS group. TEAS patients reported better POF, MMSE and QoR15 scores than those in the Con group during most of the assessment period.

Conclusions

Intraoperative TEAS decreased the severity of POF, reduced intraoperative anesthetic requirements and facilitated post-DBS recovery in this group of PD patients.

The relationship between self-perceived fatigue, muscle endurance, and circulating markers of inflammation in participants of the Copenhagen aging and Midlife Biobank (CAMB)

BACKGROUND

Fatigue, low muscle endurance, muscle weakness and low-grade inflammation are strongly related to frailty at higher age. When signs of self-perceived fatigue and low muscle endurance are interrelated with low-grade inflammation at midlife, they might be used as early markers for frailty. This study investigated whether the interrelationships among self-perceived fatigue, muscle endurance and inflammation can be observed at midlife.

METHODS

A total of 965 participants of the Copenhagen Aging and Midlife Biobank (aged 52 ± 4 years, 536 males, 426 females) were assessed for self-perceived fatigue (20-item multidimensional fatigue inventory), muscle endurance (grip work), circulating markers of inflammation (hsCRP, IL-6, IL-10, TNF-alpha and IFN-γ), daily physical activity (PAS-2), body composition (%body fat assessed by bio-impedance) and self-reported health status. Participants were categorised (correcting for age and gender) according to high fatigue and/or low muscle endurance, differences in inflammatory profile between fatigue categories were assessed by ANCOVA (corrected for PAS-2, %body fat and presence of inflammatory conditions).

RESULTS

Overall, muscle endurance, fatigue and inflammatory markers were significantly interrelated. Higher levels of hsCRP (p < 0.001), IL-6 (p < 0.001), IL-10 (p = 0.035) and TNF-alpha (p = 0.028) were observed in participants presenting both low muscle endurance and high fatigue. IFN-γ was highest in those with high fatigue but normal muscle endurance (p = 0.015).

CONCLUSIONS

Middle-aged participants with higher fatigue in combination with low muscle endurance show higher levels of inflammation, independently from physical activity, body fat and inflammatory pathology. The underlying mechanisms should be identified and future studies should also investigate whether these individuals show early signs of reduced physiological reserve capacity, which in later life come to full expression by means of frailty.

Individual Heterogeneity in the Relations Between Sleep, Inflammation, and Somatic Symptoms

OBJECTIVE

Poor sleep is associated with the experience of more somatic symptoms and a proinflammatory state, whereas a proinflammatory state may also result in the experience of more somatic symptoms. However, existing studies ignore individual differences in these associations. We aimed to study relations between sleep, inflammatory markers, and somatic symptoms at a within-individual level.

METHODS

Time series of daily data on sleep, somatic symptoms, and inflammation markers in 10 healthy individuals (age, 19-58 years; three men) for 63 days were analyzed. Bidirectional lagged ( t - 1) and contemporaneous ( t ) relations between sleep duration, inflammatory markers (C-reactive protein, interferon-α, interleukin 1RA), and somatic symptoms were analyzed using 24-hour urine and diary data. Unified structural equation modeling was used to analyze the association between sleep duration, the three inflammatory markers, and the amount of somatic symptoms at the individual level.

RESULTS

Associations were found between sleep and at least one of three inflammatory markers in four individuals, both positive (three associations) and negative (five associations) and contemporaneous (four associations) and lagged (four associations). Sleep was related to somatic symptoms in four individuals, both positive ( n = 2) and negative ( n = 2) and contemporaneous ( n = 3) and lagged ( n = 1). Inflammatory markers were associated with somatic symptoms in three individuals, both positive (three associations) and negative (one association) and contemporaneous (three associations) and lagged (one associations). Two individuals showed no associations between sleep, inflammatory markers, and somatic symptoms.

CONCLUSIONS

We observed a large variability in presence, strength, and direction of associations between sleep, inflammatory markers, and somatic symptoms.

Anti-Inflammatory Effect of Caffeine on Muscle under Lipopolysaccharide-Induced Inflammation

Evidence has shown that caffeine administration reduces pro-inflammatory biomarkers, delaying fatigue and improving endurance performance. This study examined the effects of caffeine administration on the expression of inflammatory-, adenosine receptor- (the targets of caffeine), epigenetic-, and oxidative metabolism-linked genes in the vastus lateralis muscle of mice submitted to lipopolysaccharide (LPS)-induced inflammation. We showed that caffeine pre-treatment before LPS administration reduced the expression of Il1b, Il6, and Tnfa, and increased Il10 and Il13. The negative modulation of the inflammatory response induced by caffeine involved the reduction of inflammasome components, Asc and Casp1, promoting an anti-inflammatory scenario. Caffeine treatment per se promoted the upregulation of adenosinergic receptors, Adora1 and Adora2A, an effect that was counterbalanced by LPS. Moreover, there was observed a marked Adora2A promoter hypermethylation, which could represent a compensatory response towards the increased Adora2A expression. Though caffeine administration did not alter DNA methylation patterns, the expression of DNA demethylating enzymes, Tet1 and Tet2, was increased in mice receiving Caffeine+LPS, when compared with the basal condition. Finally, caffeine administration attenuated the LPS-induced catabolic state, by rescuing basal levels of Ampk expression. Altogether, the anti-inflammatory effects of caffeine in the muscle can be mediated by modifications on the epigenetic landscape.

Cross-sectional and prospective association between internet addiction and risk of fatigue among Chinese college students

Severe internet addiction (IA) is associated with a higher risk of musculoskeletal pain, but whether there is a significant prospective association between IA and fatigue is unclear. This study aimed to examine the association between IA and fatigue level among Chinese college students. A cross-sectional (n = 1011) and prospective study (n = 653) was conducted to examine the association between IA and risk of fatigue. IA was measured using Young internet addiction test. Fatigue level was evaluated using the Chalder fatigue scale. Multivariate logistic regression analyses showed a cross-sectional association between IA and the risk of fatigue. The odds ratios (95% CIs) of fatigue for normal, mild, and moderate to severe groups were 1.00 (reference), 1.88 (1.20, 2.95), and 5.60 (3.33, 9.42), respectively (P for trend: <0.001). Similarly, multivariate logistic regression analyses also revealed a significant prospective relationship between IA and the risk of fatigue during the 1-year follow-up period. The odds ratios (95% CIs) of fatigue for normal, mild, and moderate to severe groups were 1.00 (reference), 1.56 (0.67, 3.67), and 3.29 (1.08, 10.04), respectively (P for trend: 0.046). Our findings indicate that IA is positively related to risk of fatigue among Chinese college students. Further interventional studies are needed to explore the causality underlying the effects of IA on fatigue.

The Link Between Energy-Related Sensations and Metabolism: Implications for Treating Fatigue

Energy-related sensations include sensation of energy and fatigue as well as subjective energizability and fatigability. First, we introduce interdisciplinary useful definitions of all constructs and review findings regarding the question of whether sensations of fatigue and energy are two separate constructs or two ends of a single dimension. Second, we describe different components of the bodily energy metabolism system (e.g., mitochondria; autonomic nervous system). Third, we review the link between sensation of fatigue and different components of energy metabolism. Finally, we present an overview of different treatments shown to affect both energy-related sensations and metabolism before outlining future research perspectives.

Association of fatigue, inflammation, and physical activity on gait speed: the Long Life Family Study

BACKGROUND

Fatigue, inflammation, and physical activity (PA) are all independently associated with gait speed, but their directionality is not fully elucidated.

AIMS

Evaluate the bidirectional associations amongst fatigue, inflammation, and PA on gait speed.

METHODS

This cross sectional study included probands (n = 1280, aged 49-105) and offspring (n = 2772, aged 24-88) in the Long Life Family Study. We assessed gait speed, fatigue with the question "I could not get going", inflammation using fasting interleukin-6 (IL-6) and high sensitivity C-reactive protein (CRP), and self-reported PA as walking frequency in the past two weeks. The two generations were examined separately using linear mixed modeling.

RESULTS

Lower fatigue, lower IL-6, and greater PA were all associated with faster gait speed in both generations (all p < 0.05); lower CRP was only associated with faster gait speed in the offspring. PA explained the association of fatigue and gait speed via a 16.1% (95% CI 9.7%, 26.7%) attenuation of the direct associations for the probands and 9.9% (95% CI 6.3%, 18.8%) in the offspring. In addition, IL-6 explained more of the association of fatigue and gait speed than the association between PA and gait speed, via a 14.9% (95% CI 9.2%, 23.4%) attenuation of the direct association in the offspring only.

DISCUSSION

Results revealed a potential directionality from fatigue to IL-6 to PA that may lead to faster gait speed. Future work should examine these relationships longitudinally to establish temporality and causality.

CONCLUSIONS

Our findings support a signal that lowering fatigue and inflammation and increasing physical activity may delay functional decline.

Long-Term Fatigue and Cognitive Disorders in Breast Cancer Survivors

Survivors of early-stage breast cancer may report treatment-related side effects that persist for several years after the end of primary treatment. Among these, fatigue and cognitive disorders are frequent complaints and can negatively impact quality of life. Cancer-related fatigue is a very prevalent and distressing long-term side effect among breast cancer survivors that typically improves after completion of treatment, although many patients report severe fatigue several years post-treatment. Cognitive disorders are also common among survivors of breast cancer, especially if treated with chemotherapy. These symptoms are usually mild-to-moderate and often transient. Cognitive recovery is frequently observed within months or a few years after completion of chemotherapy or endocrine therapy. However, some breast cancer survivors may have persistent cognitive difficulties. Several types of interventions have proved to be beneficial in reducing cancer-related fatigue and cognitive difficulties. Most of these interventions for cancer-related fatigue are thought to be effective by reducing inflammation or disrupting pro-inflammatory circuits. Further studies are needed on cognitive management that has showed promising results. This narrative review summarizes the state of the art regarding long-term fatigue and cognitive disorders in patients with early breast cancer, describing prevalence, impact, pathophysiology, and risk factors, and focusing on available interventions.

Predictors of chronic fatigue in adolescents six months after acute Epstein-Barr virus infection: A prospective cohort study

INTRODUCTION

Acute Epstein-Barr virus (EBV) infection is a trigger of chronic fatigue and Chronic Fatigue Syndrome (CFS). This study investigated baseline predictors of chronic fatigue six months after an acute EBV infection.

MATERIALS AND METHODS

A total of 200 adolescents (12-20 years old) with acute EBV infection were assessed for 149 possible baseline predictors and followed prospectively. We performed linear regression to assess possible associations between baseline predictors and fatigue (Chalder Fatigue Questionnaire total score) six months after the acute EBV infection. A total of 70 healthy controls were included for cross-sectional reference. This study is part of the CEBA-project (Chronic fatigue following acute Epstein-Barr virus infection in adolescents).

RESULTS

In the final multiple linear regression model, fatigue six months after acute EBV infection was significantly and independently predicted by the following baseline variables (regression coefficient B[95% CI]): Sensory sensitivity (0.8[0.09-1.6]), pain severity (0.2[0.02-0.3]), functional impairment (1000 steps/day) (-0.3[-0.5 to -0.08]), negative emotions (anxiety) (0.4[0.2-0.6]), verbal memory (correct word recognition) (1.7[0.1-3.3]), plasma C-reactive protein (2.8[1.1-4.4] for CRP values >0.86) and plasma Vitamin B₁₂ (-0.005[-0.01 to -0.001]).

CONCLUSIONS

Development of fatigue after acute EBV infection is to a larger extent predicted by baseline variables related to symptoms and functions than to baseline variables reflecting infectious and immune processes.

TRIAL REGISTRATION

ClinicalTrials, ID: NCT02335437, https://clinicaltrials.gov/ct2/show/NCT02335437.

Impaired mental health and low-grade inflammation among fatigued bereaved individuals

BACKGROUND

Fatigue is a common symptom in stressed individuals. Bereavement is a major life event that has been associated with impaired mental health. Little research has investigated the prevalence of fatigue and its inflammatory correlates in bereaved individuals.

OBJECTIVES

To assess fatigue prevalence and its relationship with mental health outcomes and markers of inflammation, as indexed by C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) in bereaved individuals.

METHODS

Seventy-eight-bereaved adults were examined for fatigue (SF-36 energy/vitality scale), perceived stress (PSS), depression (CES-D), sleep quality (PSQI), pain (SF-36 pain scale), and general health (SF-36 general), and their serum levels of CRP, IL-6 and TNF-α were measured. Group differences between fatigued versus non-fatigued individuals were estimated using analysis of covariance (ANCOVA), with adjustment for body mass index (BMI).

RESULTS

Fatigued bereaved individuals (33%; SF-36 energy/vitality score 0-45) had significantly higher CRP levels (p < .05) as compared to non-fatigued bereaved individuals and reported higher levels of pain (p < .001), greater stress (p < .001), depression (p < .001), and sleeping problems (p < .001), as well as poorer social functioning (p < .001) and general health (p < .001) than those in the non-fatigued group. No group differences were found for IL-6 and TNF-α.

CONCLUSIONS

Fatigued bereaved individuals showed elevated systemic inflammation as measured by CRP in comparison to non-fatigued bereaved individuals. They were also more likely to report mental health problems that co-occur with fatigue in the context of immune activation. Continued research is needed to help clarify the involvement of inflammatory markers in the development of fatigue in a larger sample of bereaved adults.

Age modification of the relationship between C-reactive protein and fatigue: findings from Understanding Society (UKHLS)

BACKGROUND

Systemic inflammation may play a role in the development of idiopathic fatigue, that is, fatigue not explained by infections or diagnosed chronic illness, but this relationship has never been investigated in community studies including the entire adult age span. We examine the association of the inflammatory marker C-reactive protein (CRP) and fatigue assessed annually in a 3-year outcome period for UK adults aged 16-98.

METHODS

Multilevel models were used to track fatigue 7, 19, and 31 months after CRP measurement, in 10 606 UK individuals. Models accounted for baseline fatigue, demographics, health conditions diagnosed at baseline and during follow-up, adiposity, and psychological distress. Sensitivity analyses considered factors including smoking, sub-clinical disease (blood pressure, anaemia, glycated haemoglobin), medications, ethnicity, and alcohol consumption.

RESULTS

Fatigue and CRP increased with age, and women had higher values than men. CRP was associated with future self-reported fatigue, but only for the oldest participants. Thus, in those aged 61-98 years, high CRP (>3 mg/L) independently predicted greater fatigue 7, 19, and 31 months after CRP measurement [odds ratio for new-onset fatigue after 7 months: 1.88, 95% confidence interval (CI) 1.21-2.92; 19 months: 2.25, CI 1.46-3.49; 31 months: 1.65, CI 1.07-2.54]. No significant longitudinal associations were seen for younger participants.

CONCLUSIONS

Our findings support previously described CRP-fatigue associations in older individuals. However, there are clear age modifications in these associations, which may reflect a contribution of unmeasured sub-clinical disease of limited relevance to younger individuals. Further work is necessary to clarify intervening processes linking CRP and fatigue in older individuals.

Are BMI and inflammatory markers independently associated with physical fatigability in old age?

Background

Obesity and chronic low-grade inflammation have both been implicated in the onset of physical fatigue. However, few studies have investigated the independence of these associations in older community-dwelling populations. We therefore aimed to investigate the associations of body mass index (BMI) and inflammatory markers at age 60–64 with perceived physical fatigability at age 68 and to assess whether any such associations were independent of each other and potential confounding factors. A secondary aim was to investigate whether any association with BMI extended back into earlier adulthood.

Methods

Participants of the MRC National Survey of Health and Development (N = 1580) had BMI and levels of interleukin-6 (IL-6) and C-reactive protein (CRP) measured during clinical assessments at age 60–64. These were related to self-perceived physical fatigability assessed at age 68 using the Pittsburgh Fatigability Scale (PFS) (total score:0 (no physical fatigue)–50 (extreme physical fatigue)).

Resuts

Women had higher mean PFS scores than men (mean (SD): 16.0 (9.1) vs 13.2 (8.9), p < 0.01). In sex-adjusted models, BMI, CRP and IL-6 were each associated with PFS scores. When all three factors were included in the same model, BMI and IL-6 remained associated with PFS scores whereas CRP did not. After adjustment for a range of potential confounders, associations of BMI and IL-6 with PFS scores were still evident; fully adjusted differences in mean PFS score = 3.41 (95% CI: 0.59, 6.24) and 1.65 (0.46, 2.84) for underweight and obese participants when compared with normal weight and, 2.78 (1.65, 3.91) when comparing those with an IL-6 of 2.51–8.49 pg/mL with levels <1.50.

Conclusions

BMI and inflammation may both be suitable targets for intervention to reduce the burden of physical fatigability in later life. Further, interventions that target both obesity and elevated levels of IL-6 are likely to be more effective than those focusing on only one.

Immune-based strategies for mood disorders: facts and challenges

INTRODUCTION

Inflammation seems to play a role in the pathophysiology of mood disorders, including major depressive disorder (MDD) and bipolar disorder (BD). In the last years several studies have shown increased levels of inflammatory and/or immune markers in patients with mood disorders. Accordingly, the immune system has become a target of interest for the development of biomarkers and therapeutics for mood disorders. Areas covered: Here, we review the evidence showing low-grade inflammation in mood disorders and the studies evaluating immune-based strategies for the treatment of these conditions. Expert commentary: Clinical trials with non-steroidal anti-inflammatory drugs, polyunsaturated acids, N-acetylcysteine, anti-cytokines, physical activity and probiotics have provided promising results in terms of antidepressant efficacy in patients with MDD and BD. Regarding stem cells, only studies with animal models have been performed so far with interesting pre-clinical results. Due to the preliminary nature of the results, most of the clinical studies need to be replicated and/or confirmed in larger clinical settings, embracing the highly heterogeneous pathophysiology of mood disorders.

Role of Inflammation in Human Fatigue: Relevance of Multidimensional Assessments and Potential Neuronal Mechanisms

Fatigue is a highly disabling symptom in various medical conditions. While inflammation has been suggested as a potential contributor to the development of fatigue, underlying mechanisms remain poorly understood. In this review, we propose that a better assessment of central fatigue, taking into account its multidimensional features, could help elucidate the role and mechanisms of inflammation in fatigue development. A description of the features of central fatigue is provided, and the current evidence describing the association between inflammation and fatigue in various medical conditions is reviewed. Additionally, the effect of inflammation on specific neuronal processes that may be involved in distinct fatigue dimensions is described. We suggest that the multidimensional aspects of fatigue should be assessed in future studies of inflammation-induced fatigue and that this would benefit the development of effective therapeutic interventions.

Plasma leptin concentration is associated with fatigue severity in patients with cardiovascular risk factors - HSCAA study

Fatigue induced by complex dysfunctions of the central nervous system is frequently complained by patients with cardiovascular risk factors. Although leptin is considered to regulate the central nervous system, there are no reports regarding its association with fatigue in those patients. This cross-sectional study included 347 patients with cardiovascular risk factors. Fatigue score and plasma leptin concentration were measured. In addition, abdominal fat accumulation, systemic inflammation, sleep condition, and functions of hypothalamus-pituitary axis and autonomic system were estimated. Plasma leptin concentration (natural logarithm transformed) was significantly and positively (r=0.222, p<0.001) associated with fatigue score, and significantly (p<0.001) higher in the moderately-fatigued group (2.32±0.75ng/ml, mean±SD, n=52) than in the normally-fatigued group (1.85±1.02ng/ml, mean±SD, n=295). Multiple logistic regression analysis showed that plasma leptin concentration was significantly and independently associated with a moderately-fatigued condition independent of other factors, including age, gender, presence of diabetes, hypertension, dyslipidemia, alcohol consumption habit, urinary free cortisol, serum high-sensitive CRP concentration, visceral and subcutaneous fat area, apnea/hypopnea index, sleep efficiency, and heart rate variability. Hyperleptinemia may contribute to fatigue severity in patients with cardiovascular risk factors.

Sleep disturbance and longitudinal risk of inflammation: Moderating influences of social integration and social isolation in the Coronary Artery Risk Development in Young Adults (CARDIA) study

Both sleep disturbance and social isolation increase the risk for morbidity and mortality. Systemic inflammation is suspected as a potential mechanism of these associations. However, the complex relationships between sleep disturbance, social isolation, and inflammation have not been examined in a population-based longitudinal study. This study examined the longitudinal association between sleep disturbance and systemic inflammation, and the moderating effects of social isolation on this association. The CARDIA study is a population-based longitudinal study conducted in four US cities. Sleep disturbance - i.e., insomnia complaints and short sleep duration - was assessed in 2962 African-American and White adults at baseline (2000-2001, ages 33-45years). Circulating C-reactive protein (CRP) was measured at baseline and follow-up (2005-2006). Interleukin-6 (IL-6) and subjective and objective social isolation (i.e., feelings of social isolation and social network size) were measured at follow-up. Sleep disturbance was a significant predictor of inflammation five years later after full adjustment for covariates (adjusted betas: 0.048, P=0.012 for CRP; 0.047, P=0.017 for IL-6). Further adjustment for baseline CRP revealed that sleep disturbance also impacted the longitudinal change in CRP levels over five years (adjusted beta: 0.044, P=0.013). Subjective social isolation was a significant moderator of this association between sleep disturbance and CRP (adjusted beta 0.131, P=0.002). Sleep disturbance was associated with heightened systemic inflammation in a general population over a five-year follow-up, and this association was significantly stronger in those who reported feelings of social isolation. Clinical interventions targeting sleep disturbances may be a potential avenue for reducing inflammation, particularly in individuals who feel socially isolated.

Source-specific social support and circulating inflammatory markers among white-collar employees

BACKGROUND

Despite known beneficial effects of social support on cardiovascular health, the pathway through which sources of support (supervisor, coworkers, family/friends) influence inflammatory markers is not completely understood.

PURPOSE

We investigated the independent and moderating associations between social support and inflammatory markers.

METHODS

A total of 137 male white-collar employees underwent a blood draw for measurement of high-sensitive C-reactive protein (hs-CRP), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF-α), monocyte and leukocyte counts, and completed a questionnaire on social support.

RESULTS

Multivariable linear regression analyses controlling for covariates revealed that supervisor support was inversely associated with IL-6 (β = -0.24, p < 0.01) while coworker support was marginally associated with TNF-α (β = -0.16, p < 0.10). Support from family/friends was not associated with inflammatory markers.

CONCLUSION

Social support from the immediate supervisor may be a potential mechanism through which social support exerts beneficial effects on inflammatory markers in working men.

Cancer-related fatigue--mechanisms, risk factors, and treatments

Fatigue is one of the most common adverse effects of cancer that might persist for years after treatment completion in otherwise healthy survivors. Cancer-related fatigue causes disruption in all aspects of quality of life and might be a risk factor of reduced survival. The prevalence and course of fatigue in patients with cancer have been well characterized and there is growing understanding of the underlying biological mechanisms. Inflammation seems to have a key role in fatigue before, during, and after cancer-treatment. However, there is a considerable variability in the presentation of cancer-related fatigue, much of which is not explained by disease-related or treatment-related characteristics, suggesting that host factors might be important in the development and persistence of this symptom. Indeed, longitudinal studies have identified genetic, biological, psychosocial, and behavioural risk factors associated with cancer-related fatigue. Although no current gold-standard treatment for fatigue is available, a variety of intervention approaches have shown beneficial effects in randomized controlled trials, including physical activity, psychosocial, mind-body, and pharmacological treatments. This Review describes the mechanisms, risk factors, and possible interventions for cancer-related fatigue, focusing on recent longitudinal studies and randomized trials that have targeted fatigued patients.

Association of subsyndromal and depressive symptoms with inflammatory markers among different ethnic groups: the multi-ethnic study of atherosclerosis (MESA)

OBJECTIVE

Depressive symptoms are associated with inflammation yet the association between inflammation and different levels of depression remains unclear. Therefore, we studied the association of subsyndromal and depressive symptoms with inflammatory markers in a large multi-ethnic cohort.

METHODS

C-reactive protein (CRP) (n=6269), interleukin-6 (IL-6) (n=6135) and tumor necrosis factor-alpha (TNF-α) (n=1830) were measured in selected participants from the multi-ethnic study of atherosclerosis (MESA). Subsyndromal depressive symptoms were defined as a CES-D value from 8 to 15, depressive symptoms as a CES-D≥16 and normal as a CES-D≤7. Depressive states (subsyndromal and depressed) were entered into multivariable linear regression models incrementally adjusting for demographic, behavioral, biologic and comorbidities.

RESULTS

Among 6289 participants not taking antidepressants and free from CVD, the mean age was 62.2, while 52% were women, 36.4% were Caucasian, 28.9% African-American, 22.3% Hispanics and 12.4% Chinese-American. Of the total, 24.2% had subsyndromal depression and 11.8% had depressive symptoms. Compared to the non-depressed group and after controlling for demographics, there was no association between both subsyndromal and depressive symptoms with logCRP (β=-0.01, p=0.80 and β=-0.05, p=0.25 respectively), logIL-6 (β=0.01, p=0.71 and β=-0.04, p=0.07 respectively) and logTNF-α (β=-0.03, p=0.29 and β=0.06, p=0.18 respectively). Moreover, fully adjusted models showed no significant associations for logIL-6 and logTNF-α and the different depressive categories. However, with full adjustment, we found a significant inverse association between depressive symptoms and lnCRP (β=-0.10, p=0.01) that was not present for subsyndromal depression (β=-0.05, p=0.11).

CONCLUSION

Among participants not taking anti-depressants, subsyndromal depression is not associated with inflammation. However, depressive symptoms measured by CES-D≥16 are associated with a lower inflammation (CRP).

Association of psychological stress response of fatigue with white blood cell count in male daytime workers

Relationships between work-related psychological and physical stress responses and counts of white blood cells (WBCs), neutrophils, and lymphocytes were investigated in 101 daytime workers. Counts of WBCs and neutrophils were positively associated with smoking and inversely correlated with high density lipoprotein (HDL)-cholesterol levels. Additionally, general fatigue score as measured by the profile of mood state was positively correlated with WBC and neutrophil counts whereas lymphocyte counts was not significantly associated with fatigue score. Multiple regression analysis showed that WBC count was significantly related to general fatigue, age, and HDL-cholesterol levels. Neutrophil count was significantly related to HDL-cholesterol levels and fatigue score. Among various psychological stress response variables, general fatigue may be a key determinant of low-grade inflammation as represented by increases of WBC and neutrophil counts.

Peripheral cytokines as a chemical mediator for postconcussion like sickness behaviour in trauma and perioperative patients: literature review

Besides brain injury and systemic infection, cognitive and concussion like sickness behaviour is associated with muscular trauma and perioperative patients, which represents a major obstacle to daily activities and rehabilitation. The neuroinflammatory response triggers glial activation and consequently the release of proinflammatory cytokines within the hippocampus. We review clinical studies that have investigated neurocognitive and psychosomatic symptoms related to muscular trauma and in perioperative conditions. These include impaired attention and executive and general cognitive functioning. The purpose of this literature review is to focus on the systemic inflammation and the role of proinflammatory cytokines IL1, IL6,and TNF and other inflammatory mediators which mediates the cognitive impairment and induces sickness behaviour. Moreover, this review will also help to determine if some patients could have long-term cognitive changes associated with musculoskeletal injuries or as a consequence of surgery and thereby will lead to efforts in reducing that risk.

Chronic low-grade inflammation in metabolic disorders: relevance for behavioral symptoms

The ability of cytokines to influence cerebral functions and to induce the development of behavioral alterations is well established in conditions of acute or chronic high-grade activation of the innate immune system. Recent evidence suggests that the release of these immune mediators during chronic low-grade endogenous inflammatory processes may also contribute to the development of behavioral alterations. Metabolic disorders, including obesity, type 2 diabetes and the metabolic syndrome, represent examples of those conditions which are both characterized by a chronic low-grade inflammatory state and an increased prevalence of behavioral disorders. In metabolic disorders, the increased production of acute-phase proteins and cytokines (e.g. C-reactive protein, interleukin-6 and tumor necrosis factor-α), but at relatively low levels, may promote and contribute to the development of behavioral symptoms, including depressive symptoms, cognitive impairment, fatigue, sleep problems and pain. This hypothesis is supported by a growing literature referring both to experimental and clinical findings that will be reviewed here.

Association of C-reactive protein and interleukin-6 with new-onset fatigue in the Whitehall II prospective cohort study

BACKGROUND

Although basic research on neuroimmune interactions suggests that inflammatory processes may play a role in the development of fatigue, population-based evidence on this association is limited. This study examined whether plasma C-reactive protein (CRP) and interleukin-6 (IL-6), biomarkers of systemic inflammation, predict fatigue onset.

METHOD

The Whitehall II study is a large-scale cohort study conducted in 20 civil service departments in London. Plasma CRP and IL-6 were measured in 4847 non-fatigued participants at phase 3 (1991-1993, aged 39-63 years). Fatigue was assessed using the Vitality subscale of the 36-item Short Form Health Survey (SF-36) at phase 3 and phase 4 (1995-1996).

RESULTS

During a mean follow-up of 3.1 years, 957 new fatigue cases (19.7%) were identified using the pre-established cut-off score of ≤ 50 on the Vitality subscale. CRP values were dichotomized as low (<1.0 mg/l ) or high (≥ 1.0 mg/l) using the Centers for Disease Control/American Heart Association recommendations. Similarly, IL-6 values were also dichotomized as low (<1.5 pg/ml) or high (≥ 1.5 pg/ml). After full adjustment for sociodemographic and biobehavioral covariates, the odds ratios for new-onset fatigue were 1.28 [95% confidence interval (CI) 1.09-1.49, p = 0.003] for high CRP and 1.24 (95% CI 1.06-1.45, p = 0.008) for high IL-6. Similar results were found when CRP and IL-6 were treated as continuous variables.

CONCLUSIONS

Plasma CRP and IL-6 were prospectively associated with new-onset fatigue, supporting the hypothesis that low-grade inflammation has a role in the development of fatigue.

Fatigue symptoms relate to systemic inflammation in patients with type 2 diabetes

Fatigue is frequent in patients with diabetes and this symptom appears to be more prominent in type 2 rather than type 1 diabetic subjects. Chronic inflammation represents one characteristic of type 2 diabetes that may contribute to fatigue symptoms. This possibility was assessed in a sample of 20 type 2 diabetic patients relatively to a group of 20 type 1 diabetic subjects. Specific dimensions of fatigue, including general fatigue, physical fatigue, reduced activity, mental fatigue and reduced motivation, were assessed using the Multidimensional-Fatigue-Inventory (MFI). Biological assays comprised the measurement of serum inflammatory markers [high-sensitive C-reactive-protein (hsCRP), high-sensitive interleukin-6 (hsIL-6), high-sensitive tumor-necrosis-factor-α (hsTNF-α) and neopterin]. Clinical parameters including indexes of adiposity were collected. In comparison to type 1 diabetic subjects, patients with type 2 diabetes exhibited higher fatigue scores, notably in the dimensions of general fatigue, physical fatigue and reduced activity, together with greater levels of inflammatory markers that correlated with indexes of adiposity. Regression analyses controlling for diabetes duration, insulin treatment status, glycemic control and fasting status, indicated that levels of inflammatory markers, in particular hsIL-6, hsCRP and neopterin, were associated with MFI fatigue dimensions in type 2 diabetic patients. Mediation analyses revealed that adiposity did not significantly account for the relationship of inflammatory markers with fatigue scores albeit coefficient regressions decreased somewhat when this variable was controlled for in regression models. These findings indicate that systemic low-grade inflammation relates to fatigue symptoms in patients with type 2 diabetes and suggest the involvement of inflammatory processes in the pathophysiology of diabetes-related fatigue.

Early life stress and inflammatory mechanisms of fatigue in the Coronary Artery Risk Development in Young Adults (CARDIA) study

Fatigue is highly prevalent and causes serious disruption in quality of life. Although cross-sectional studies suggest childhood adversity is associated with adulthood fatigue, longitudinal evidence of this relationship and its specific biological mechanisms have not been established. This longitudinal study examined the association between early life stress and adulthood fatigue and tested whether this association was mediated by low-grade systemic inflammation as indexed by circulating C-reactive protein (CRP) and interleukin-6 (IL-6). In the Coronary Artery Risk Development in Young Adults (CARDIA) study, a population-based longitudinal study conducted in 4 US cities, early life stress was retrospectively assessed in 2716 African-American and white adults using the Risky Families Questionnaire at Year 15 examination (2000-2001, ages 33-45 years). Fatigue as indexed by a loss of subjective vitality using the Vitality Subscale of the 12-item Short Form Health Survey was assessed at both Years 15 and 20. While CRP was measured at both Years 15 and 20, IL-6 was measured only at Year 20. Early life stress assessed at Year 15 was associated with adulthood fatigue at Year 20 after adjustment for sociodemographic characteristics, body-mass index, medication use, medical comorbidity, smoking, alcohol consumption, physical activity, current stress, pain, sleep disturbance as well as Year 15 fatigue (adjusted beta 0.047, P=0.007). However, neither CRP nor IL-6 was a significant mediator of this association. In summary, early life stress assessed in adulthood was associated with fatigue 5 years later, but this association was not mediated by low-grade systemic inflammation.

The associations of adiposity, physical activity and inflammation with fatigue in older adults

Persistent feelings of fatigue are a widespread complaint reported by older adults, and are associated with detriments in health and quality of life. The aim of this study was to determine the influence of weight status, habitual physical activity and inflammation, after controlling for common psychosocial variables such as depression, on perceptions of fatigue in relatively healthy older adults. Older men and women (N=182, age=69.2±6.7 years, 98 men) were assessed for adiposity via dual-energy X-ray absorptiometry, physical activity (PA) using accelerometers, systemic inflammation [serum C-reactive protein (CRP), interleukin-6 (IL-6), sIL-6R and WBC count], fatigue according to the Multidimensional Fatigue Inventory (MFI), sleep using the Pittsburgh Sleep Quality Index (PSQI) and depression via the Geriatric Depression Scale (GDS). Men and women reported similar levels of fatigue in all dimensions (p>0.05) except women reported higher levels of mental fatigue than men (p=0.049). With the exception of mental fatigue, adiposity was positively, and physical activity was inversely associated with all other dimension of fatigue (r range=0.20-0.42, and -0.18 to -0.37, respectively). CRP, IL-6 and WBC were also related to several dimensions of fatigue (r range=0.15-0.26). Regression analyses revealed that after controlling for other factors, including depression and sleep quality, adiposity independently explained a significant amount of the variance in general and physical fatigue. In addition to depression and sleep quality, adiposity may represent a potential target for reducing fatigue in older adults.

Association of general fatigue with cellular immune indicators among healthy white-collar employees

OBJECTIVE

Although fatigue is a common complaint in the working population, underlying immunological mechanisms are not well understood. This study investigated the association of general fatigue with cellular immune indicators.

METHODS

A total of 148 healthy white-collar employees (70% men) underwent a blood draw for the measurement of natural killer (NK), B, and T cell counts as well as NK cell cytotoxicity (NKCC) and completed two different fatigue scales, that is, Profile of Mood State (POMS) and Maastricht Questionnaire (MQ).

RESULTS

Multiple linear regression analyses revealed that POMS fatigue score was significantly associated with decreases of NK cells (β = -.407) and NKCC (β = -.215), whereas MQ fatigue score was significantly associated with reduced NK cells (β = -.290) but not with NKCC (β = -.127).

CONCLUSION

The results suggest that general fatigue may be related to impaired NK cell competency among healthy employees.

Reciprocal regulation of the neural and innate immune systems

Innate immune responses are regulated by microorganisms and cell death, as well as by a third class of stress signal from the nervous and endocrine systems. The innate immune system also feeds back, through the production of cytokines, to regulate the function of the central nervous system (CNS), and this has effects on behaviour. These signals provide an extrinsic regulatory circuit that links physiological, social and environmental conditions, as perceived by the CNS, with transcriptional 'decision-making' in leukocytes. CNS-mediated regulation of innate immune responses optimizes total organism fitness and provides new opportunities for therapeutic control of chronic infectious, inflammatory and neuropsychiatric diseases.

Fatigue and gene expression in human leukocytes: increased NF-κB and decreased glucocorticoid signaling in breast cancer survivors with persistent fatigue

Fatigue is highly prevalent in the general population and is one of the most common side effects of cancer treatment. There is growing evidence that pro-inflammatory cytokines play a role in cancer-related fatigue, although the molecular mechanisms for chronic inflammation and fatigue have not been determined. The current study utilized genome-wide expression microarrays to identify differences in gene expression and associated alterations in transcriptional activity in leukocytes from breast cancer survivors with persistent fatigue (n=11) and non-fatigued controls (n=10). We focused on transcription of inflammation-related genes, particularly those responsive to the pro-inflammatory NF-κB transcription control pathway. Further, given the role of glucocorticoids as key regulators of inflammatory processes, we examined transcription of glucocorticoid-responsive genes indicative of potential glucocorticoid receptor (GR) desensitization. Plasma levels of cortisol were also assessed. Consistent with hypotheses, results showed increased expression of transcripts with response elements for NF-κB, and reduced expression of transcripts with response elements for glucocorticoids (p<.05) in fatigued breast cancer survivors. No differences in plasma levels of cortisol were observed. These data indicate that increased activity of pro-inflammatory transcription factors may contribute to persistent cancer-related fatigue and provide insight into potential mechanisms for tonic increases in NF-κB activity, specifically decreased expression of GR anti-inflammatory transcription factors.

Sleep depth and fatigue: role of cellular inflammatory activation

Individuals with underlying inflammation present with a high prevalence of non-specific co-morbid symptoms including sleep disturbance and fatigue. However, the association between cellular expression of proinflammatory cytokines, alterations of sleep depth and daytime fatigue has not been concurrently examined. In healthy adults (24-61 years old), evening levels of monocyte intracellular proinflammatory cytokine production were assessed prior to evaluation of polysomnographic sleep and measures of fatigue the following day. Stimulated monocyte production of interleukin-6 (IL-6), but not tumor necrosis factor α (TNF-α), was negatively associated with slow wave sleep (ΔR²=.17, p=.029). In contrast, stimulated monocyte production of IL-6 was positively associated with rapid-eye movement (REM) sleep duration during the first sleep cycle (ΔR²=.26, p<.01). Moreover, evening stimulated production of IL-6 was associated with fatigue the following day (ΔR²=.17, p=.05). Mediation analyses showed that slow wave sleep, but not REM sleep duration, mediated the relationship between evening levels of IL-6 production and daytime fatigue. These results indicate that increases in stimulated monocyte production of IL-6 may be associated with decreases in slow wave sleep and increases in REM sleep duration. Relative loss of slow wave sleep may be one pathway through which cellular inflammation leads to daytime fatigue.

Fatigue in older adults: an early indicator of the aging process?

The aim of this paper is to give an overview of research on fatigue in older adults, with a focus on fatigue as an early indicator of the aging process. Fatigue is a strong predictor of functional limitations, disability, mortality, and other adverse outcomes in young-old and old-old populations, between men and women, and in different geographic localities. Several biological, physiological and social explanations are proposed: fatigue may be seen not only as a self-reported indicator of frailty, defined as a physiologic state of increased vulnerability to stressors, which results from decreased physiologic reserves and even dysregulation of multiple physiologic systems, but also this state may be accelerated because of the cumulative impact of social, mental and biological factors throughout life.