The representation of inflammatory signals in the brain - a model for subjective fatigue in multiple sclerosis

Alterations in functional connectivity of interoceptive and Cortico-Subcortical areas in Multiple Sclerosis-Related fatigue

Fatigue in people with Multiple Sclerosis (PwMS) is a poorly understood, complex, and disabling symptom. We hypothesized that the perception of fatigue in PwMS results from increased information processing in cortical areas responsible for the perception of bodily states and decreased information processing in the cortico-basal ganglia network involved in the perception of motor performance. We investigated whether PwMS who perceive excessive fatigue would have increased resting-state functional connectivity (rsFC) between interoceptive brain areas (amygdala, anterior cingulate cortex [ACC], and insula) and decreased rsFC between cortico-basal ganglia premotor network compared to PwMS not reporting fatigue. Twenty-three relapsing-remitting PwMS were divided into fatigued versus non-fatigued groups based on the Modified Fatigue Impact Scale score (≥38 points). Age-matched healthy controls (n = 21) were also analyzed. All the participants underwent resting-state functional magnetic resonance imaging. PwMS who perceived abnormal fatigue, compared to non-fatigued PwMS, showed reduced rsFC between cortico-basal ganglia network and increased rsFC within interoceptive brain areas (amygdala, ACC, and insula) involved in perception of bodily states (P ≤ 0.01). Increased rsFC within interoceptive brain areas was specific for fatigued PwMS as this result did not appear when comparing PwMS (fatigued and non-fatigued) with healthy controls. The Modified Fatigue Impact Scale scores were correlated with the increased rsFC between interoceptive brain areas (amygdala and insula) and decreased rsFC between cortico-basal ganglia (P < 0.01). MS-related perceived fatigue has a central cause, and it may be due to increased interoceptive brain activity (perception of bodily states). Interventions are needed to decrease fatigue and reorganize the brain circuitry.

Understanding the mechanisms of fatigue in multiple sclerosis: linking interoception, metacognition and white matter dysconnectivity

One of the most prominent symptoms in multiple sclerosis is pathological fatigue, often described by sufferers as one of the most debilitating symptoms, affecting quality of life and employment. However, the mechanisms of both, physical and cognitive fatigue in multiple sclerosis remain elusive. Here, we use behavioural tasks and quantitative MRI to investigate the neural correlates of interoception (the ability to sense internal bodily signals) and metacognition (the ability of the brain to assess its own performance), in modulating cognitive fatigue. Assuming that structural damage caused by multiple sclerosis pathology might impair the neural pathways subtending interoception and/or metacognition, we considered three alternative hypotheses to explain fatigue as a consequence of, respectively: (i) reduced interoceptive accuracy, (ii) reduced interoceptive insight or (iii) reduced global metacognition. We then explored associations between these behavioural measures and white matter microstructure, assessed by diffusion and magnetisation transfer MRI. Seventy-one relapsing-remitting multiple sclerosis patients participated in this cross-sectional study (mean age 43, 62% female). Patient outcomes relevant for fatigue were measured, including disability, disease duration, depression, anxiety, sleepiness, cognitive function, disease modifying treatment and quality of life. Interoceptive and metacognitive parameters were measured using heartbeat tracking and discrimination tasks, and metacognitive visual and memory tasks. MRI was performed in 69 participants, including diffusion tensor MRI, neurite orientation dispersion and density imaging and quantitative magnetisation transfer. Associations between interoception and metacognition and the odds of high cognitive fatigue were tested by unconditional binomial logistic regression. The odds of cognitive fatigue were higher in the people with low interoceptive insight (P = 0.03), while no significant relationships were found between fatigue and other interoceptive or metacognitive parameters, suggesting a specific impairment in interoceptive metacognition, rather than interoception generally, or metacognition generally. Diffusion MRI-derived fractional anisotropy and neurite density index showed significant (P < 0.05) negative associations with cognitive fatigue in a widespread bilateral white matter network. Moreover, there was a significant (P < 0.05) interaction between cognitive fatigue and interoceptive insight, suggesting that the poorer the white matter structure, the lower the interoceptive insight, and the worse the fatigue. The results point towards metacognitive impairment confined to the interoceptive domain, in relapsing-remitting patients with cognitive fatigue. The neural basis of this impairment is supported by a widespread white matter network in which loss of neurite density plays a role.

The multidimensional assessment of body representation and interoception in multiple sclerosis

BACKGROUND

The mental representation of the body (or body representation, BR) derives from the processing of multiple sensory and motor inputs and plays a crucial role in guiding our actions and in how we perceive our body. Fundamental inputs for BR construction come also from the interoceptive systems which refer to the whole bidirectional processes between the brain and the body. People with Multiple sclerosis (MS) show an abnormal multisensory integration which may compromise BR and interoception integrity. However, no study has evaluated possible deficits on distinct and dissociable dimensions of body representation (i.e., action-oriented, aBR; and a nonaction-oriented body representation, NaBR) and interoception (i.e., interoceptive accuracy, interoceptive sensibility, and interoceptive awareness) in MS.

OBJECTIVE

In the present study, we aimed to determine whether participants with MS present changes in BR and interoceptive dimensions.

METHODS

We performed comparison analyses on tasks and questionnaires tapping all BR and interoceptive dimensions between 36 people with relapsing-remitting MS (RRMS) and 42 healthy controls, and between 23 people with progressive MS (PMS) and 33 healthy controls.

RESULTS

Overall, patients with MS exhibited lower interoceptive accuracy than matched controls. The RRMS group also showed higher visceral interoceptive sensibility levels. No differences were found in BR accuracy measures, but the PMS reported longer response times when performing the aBR task.

CONCLUSION

These findings open a new issue on the role of inner-signal monitoring in the body symptomatology of MS and highlight the need for an accurate BR and interoceptive assessment in a clinical setting.

Comments on energy conservation treatments for MS-related fatigue and a new proposal

Psychological treatments of MS-related fatigue mostly depend on energy conservation programs. We argue that the evidence for energy conservation training is weak - in contrast to some reviews on this topic. The reasons for our concerns are the use of informed passive control groups allowing negative placebo effects, the lack of predefined primary outcome parameter, statistically rather than clinically significant effects, and the use of insensitive fatigue questionnaires. We propose to base psychological interventions not on a view of fatigue as a constant loss of mental energy but as a subjective representation ("feeling") of an inflammatory state, which draws away attentional capacity. This conceptualization allows to develop a three-step treatment approach: Getting short-term control on fatigue, extinction to reduce fatigue-related avoidance behavior, and a systematic increase of activities by pacing. Our proposal depends on the techniques, that can interrupt ongoing feelings of fatigue and can serve as a basis for extinction. We propose that Progressive Muscle Relaxation might be such a technique. The advantage of our model is that it shares similarities with well-established treatments for phobias and chronic pain and we discuss the shared set of assumptions. Hopefully, this will help to improve the treatment of fatigue in future.

Structural neural correlates of mental fatigue and reward-induced improvement in performance

Neuroimaging studies investigating the association between mental fatigue (henceforth fatigue) and brain physiology have identified many brain regions that may underly the cognitive changes induced by fatigue. These studies focused on the functional changes and functional connectivity of the brain relating to fatigue. The structural correlates of fatigue, however, have received little attention. To fill this gap, this study explored the associations of fatigue with cortical thickness of frontal and parietal regions. In addition, we aimed to explore the associations between reward-induced improvement in performance and neuroanatomical markers in fatigued individuals. Thirty-nine healthy volunteers performed the psychomotor vigilance task for 15 min (i.e., 3 time-on-task blocks of 5 min) out of scanner; followed by an additional rewarded block of the task lasting 5 min. Baseline high-resolution T1-weigthed MR images were obtained. Reaction time increased with time-on-task but got faster again in the rewarded block. Participants' subjective fatigue increased during task performance. In addition, we found that higher increase in subjective mental fatigue was associated with the cortical thickness of the following areas: bilateral precuneus, right precentral gyrus; right pars triangularis and left superior frontal gyrus. Our results suggest that individual differences in subjective mental fatigue may be explained by differences in the degree of cortical thickness of areas that are associated with motor processes, executive functions, intrinsic alertness and are parts of the default mode network.

Overview of the Current Pathophysiology of Fatigue in Multiple Sclerosis, Its Diagnosis and Treatment Options - Review Article

Fatigue is a common, debilitating and often underestimated symptom in patients with multiple sclerosis (MS). The exact pathophysiological mechanism of fatigue in MS is still unknown. However, there are many theories involving different immunological, metabolic and inflammatory mechanisms of fatigue. Owing to the subjective nature of this symptom, its diagnosis is still very limited and is still based only on diagnostic questionnaires. Although several therapeutic agents have been used in the past to try to influence fatigue in MS patients, no single effective approach for the treatment of fatigue has yet been found. This review article aims to provide the reader with information on the current theories on the origin and mechanism of fatigue in MS, as well as diagnostic procedures and, finally, current therapeutic strategies for the management of fatigue in MS patients.

Comparing two relaxation procedures to ease fatigue in multiple sclerosis: a single-blind randomized controlled trial

BACKGROUND

Various relaxation procedures have been proposed to reduce fatigue in multiple sclerosis (MS). However, it is unknown, which type of relaxation has the largest effect on fatigue reduction and on autonomic nervous system (ANS) activity.

OBJECTIVE

We aimed to compare two biofeedback-supported relaxation exercises: a deep breathing (DB) exercise and progressive muscle relaxation (PMR), which may ameliorate MS fatigue and alter ANS activity.

METHODS

We performed a single-blind randomized clinical trial, introducing MS patients (n = 34) to the DB or PMR exercise. We first tested cardiovagal integrity, reflected by changes in heart rate variability (HRV) in response to DB. Participants then performed a fatigue-inducing vigilance task, followed by the DB or PMR. State fatigue was recorded consecutively at baseline, after the vigilance task, and after the relaxation exercise, along with HRV reflecting ANS activity.

RESULTS

Only patients assigned to the PMR group experienced a significant drop in fatigue, whereas both relaxation exercises changed ANS activity. MS patients showed the expected autonomic response during the cardiovagal reflex test. The vigilance task elevated short-term feelings of fatigue and significantly reduced HRV parameters of parasympathetic activity. Trait fatigue was negatively correlated with HRV during the second half of the vigilance task.

CONCLUSION

PMR alleviates short-term feelings of fatigue in persons with MS. The vigilance task in combination with HRV measurements may be helpful for evaluating relaxation procedures as a treatment of fatigue. Hereby, future studies should ensure longer and more frequent relaxation exercises and focus on patients with weak to moderate fatigue.

TRIAL REGISTRATION

Trial Registry: DRKS00024358.

Autonomic nervous system disorders in multiple sclerosis

Multiple sclerosis (MS) is a chronic progressive demyelinating disease of the central nervous system (CNS), which also affects the autonomic nervous system (ANS). Manifestations of MS in the ANS include urological, sexual, gastrointestinal, cardiovascular, and thermoregulatory disorders as well as increased fatigue. These problems are common yet are often underestimated due to the non-specificity of the symptoms and the limited evaluation of the ANS in the usual clinical practice. Most of these symptoms seem to be related to localized lesions in the CNS. However, the mechanisms by which these disorders are caused in MS have not been fully investigated, thus preventing any focused etiological treatment. The most common disorders of the ANS in MS represent a challenge for clinicians due to the variability of the clinical picture and our minimal data on their diagnosis and treatment. Early diagnosis and initiation of individualized treatment regimens, often in need of multiple approaches, seem to yield the best results in managing ANS dysfunction in MS patients.

Effects of repetitive twice-weekly transcranial direct current stimulations on fatigue and fatigability in people with multiple sclerosis

Fatigue is associated with a dramatically decreased quality of life in people with multiple sclerosis (pwMS). It refers to a constant subjective feeling of exhaustion and performance decline, known as fatigability. However, inconsistency and heterogeneity in defining and assessing fatigue have led to limited advances in understanding and treating MS-associated fatigue. Transcranial direct current stimulation (tDCS) has emerged as a promising, non-pharmaceutical treatment strategy for subjective fatigue. However, whether repetitive tDCS also have long-term effects on time-on-task performance has not yet been investigated. This pseudorandomized, single-blinded, and sham-controlled study investigated tDCS effects on behavioral and electrophysiological parameters. 18 pwMS received eight twice-weekly 30 min stimulations over the left dorsolateral prefrontal cortex. Fatigability was operationalized as time-on-task-related changes in reaction time variability and P300 amplitude. Additionally, subjective trait and state fatigue ratings were assessed. The results revealed an overall decrease in subjective trait fatigue ratings that lasted at least four weeks after the stimulations. However, the ratings declined after both anodal and sham tDCS. No effects were found on subjective state fatigue and objective fatigability parameters. Linear Mixed Models and Bayesian Regression models likewise favored the absence of a tDCS effect on fatigability parameters. The results confirm the complex relationship between MS-associated fatigue and fatigability. Reliable and clinically relevant parameters need to be established to extend the potential of tDCS for treating fatigability. Furthermore, our results indicate that consecutive stimulations rather than twice-weekly stimulations should be the preferred stimulation scheme in future studies.

Volumetric changes in hypothalamic subunits in patients with relapsing remitting multiple sclerosis

PURPOSE

Studies on hypothalamic changes in patients with relapsing remitting multiple sclerosis (RRMS) are very scarce, despite the fact that the relationship with the hypothalamus is frequently reported. The aim of the study was to determine the volume of the hypothalamic subunits and the total hypothalamus and its relationship with the total demyelinating lesion volume (TLV) and expanded disability status scale (EDSS) in RRMS patients.

METHODS

In this cross-sectional study, anterior-superior, superior tubular, posterior hypothalamus, anterior-inferior, inferior tubular subunits of hypothalamus, and total hypothalamus volume were calculated, with fully automatic analysis methods using volumetric T1 images of 65 relapsed RRMS patients and 68 healthy controls (HC). Volume changes in the hypothalamus and its subunits in RRMS patients were examined using multivariate analysis of covariance (MANCOVA). The relationship of these volumes with EDSS and TLV was investigated by partial correlation analysis.

RESULTS

There is volume reduction in total hypothalamus (F = 13.87, p < 0.001), anterior-superior (F = 19.2, p < 0.001), superior tubular (F = 10.1, p = 0.002) subunits, and posterior hypothalamus (F = 19.2, p < 0.001) volume in RRMS patients. EDSS correlates negatively with anterior-superior (p = 0.017, r =  - 0.333), superior tubular subunits (p = 0.023, r =  - 0.439), posterior hypothalamus (p < 0.001, r =  - 0.511), and whole hypothalamus volume (p = 0.001, r =  - 0.439). TLV correlates negatively with anterior superior (p < 0.001, r =  - 0.565), anterior inferior (p = 0.002, r =  - 0.431), superior tubular subunits (p = 0.002, r =  - 0.432), posterior hypothalamus (p < 0.001, r =  - 0.703), and whole hypothalamus (p < 0.001, r =  - 0.627) volumes.

CONCLUSION

This study demonstrates a reduction in total hypothalamus volume, anterior-superior, superior tubular, and posterior hypothalamus in patients with RRMS. Anterior-superior and superior tubular subunit, posterior hypothalamus, and total hypothalamus volume were negatively correlated with TLV and EDSS scores.

Fatigability-related oscillatory brain activity changes in people with MS

BACKGROUND

Fatigue, a multidimensional and challenging symptom associated with various underlying conditions, can manifest as a subjective feeling and a performance fatigability. The latter is often defined as an objectively measurable performance decline with time on task. Both syndromes are highly prevalent in people with multiple sclerosis (pwMS) and are often resistant to medical therapy. In the absence of valid and reliable objective parameters, the current cognitive fatigue diagnosis remains purely subjective. Assessing brain wave activity changes has repeatedly been a viable strategy for monitoring cognitive fatigue in healthy subjects. In this study, we aimed to investigate oscillatory brain activity changes and their associations with subjective fatigue in pwMS.

METHODS

We enrolled 21 pwMS and 21 healthy controls (HC) in this study. Subjects performed a sustained attention task divided into six blocks over the course of 30 minutes, and underwent resting state EEGs before and after the task. During the task, subjects were repeatedly asked to rate their subjective levels of mental fitness, mental exhaustion, and mind wandering. Using Linear Mixed Models, we explored fatigability-related changes by focusing on the time course of changes in reaction time variability, subjective ratings of fatigability, as well as frontomedial theta, and occipital alpha power. We further investigated initial and fatigability-induced differences between pwMS and HC at rest. Finally, Pearson correlations were used to examine the relationship between subjective fatigue and objective fatigability parameters.

RESULTS

Our results revealed a systematically stronger fatigability development in pwMS that was objectively measurable. PwMS reported lower mental fitness levels and demonstrated greater variability in reaction times with time on task. Occipital alpha power significantly increased during the task. Especially for upper alpha power, this increase was significantly more prominent in pwMS compared to HC. However, the time-on-task-induced changes in our study were not associated with the subjective fatigue ratings.

CONCLUSIONS

The results of this study expand the understanding of the neural mechanisms underlining cognitive fatigability and may complement the fatigue diagnosis and therapy monitoring with quantitative objective methods.

Heart rate variability and fatigue in MS: two parallel pathways representing disseminated inflammatory processes?

BACKGROUND

Fatigue is a disabling symptom of multiple sclerosis. Its biological causes are still poorly understood. Several years ago, we proposed that fatigue might be the subjective representation of inflammatory processes. An important step for a straight-forward evaluation of our model would be to show that the level of fatigue is associated with vagal activation. The heart rate is under partial control of the vagus nerve. Using power spectrum analysis allows to separate, at least partly, sympathetic and parasympathetic impact on heart rate variability.

METHODS

This narrative review summarizes the evidence for heart rate variability changes in MS patients, their relationship with fatigue and disease course. To do this, we conducted a literature search, including 45 articles relevant to the topic treated in this review.

RESULTS

We illustrate that (1) inflammation leads to a change in cardiac behavior during acute and chronic phases, both in animals and in humans; (2) MS patients show changes of heart rate variability (HRV) that resemble those during acute and chronic inflammation due to multiple causes; (3) existing evidence favors a set of specific predictions about fatigue and parallel HRV changes; and (4) that MS-related brainstem lesions or neurological impairments do not completely explain HRV changes, leaving enough place for an explanatory relation between HRV and fatigue.

DISCUSSION

We discuss the results of this review in relation to our model of fatigue and propose several observational and experimental studies that could be conducted to gain a better insight into whether fatigue and HRV can be interpreted as a common pathway, both reflecting activated autoimmune processes in MS patients.

Cognitive fatigue-related sensory gating deficits in people with multiple sclerosis

BACKGROUND

Cognitive fatigue is highly prevalent in people with multiple sclerosis (pwMS) and significantly limits their quality of life. Fatigue can be subdivided into a subjective feeling of constant (trait) or current (state) exhaustion, as well as an objective performance decline, also known as fatigability. However, the current fatigue diagnosis in pwMS is purely subjective, leaving fatigability mostly unattended. Sensorimotor and sensory gating deficits have recently been described as possible objective markers for fatigability in healthy subjects. Thus, this study aimed to investigate the potential of prepulse inhibition (PPI) ratios and the P50 sensory gating suppression as surrogate markers for cognitive fatigue in pwMS.

METHODS

PPI and P50 sensory gating ratios were assessed before and after a 30-min fatigability-inducing AX- continuous performance task. Subjective trait fatigue was operationalized via self-report questionnaires, subjective state fatigue via visual analog scales (VAS), and fatigability via the change in both gating ratios. The data were analyzed using Linear Mixed Models and Pearson correlations.

RESULTS

We included 18 pwMS and 20 healthy controls (HC) in the final analyses. The task-induced fatigability was more pronounced in pwMS. While the initial PPI and P50 ratios were similar in both groups, P50 sensory gating was significantly disrupted after fatigability induction in pwMS. PPI, on the other hand, decreased in both groups. Moreover, initial P50 sensory gating ratios were negatively associated with subjective trait fatigue in pwMS, indicating that higher trait fatigue is associated with disrupted sensory gating. Finally, fatigability-related changes in P50 sensory gating were associated with the changes in VAS ratings, but only in HC.

CONCLUSIONS

This study demonstrated that P50 sensory gating is a promising objective fatigue and fatigability parameter. Importantly, P50 sensory gating correlated with subjective trait and state fatigue ratings. Our results extend the subjective fatigue diagnosis and broaden the understanding of pathophysiological neuronal mechanisms in MS-related fatigue. This is the first study to present fatigue-related disruption of sensory gating in pwMS.

Insular cortex neurons encode and retrieve specific immune responses

Increasing evidence indicates that the brain regulates peripheral immunity, yet whether and how the brain represents the state of the immune system remains unclear. Here, we show that the brain's insular cortex (InsCtx) stores immune-related information. Using activity-dependent cell labeling in mice (Fos^TRAP), we captured neuronal ensembles in the InsCtx that were active under two different inflammatory conditions (dextran sulfate sodium [DSS]-induced colitis and zymosan-induced peritonitis). Chemogenetic reactivation of these neuronal ensembles was sufficient to broadly retrieve the inflammatory state under which these neurons were captured. Thus, we show that the brain can store and retrieve specific immune responses, extending the classical concept of immunological memory to neuronal representations of inflammatory information.

Fatigue in Survivors of Autoimmune Encephalitis

BACKGROUND AND OBJECTIVES

To evaluate the impact of fatigue after autoimmune encephalitis, determine associations with patients' characteristics, and identify factors that contribute to its development.

METHODS

In a first cohort recruited via several encephalitis support organizations, self-reported questionnaires were used to evaluate fatigue, depression, and sleep quality in adults after autoimmune encephalitis. In a second cohort where more in-depth clinical characterization could be performed, adults with encephalitis from 2 tertiary hospitals were evaluated using the same questionnaires. Patients' characteristics were retrospectively captured.

RESULTS

In the first cohort (mean [SD] age; 43 [16] years, 220 [65%] female), 220 of 338 participants (65%) reported fatigue, 175 of 307 (57%) depression, and 211 of 285 (74%) poor sleep quality. In the second cohort (48 [19] years; 43 [50%] women), 42 of 69 participants (61%) reported fatigue, whereas 23 of 68 (34%) reported depression and 44 of 66 (67%) poor sleep quality, despite more than 80% having "good" modified Rankin scale (mRS) scores (0-2). Individuals with anti-NMDA receptor encephalitis reported lower fatigue scores than those with other autoimmune encephalitis types. In a multivariate analysis examining factors at discharge that might predict fatigue scores, only anti-NMDA receptor encephalitis was a (negative) predictor of fatigue and remained so when potential confounders were included.

DISCUSSION

The impact of fatigue after autoimmune encephalitis is prominent and not fully accounted for by depression or sleep quality, nor adequately captured by mRS scores for disability. Fatigue is pervasive across autoimmune encephalitis, although lower scores are reported in anti-NMDA receptor encephalitis. Fatigue should be screened routinely, considered as an outcome measure in clinical trials, and further studied from a mechanistic standpoint.

The Proper Diet and Regular Physical Activity Slow Down the Development of Parkinson Disease

From year to year, we know more about neurodegeneration and Parkinson’s disease (PD). A positive influence of various types of physical activity is more often described in the context of neuroprotection and prevention as well as the form of rehabilitation in Parkinson’s patients. Moreover, when we look at supplementation, clinical nutrition and dietetics, we will see that balancing consumed products and supplementing the vitamins or minerals is necessary. Considering the biochemical pathways in skeletal muscle, we may see that many researchers desire to identify molecular mediators that have an impact through exercise and balanced diet on human health or development of the neurodegenerative disease. Therefore, it is mandatory to study the potential mechanism(s) related to diet and factors resulted from physical activity as molecular mediators, which play a therapeutic role in PD. This review summarizes the available literature on mechanisms and specific pathways involved in diet-exercise relationship and discusses how therapy, including appropriate exercises and diet that influence molecular mediators, may significantly slow down the progress of neurodegenerative processes. We suggest that a proper diet combined with physical activity will be a good solution for psycho-muscle BALANCE not only in PD but also in other neurodegenerative diseases.

Mindfulness training during brief periods of hospitalization in multiple sclerosis (MS): beneficial alterations in fatigue and the mediating role of depression

OBJECTIVES

Persons with MS (PwMS) are frequently affected by fatigue and depression. Mindfulness-based interventions may reduce these symptoms in PwMS and consequently their application has been extended to various settings. Only few efforts have been made to explore effects of short-term mindfulness training during brief periods of hospitalization. In the current study, the feasibility and potential effects of short-term mindfulness training on depression, fatigue, rumination and cognition were explored in PwMS in an acute-care hospital setting. Based on previous work, it was further examined whether the relation between trait mindfulness and fatigue prior to and following the intervention was mediated by depression and whether a mediation effect was also observable throughout the intervention.

METHODS

A short-term mindfulness training protocol was developed, tailored to the requirements of the acute-care setting. Subsequently, 30 PwMS were recruited sequentially and received mindfulness training during the routine clinical process (median duration in hospital: eight days, number of sessions: four). Participants completed relevant self-report measures (depression, fatigue, rumination) and a neuropsychological assessment before and after training.

RESULTS

Participants reported significantly increased trait mindfulness and decreased depression and fatigue following the intervention. Respective change scores were highly correlated so that increased trait mindfulness was associated with decreased symptoms. In the rumination domain, patients reported a tendency for an increased adaptive ability to engage in distractive behavior during arising negative mood. Other measures of trait rumination and cognition remained relatively stable. Results of the mediation analyses indicated that depression mediated the negative relationship between trait mindfulness and fatigue symptoms at pre and post assessments. With regards to the change scores, an association between mindfulness and cognitive fatigue ceased to be significant when depression was controlled, albeit in this case, the mediation effect did not reach significance.

CONCLUSION

Results of the current study indicate that short-term mindfulness training during brief periods of hospitalization may be beneficial for PwMS. They further complement previous work by identifying depression as a potential mediator of the antagonistic relationship between mindfulness and fatigue. Based on the current exploratory study, future trials are warranted to address this mechanism of mindfulness training in more detail.

Distinguishing between Fatigue and Fatigability in Multiple Sclerosis

Fatigue is one of the most common debilitating symptoms reported by persons with multiple sclerosis (MS). It reflects feelings of tiredness, lack of energy, low motivation, and difficulty in concentrating. It can be measured at a specific instant in time as a perception that arises from interoceptive networks involved in the regulation of homeostasis. Such ratings indicate the state level of fatigue and likely reflect an inability to correct deviations from a balanced homeostatic state. In contrast, the trait level of fatigue is quantified in terms of work capacity (fatigability), which can be either estimated (perceived fatigability) or measured (objective fatigability). Clinically, fatigue is most often quantified with questionnaires that require respondents to estimate their past capacity to perform several cognitive, physical, and psychosocial tasks. These retrospective estimates provide a measure of perceived fatigability. In contrast, the change in an outcome variable during the actual performance of a task provides an objective measure of fatigability. Perceived and objective fatigability do not assess the same underlying construct. Persons with MS who report elevated trait levels of fatigue exhibit deficits in interoceptive networks (insula and dorsal anterior cingulate cortex), including increased functional connectivity during challenging tasks. The state and trait levels of fatigue reported by an individual can be modulated by reward and pain pathways. Understanding the distinction between fatigue and fatigability is critical for the development of effective strategies to reduce the burden of the symptom for individuals with MS.

Trait mindfulness is primarily associated with depression and not with fatigue in multiple sclerosis (MS): implications for mindfulness-based interventions

Objectives

Persons with MS (PwMS) often display symptoms of depression and fatigue. Mindfulness-based interventions are known to counteract these symptoms. However, to-date the exact relations between trait mindfulness, depression and fatigue remain to be examined. Fatigue is generally regarded as a symptom immanent to the disease and as a direct neurobiological consequence of increased cytokine levels and cortical atrophy. In depression on the other hand, psychosocial factors in the context of adaptation difficulties are probably of higher relevance. Hence, one may argue that mindfulness, as a trait that promotes successful adaption, may show a strong negative association with depression and a relatively minor negative association with fatigue in PwMS.

Methods

In the current study, the association between self-reported trait mindfulness, fatigue and depression was examined in a sample of 69 PwMS.

Results

Trait mindfulness showed highly significant negative correlations with both, depression and fatigue. Mediation analyses however, revealed that depression mediated the relation between mindfulness and fatigue.

Conclusion

It may be concluded that in PwMS, trait mindfulness shows a genuine negative association with depression, but that it is only secondarily associated with fatigue. Implications for mindfulness-based interventions in MS are discussed. Based on the results of the current study, it may be feasible to promote the acceptance of default fatigue symptoms, instead of an actual reduction of fatigue symptoms.

Does oral salbutamol improve fatigue in multiple sclerosis? A pilot placebo-controlled study

BACKGROUND

Because MS-related fatigue could be associated with enhanced proinflammatory cytokine production, drugs with immunomodulatories properties, such as salbutamol, may represent an alternative treatment. We aimed to evaluate the effect of salbutamol on MS-related fatigue.

METHODS

Thirty patients with relapsing-remitting MS who were between 18 and 69 years old, and suffering from fatigue, were evaluated with the Fatigue Severity Scale (FSS) and the Brazilian version of the neurological fatigue index for multiple sclerosis (NFI/MS-BR). They received salbutamol 2 mg twice a day or a placebo in a pilot randomized, double-masked placebo-controlled trial. The primary outcome was the change in the FSS score at the end of 90 days. The secondary outcome was the efficacy, represented by changes in their scores on the NFI/MS-BR subdomains (in the same period) and the Expanded Disability Status Scale (EDSS) at the end of 90 days.

RESULTS

Thirty subjects were allocated to receive either salbutamol (14) or a placebo (16). There was no superiority of salbutamol over the placebo in the FSS outcome at 30 (p ==0.498), 60 (p = 0.854) and 90 (p = 0.240) days. There was no a significant decrease in the proportion of patients with severe or moderate fatigue in the salbutamol group at the end of the follow-up. The scores on the NFI/MS-BR and its subscales did not improve significantly with treatment. No significant difference was observed in the EDSS outcome (p = 0.313). No serious adverse events were found. An increase in heart rate was evident in the salbutamol group only in the first 30 days, but without statistical significance in relation to placebo (p = 0.077).

CONCLUSION

Treatment with salbutamol does not improve fatigue in patients with relapsing-remitting MS.

Autonomic dysfunctions in multiple sclerosis: Challenges of clinical practice (Review)

Multiple sclerosis, demyelinating, inflammatory, degenerative, and chronic disease, raises many challenges in terms of disease management. The autonomic nervous system is affected by neuroinflammation but also contributes to its maintenance and the evolution of the disease. Multiple sclerosis interfering with parasympathetic or sympathetic modulation may influence the immune response. Less attention is paid to autonomic dysfunctions, although they produce a serious impact on the quality of life. In addition to motor disabilities, patients also have non-motor dysfunctions. Regardless of its clinical forms, patients with multiple sclerosis may have autonomous disturbances such as bladder, sexual, cardiovascular, thermoregulatory, gastrointestinal dysfunction and fatigue. These must be identified based on medical history, clinical symptoms, and specific paraclinical tests. In addition to the multitude of immunomodulatory therapeutic agents that influence the progression of the disease, the therapy of autonomic dysfunctions remains difficult to address. However, their identification and treatment lead to increased quality of patient management and avoid complications of this disease.

The association between systemic inflammation and cognitive performance in healthy adults

BACKGROUND

Several studies have indicated that mild systemic inflammation is associated with the risk of cognitive impairment. However, not every cognitive domain has been evaluated to have a correlation with peripheral inflammation in healthy individuals. Therefore, we aimed to investigate the association between C-reactive protein (CRP) as a marker of peripheral inflammation with various domains of cognition in healthy adults.

METHOD

This study consisted of 216 healthy native German adults (138 males and 78 females, mean age: 39.12 ± 20.19 years) from "Leipzig Study for Mind-Body-Emotion Interactions" (LEMON) database. After the initial assessment and conducting the cognitive battery, a blood sample was collected and CRP level was evaluated. Patients were categorized into three groups based on their CRP level. Subsequently, demographic and cognitive features were compared across three groups and to confirm the association between CRP level and cognitive performance, general linear models (GLM) were applied.

RESULTS

All California Verbal Learning Task (CVLT)-evaluated aspects of memory performance were inversely associated with CRP level, some of which remained significant after the adjustment for age, gender, education, smoking status and body mass index. Moreover, GLM analysis indicated that mean reaction time of the Test of Attentional Performance-Alertness (TAP-A) test (with and without signal) was also significantly associated with CRP level.

CONCLUSION

The current study indicated that healthy subjects with higher levels of CRP exhibit poorer performance in verbal learning memory and general wakefulness domains of cognition.

Pilot randomized active-placebo-controlled trial of low-dose ketamine for the treatment of multiple sclerosis-related fatigue

BACKGROUND

Fatigue is the most common symptom of MS and has no effective pharmacotherapy.

OBJECTIVE

To determine the tolerability, safety, and efficacy of low-dose ketamine infusion for MS-related fatigue.

METHODS

In this double-blind, randomized, active-placebo-controlled trial, 18 subjects with multiple sclerosis (MS) and reported fatigue received a single intravenous infusion of ketamine (0.5 mg/kg) or midazolam (0.05 mg/kg). The primary outcome was change in Daily Fatigue Severity (DFS) for 7 days following the infusion. Secondary outcomes included Fatigue Severity Scale (FSS) and Modified Fatigue Impact Scale (MFIS) measured up to day 28 post-infusion. We analyzed changes in all outcomes using mixed-effect models.

RESULTS

In total, 18 participants were enrolled; 67% participants received ketamine. Side effects of ketamine were transient. No change in the DFS was observed after 7 days (-0.10 point; 95% confidence interval (CI): -0.32, 0.12; p = 0.40). We observed a trend in reduced FSS scores at 1 week (-5.2 points; 95% CI: -10.4, 0.14; p = 0.06) and a clinically and statistically significant reduction in MFIS score at day 28 (-13.5 point; 95% CI: -25.0, -1.98; p = 0.04).

CONCLUSIONS

Ketamine infusions were safe and well-tolerated. While no change in DFS after 7 days was observed, secondary analyses suggest a benefit of ketamine infusion for reduction of longer term fatigue severity in people with MS.

Mild Inflammation in Healthy Males Induces Fatigue Mediated by Changes in Effective Connectivity Within the Insula

BACKGROUND

Systemic inflammation is associated with sickness behaviors such as low mood and fatigue. Activity patterns within the insula are suggested to coordinate these behaviors but have not been modeled. We hypothesized that mild systemic inflammation would result in changes in effective connectivity between the viscerosensory and the visceromotor regions of the insula.

METHODS

We used a double-blind, crossover design to randomize 20 male subjects to receive either a Salmonella typhi vaccine or a placebo saline injection at two separate sessions. All participants underwent a resting-state functional magnetic resonance scan 3 hours after injection. We determined behavioral and inflammatory changes, using the Profile of Mood States questionnaire and interleukin-6 levels. We extracted effective connectivity matrices between bilateral mid/posterior (viscerosensory) and anterior (visceromotor) insular cortices using spectral dynamic causal modeling. We applied parametric empirical Bayes and mediation analysis to determine a vaccination effect on effective connectivity and whether this mediated behavioral changes.

RESULTS

The vaccine condition was associated with greater interleukin-6 levels and greater fatigue 3 hours after the injection. Activity within the right mid/posterior insula increased the activity within the bilateral anterior insular regions. This connectivity was augmented by vaccination over a 99% posterior confidence threshold. The right mid/posterior insula-to-left anterior insula connectivity was significantly associated with fatigue and mediated the association between inflammation and increased fatigue scores.

CONCLUSIONS

These results demonstrate that increased effective connectivity between specific nodes of the insula can model and mediate the association between inflammation and fatigue in males.

Cognitive Fatigability is Independent of Subjective Cognitive Fatigue and Mood in Multiple Sclerosis

BACKGROUND

Sustained cognitive testing is used to detect cognitive fatigability and is often considered a substitute for subjective cognitive fatigue (CF). However, the relationship between cognitive fatigability and subjective CF in people with multiple sclerosis (PwMS) remains undetermined.

OBJECTIVE

To explore potential associations between fatigability induced by sustained cognitive testing and subjective CF in PwMS.

METHODS

We gave 120 PwMS and 60 demographically matched, healthy individuals the Beck Depression Inventory-FastScreen (BDI-FS) to measure mood and the Modified Fatigue Impact Scale to measure CF. In addition, we used the Quotient ADHD Test, a sustained attention test, to measure cognitive fatigability. We also explored potential correlations between the individuals' performance on the sustained attention test and thalamic volume using recent MRI scans.

RESULTS

Forty-one (34.2%) of the PwMS exhibited cognitive fatigability. These 41 were found to be significantly older (P=0.006), had been diagnosed with the disease for longer (P=0.03), had higher scores (P<0.001) on the Expanded Disability Status Scale, and had reduced thalamic volume (P=0.04) compared with the 79 (65.8%) PwMS not exhibiting cognitive fatigability. The PwMS exhibiting cognitive fatigability scored similarly on the BDI-FS (P=0.21) and self-reported similar rates of CF (P=0.62) as the PwMS not exhibiting cognitive fatigability.

CONCLUSION

Cognitive fatigability induced by sustained cognitive testing is not an accurate clinical alternative to subjective CF. This study provides evidence to support cognitive fatigability and CF in PwMS as two distinct concepts.

Fatigue in multiple sclerosis: Does the functional or structural damage prevail?

Fatigue in multiple sclerosis (MS) is a highly invalidating symptom, lacking efficacious drugs. This topical review aims at assessing the signs in the literature of functional versus structural damage prevalence at the origin of MS fatigue by focusing on papers that assessed the two counterparts in the same patients, paying attention that the fatigue levels do not correlate with clinical severity. We summarize and discuss evidence of increased levels of fatigue occurring together with the alterations of functional connectivity at multiple levels, in the absence of any relationship with lesion load and local atrophy of the involved structures. Specifically, neuronal communication mainly altered in the corticomuscular synchronizations, between hemispheric homologs and in the resting-state networks involved in emotion (cingulate cortex) and effort-reward balance (striatum and inferior parietal lobule). Finally, given the functional prevalence in neuronal network alterations at the origin of fatigue in MS, we highlight the relevance of developing treatments aiming at compensating the neuronal electric communication dysfunctions.

Fatigue in multiple sclerosis is associated with multimodal interoceptive abnormalities

BACKGROUND

Fatigue ranks among the most common and disabling symptoms in multiple sclerosis (MS). Recent theoretical works have surmised that this trait might be related to alterations across interoceptive mechanisms. However, this hypothesis has not been empirically evaluated.

OBJECTIVES

To determine whether fatigue in MS patients is associated with specific behavioral, structural, and functional disruptions of the interoceptive domain.

METHODS

Fatigue levels were established via the Modified Fatigue Impact Scale. Interoception was evaluated through a robust measure indexed by the heartbeat detection task. Structural and functional connectivity properties of key interoceptive hubs were tested by magnetic resonance imaging (MRI) and resting-state functional MRI. Machine learning analyses were employed to perform pairwise classifications.

RESULTS

Only patients with fatigue presented with decreased interoceptive accuracy alongside decreased gray matter volume and increased functional connectivity in core interoceptive regions, the insula, and the anterior cingulate cortex. Each of these alterations was positively associated with fatigue. Finally, machine-learning analysis with a combination of the above interoceptive indices (behavioral, structural, and functional) successfully discriminated (area under the curve > 90%) fatigued patients from both non-fatigued and healthy controls.

CONCLUSION

This study offers unprecedented evidence suggesting that disruptions of neurocognitive markers subserving interoception may constitute a signature of fatigue in MS.

Fatigue in Multiple Sclerosis is related to relapses, autonomic dysfunctions and introversion: A quasi-experimental study

BACKGROUND

Fatigue in Multiple Sclerosis (MS) might be partially due to inflammatory processes. If so, relapses should increase the fatigue level.

METHODS

Two groups of MS patients participated in this study. One suffered from a relapse and was treated by Methylprednisolone. The other group experienced a deterioration of their neurological condition but no relapse and received neurological rehabilitation. We assessed fatigue before admission, at admission and after discharge (t1, t2, t3). Furthermore, autonomic dysfunctions, depressive mood, apathy and extraversion were assessed at admission. Changes in fatigue were analysed with ANCOVAs and fatigue levels were analysed with regression analyses using clinical data and scores for depressive mood, apathy, extraversion and autonomic dysfunctions.

RESULTS

Only patients suffering from a relapse showed a significant increment in fatigue from t1 to t2. Regression analyses revealed that autonomic dysfunctions and introversion best explained the fatigue level.

CONCLUSIONS

This study shows that a relapse is accompanied by an increase in MS-related fatigue. Moreover, autonomic dysfunctions and introversion, more than depression and apathy, play a major role in the explanation of MS-related fatigue. This finding represents additional evidence for the relationship between inflammation, vagal afferent signaling, autonomic dysfunctions, introversion and the feeling of MS-related fatigue.

Association of chronic inflammation and perceived stress with abnormal functional connectivity in brain areas involved with interoception in hepatitis C patients

BACKGROUND

Sickness behavioral changes elicited by inflammation may become prolonged and dysfunctional in patients with chronic disease, such as chronic hepatitis C (CHC). Neuroimaging studies show that the basal ganglia and insula are sensitive to systemic inflammation.

AIM

To elucidate the clinical and neurobiological aspects of prolonged illnesses in patients with CHC.

METHODS

Thirty-five CHC patients not treated with interferon-α or other antiviral therapy, and 30 control subjects matched for age and sex, were evaluated for perceived stress (perceived stress scale; PSS), depression (PHQ-9), fatigue and irritability through a visual analog scale (VAS), as well as serum levels of interleukin-6 (IL-6), prostaglandin E₂ (PGE₂) and oxidative stress markers. Functional MRI was performed, measuring resting-state functional connectivity using a region-of-interest (seed)-based approach focusing on the bilateral insula, subgenual anterior cingulate cortex and bilateral putamen. Between-group differences in functional connectivity patterns were assessed with two-sample t-tests, while the associations between symptoms, inflammatory markers and functional connectivity patterns were analyzed with multiple regression analyses.

RESULTS

CHC patients had higher PSS, PHQ-9 and VAS scores for fatigue and irritability, as well as increased IL-6 levels, PGE₂ concentrations and antioxidant system activation compared to controls. PSS scores positively correlated with functional connectivity between the right anterior insula and right putamen, whereas PHQ-9 scores correlated with functional connectivity between most of the seeds and the right anterior insula. PGE₂ (positively) and IL-6 (negatively) correlated with functional connectivity between the right anterior insula and right caudate nucleus and between the right ventral putamen and right putamen/globus pallidus. PGE₂ and PSS scores accounted for 46% of the variance in functional connectivity between the anterior insula and putamen.

CONCLUSIONS

CHC patients exhibited increased perceived stress and depressive symptoms, which were associated with changes in inflammatory marker levels and in functional connectivity between the insula and putamen, areas involved in interoceptive integration, emotional awareness, and orientation of motivational state.

Cognitive Fatigue in Multiple Sclerosis: An Objective Approach to Diagnosis and Treatment by Transcranial Electrical Stimulation

Cognitive fatigue is one of the most frequent symptoms in multiple sclerosis (MS), associated with significant impairment in daily functioning and quality of life. Despite its clinical significance, progress in understanding and treating fatigue is still limited. This limitation is already caused by an inconsistent and heterogeneous terminology and assessment of fatigue. In this review, we integrate previous literature on fatigue and propose a unified schema aiming to clarify the fatigue taxonomy. With special focus on cognitive fatigue, we survey the significance of objective behavioral and electrophysiological fatigue parameters and discuss the controversial literature on the relationship between subjective and objective fatigue assessment. As MS-related cognitive fatigue drastically affects quality of life, the development of efficient therapeutic approaches for overcoming cognitive fatigue is of high clinical relevance. In this regard, the reliable and valid assessment of the individual fatigue level by objective parameters is essential for systematic treatment evaluation and optimization. Transcranial electrical stimulation (tES) may offer a unique opportunity to manipulate maladaptive neural activity underlying MS fatigue. Therefore, we discuss evidence for the therapeutic potential of tES on cognitive fatigue in people with MS.

Capturing fatigue parameters: The impact of vagal processing in multiple sclerosis related cognitive fatigue

BACKGROUND

Causes of fatigue in Multiple Sclerosis remain elusive. Recently, we developed a model linking cognitive fatigue to inflammatory processes based on a neuroinflammatory reflex-arc instantiated by the vagus nerve. The relation between experienced autonomic dysfunctions, based on vagal processing, and cognitive fatigue is well-known, but an examination of the association of objectively measured vagal activity and cognitive fatigue is missing. An attempt was made to collect behavioral and physiological evidence that can be associated with experienced autonomic dysfunctions and fatigue in Multiple Sclerosis patients.

METHODS

Behavioral performance (response bias) and autonomic functioning (Heart rate variability and Skin conductance level) during an acoustic vigilance task were investigated in 53 Multiple Sclerosis patients. We assessed trait fatigue (independent from task), and time-on-task related increase of fatigue. Regression analysis was used to predict the fatigue status with physiological and behavioral scores.

RESULTS

Response bias, indicating a reduced responsiveness, and high and very low frequency components of Heart rate variability, indicating an increased parasympathetic activity, contribute to the regression of trait fatigue. Reduced Heart rate variability (SDNN) and increased parasympathetic activity (pNN50) remained in the regression model predicting time-on-task fatigue.

CONCLUSION

Cognitive fatigue in MS is related to parasympathetic activity and reduced responsiveness, supporting our model representing fatigue as inflammatory processes in the brain. Standardized subjective and objective autonomous dysfunction measures might be considered as additional assessments in MS.

Evaluation of MS related central fatigue using MR neuroimaging methods: Scoping review

BACKGROUND

Fatigue is a common and debilitating symptom in multiple sclerosis (MS). Over the past decade, a growing body of research has focussed on the pathophysiological mechanisms underlying central (cognitive and physical) fatigue in MS. The precise mechanisms causing fatigue in MS patients are complex and poorly understood, and may differ between patients. Advanced quantitative magnetic resonance imaging (MRI) techniques allow for objective assessment of disease pathology and have been used to characterise the pathophysiology of central fatigue in MS.

OBJECTIVE

To systematically review the existing literature of MRI-based studies assessing the pathophysiological mechanisms of MS-related central fatigue.

METHODS

A systematic literature search of four major databases (PubMed, Medline, Embase, Scopus and Google Scholar) was conducted to identify MRI-based studies of MS-related fatigue published in the past 20 years. Studies using the following MRI-based methods were included: structural (lesion load/atrophy), T1 relaxation time/magnetisation transfer ratio (MTR), diffusion tensor imaging (DTI), functional MRI (fMRI) and magnetic resonance spectroscopy (MRS).

RESULTS

A total of 92 studies were identified as meeting the search criteria and included for review. Structurally, regional gray/white matter atrophy, cortical thinning, decreased T1 relaxation times and reduced fractional anisotropy were associated with central fatigue in MS. Functionally, hyperactivity and reduced functional connectivity in several regional areas of frontal, parietal, occipital, temporal and cerebellum were suggested as causes of central fatigue. Biochemically, a reduction in N-acetyl aspartate/creatine and increased (glutamine+glutamate)/creatine ratios were correlated with fatigue severity in MS.

CONCLUSION

Several advanced quantitative MRI methods have been employed in the study of central fatigue in MS. Central fatigue in MS is associated with macro/microstructural and functional changes within specific brain regions (frontal, parietal, temporal and deep gray matter) and specific pathways/networks (cortico-cortical and cortico-subcortical). Alternations in the cortico-striatal-thalamocortical (CSTC) loop are correlated with the development of fatigue in MS patients.

Influence of different rehabilitative aerobic exercise programs on (anti-) inflammatory immune signalling, cognitive and functional capacity in persons with MS - study protocol of a randomized controlled trial

BACKGROUND

Studies have shown positive effects of therapeutic exercise on motor- and cognitive function as well as on psychosocial outcomes in persons with multiple sclerosis (MS). A reduction of inflammatory stress through physical exercise has been suspected as one key mechanism, mediating the positive effects of exercise in the context of MS. The primary objective of this trial is to investigate the acute and chronic effects of different exercise modalities on (anti-)inflammatory immune signalling as well as on cognitive and functional capacity in persons with MS.

METHODS

A two armed single-blind randomized controlled design will investigate 72 persons with relapsing remitting or secondary progressive MS (EDSS 3.0-6.0), during 3 weeks of inpatient rehabilitation. Participants will be randomized into either a high-intensity interval training (HIIT) or a moderate continuous training group; the latter represents the local standard therapy (ST). Both groups will exercise 3x per week. The HIIT group will perform 5 × 1.5-min high-intensive exercise bouts at 95-100% of their maximum heart rate (HRmax) followed by active breaks of unloaded pedalling (60% HRmax) for 2 min. In contrast, the ST group will exercise for 24 min continuously at 65% of HRmax. The proportion of circulating regulatory T-cells will be measured as primary outcome. Secondary outcomes comprise numbers and proportions of further immune cells including Th17-cells, soluble factors ((anti-) inflammatory cytokines, tryptophan metabolites), endurance capacity, cognitive performance, processing skills for activities of daily living, fatigue, depression and healthcare-related quality of life. Outcomes will be assessed before (T0) and after (T3) the 3-week exercise intervention program. Blood samples of T0 will be taken immediately before the first exercise session. Additionally, blood samples for the soluble factors will be collected immediately after (T1) and three hours (T2) after the first exercise session of each group.

DISCUSSION

This study will be the first to investigate both acute and chronic effects of aerobic exercise on immune function and disease associated biomarkers in persons with MS. Combining biological analyses with cognitive and functional capacity assessments may contribute to a better understanding of responses to rehabilitative training, needed to improve exercise recommendations for persons with MS.

TRIAL REGISTRATION

This trial was prospectively registered at ClinicalTrials.gov ( NCT03652519 ; 29 August 2018).

Altered neural signatures of interoception in multiple sclerosis

Multiple sclerosis (MS) patients present several alterations related to sensing of bodily signals. However, no specific neurocognitive impairment has yet been proposed as a core deficit underlying such symptoms. We aimed to determine whether MS patients present changes in interoception-that is, the monitoring of autonomic bodily information-a process that might be related to various bodily dysfunctions. We performed two studies in 34 relapsing-remitting, early-stage MS patients and 46 controls matched for gender, age, and education. In Study 1, we evaluated the heartbeat-evoked potential (HEP), a cortical signature of interoception, via a 128-channel EEG system during a heartbeat detection task including an exteroceptive and an interoceptive condition. Then, we obtained whole-brain MRI recordings. In Study 2, participants underwent fMRI recordings during two resting-state conditions: mind wandering and interoception. In Study 1, controls exhibited greater HEP modulation during the interoceptive condition than the exteroceptive one, but no systematic differences between conditions emerged in MS patients. Patients presented atrophy in the left insula, the posterior part of the right insula, and the right anterior cingulate cortex, with abnormal associations between neurophysiological and neuroanatomical patterns. In Study 2, controls showed higher functional connectivity and degree for the interoceptive state compared with mind wandering; however, this pattern was absent in patients, who nonetheless presented greater connectivity and degree than controls during mind wandering. MS patients were characterized by atypical multimodal brain signatures of interoception. This finding opens a new agenda to examine the role of inner-signal monitoring in the body symptomatology of MS.

Salivary IL-1ß as an Objective Measure for Fatigue in Multiple Sclerosis?

Background: The causes of fatigue in multiple sclerosis (MS) and other inflammatory disorders are not well understood. One possible cause that might explain fatigue in inflammatory disorders appears to be the immunological process itself, triggering neural activity that is experienced as fatigue.

Objectives: To investigate whether salivary IL-1ß concentration, associated with systemic inflammation, is related to subjective fatigue in MS.

Methods: 116 MS patients (62 relapsing remitting MS, 54 secondary progressive MS) and 51 healthy controls participated in this study. Salivary concentration of IL-1ß was determined using a commercially available enzyme-linked immunosorbent assay (ELISA) kit. Fatigue was assessed using various fatigue scales. We compared IL-1ß concentration between groups and performed regression analyses to investigate which variables best predict fatigue scores.

Results: We found that the IL-1ß concentration best predicts fatigue scores in relapsing remitting MS patients, even though the IL-1ß concentration did not differ significantly between relapsing remitting MS patients and healthy controls. Secondary progressive MS patients showed a somewhat elevated IL-1ß concentration compared to relapsing remitting MS patients and healthy controls. Furthermore, disease modifying treatment had a significant effect on the IL-1ß concentration, with treated patients showing a lower IL-1ß concentration than non-treated patients.

Conclusions: The present study points to a significant relation between the proinflammatory cytokine IL-1ß and fatigue in relapsing remitting MS patients. It also suggests a potential effect of disease modifying treatment on the peripheral IL-1ß concentration.

Sex differences in how inflammation affects behavior: What we can learn from experimental inflammatory models in humans

Human models demonstrate that experimental activation of the innate immune system has profound effects on brain activation and behavior, inducing fatigue, worsened mood and pain sensitivity. It has been proposed that inflammation is a mechanism involved in the etiology and maintenance of depression, chronic pain and long-term fatigue. These diseases show a strong female overrepresentation, suggesting that a better understanding of sex differences in how inflammation drives behavior could help the development of individualized treatment interventions. For this purpose, we here review sex differences in studies using experimental inflammatory models to investigate changes in brain activity and behavior. We suggest a model in which inflammation accentuates sex differences in brain networks and pre-existing vulnerability factors. This effect could render women more vulnerable to the detrimental effects of immune-to-brain communication over time. We call for systematic and large scale investigations of vulnerability factors for women in the behavioral response to inflammation.

Into the Moment: Does Mindfulness Affect Biological Pathways in Multiple Sclerosis?

Mindfulness was introduced in the Western world by Jon Kabat-Zinn in 1979. He defined it as "awareness that arises through paying attention, on purpose, in the present moment, non-judgmentally." Since then, research on mindfulness-based interventions (MBIs) has increased exponentially both in health and disease, including in patients with neurodegenerative diseases such as dementia and Parkinson's disease. Research on the effect of mindfulness and multiple sclerosis (MS) only recently gained interest. Several studies completed since 2010 provided evidence that mindfulness improves quality of life (QoL), depression and fatigue in MS patients. In addition to patient-reported outcome measures, potential effects on cognitive function have been investigated only to a very limited extent. However, research on laboratory biomarkers and neuroimaging, capable to deliver proof-of-concept of this behavioral treatment in MS, is mainly lacking. In this perspective, we illustrate possible neurobiological mechanisms, including the tripartite interaction between the brain, the immune system and neuroendocrine regulation, through which this treatment might affect multiple sclerosis symptoms. We propose to (1) include immunological and/or neuroimaging biomarkers as standard outcome measures in future research dedicated to mindfulness and MS to help explain the clinical improvements seen in fatigue and depression; (2) to investigate effects on enhancing cognitive reserve and cognitive function; and (3) to investigate the effects of mindfulness on the disease course in MS.

Brainstem dose is associated with patient-reported acute fatigue in head and neck cancer radiation therapy

BACKGROUND AND PURPOSE

Radiation (RT) dose to the central nervous system (CNS) has been implicated as a contributor to treatment-related fatigue in head and neck cancer (HNC) patients undergoing radiation therapy (RT). This study evaluates the association of RT dose to CNS structures with patient-reported (PRO) fatigue scores in a population of HNC patients.

MATERIALS AND METHODS

At pre-RT (baseline), 6th week of RT, and 1-month post-RT time points, Multidimensional Fatigue Inventory (MFI-20) scores were prospectively obtained from 124 patients undergoing definitive treatment for HNC. Medulla, pons, midbrain, total brainstem, cerebellum, posterior fossa, and pituitary dosimetry were evaluated using summary statistics and dose-volume histograms, and associations with MFI-20 scores were analyzed.

RESULTS

Maximum dose (Dmax) to the brainstem and medulla was significantly associated with MFI-20 scores at 6th week of RT and 1-month post-RT time points, after controlling for baseline scores (p<0.05). Each 1Gy increase in medulla Dmax resulted in an increase in total MFI-20 score over baseline of 0.30 (p=0.026), and 0.25 (p=0.037), at the 6th week of RT and 1-month post-RT, respectively. Each 1Gy increase in brainstem Dmax resulted in an increase in total MFI-20 score over baseline of 0.30 (p=0.027), and 0.25 (p=0.037) at the 6th week of RT, 1-month post-RT, respectively. Statistically significant associations were not found between dosimetry for the other CNS structures and MFI-20 scores.

CONCLUSIONS

In this analysis of PRO fatigue scores from a population of patients undergoing definitive RT for HNC, maximum dose to the brainstem and medulla was associated with a significantly increased risk of acute patient fatigue.

Subjective Cognitive Fatigue and Autonomic Abnormalities in Multiple Sclerosis Patients

BACKGROUND

Cognitive fatigue and autonomic abnormalities are frequent symptoms in MS. Our model of MS-related fatigue assumes a shared neural network for cognitive fatigue and autonomic failures, i.e., aberrant vagus nerve activity induced by inflammatory processes. Therefore, they should occur in common.

OBJECTIVE

To explore the relationship between cognitive fatigue and autonomic symptoms in MS patients, using self-reported questionnaires.

METHODS

In 95 MS patients, cognitive fatigue was assessed with the Fatigue Scale for Motor and Cognitive Functions and autonomic abnormalities with the Composite Autonomic Symptom Scale-31 (COMPASS-31). We used exploratory correlational analyses and hierarchical regression analysis, controlling for age, depressive mood, disease status, and disease duration, to analyze the relation between autonomic abnormalities and cognitive fatigue.

RESULTS

The cognitive fatigue score strongly correlated with the COMPASS-31 score (r = 0.47, p < 0.001). Regression analysis revealed that a model, including the COMPASS-31 domains: pupillomotor, orthostatic intolerance, and bladder, best predict the level of cognitive fatigue (R² = 0.47, p < 0.001) after forcing the covariates into the model.

CONCLUSION

In MS patients, cognitive fatigue and autonomic dysfunction share a proportion of variance. This supports our model assuming that fatigue might be explained at least partially by inflammation-induced vagus nerve activity.

Light therapy for multiple sclerosis-associated fatigue: Study protocol for a randomized controlled trial

BACKGROUND

Fatigue is the most commonly reported symptom among multiple sclerosis (MS) patients, more than a quarter of whom consider fatigue to be their most disabling symptom. However, there are few effective treatment options for fatigue. We aim to investigate whether supplemental exposure to bright white light will reduce MS-associated fatigue.

METHODS

Eligible participants will have clinically confirmed multiple sclerosis based on the revised McDonald criteria (2010) and a score ≥36 on the Fatigue Severity Scale (FSS). Participants will be randomized 1:1 to bright white light (10,000 lux; active condition) or dim red light (<300 lux; control condition) self-administered for 1 hour twice daily. The study will include a 2-week baseline period, a 4-week treatment period, and a 4-week washout period. Participants will record their sleep duration, exercise, caffeine, and medication intake daily. Participants will record their fatigue using the Visual Analogue Fatigue Scale (VAFS) 4 times every third day, providing snapshots of their fatigue level at different times of day. Participants will self-report their fatigue severity using FSS on 3 separate visits: at baseline (week 0), following completion of the treatment phase (week 6), and at study completion (week 10). The primary outcome will be the change in the average FSS score after light therapy. We will perform an intention-to-treat analysis, comparing the active and control groups to assess the postintervention difference in fatigue levels reported on FSS. Secondary outcome measures include change in global VAFS scores during the light therapy and self-reported quality of life in the Multiple Sclerosis Quality of Life-54.

DISCUSSION

We present a study design and rationale for randomizing a nonpharmacological intervention for MS-associated fatigue, using bright light therapy. The study limitations relate to the logistical issues of a self-administered intervention requiring frequent participant self-report in a relapsing condition. Ultimately, light therapy for the treatment of MS-associated fatigue may provide a low-cost, noninvasive, self-administered treatment for one of the most prevalent and burdensome symptoms experienced by people with MS.

Disease-Induced Skeletal Muscle Atrophy and Fatigue

Numerous health problems, including acute critical illness, cancer, diseases associated with chronic inflammation, and neurological disorders, often result in skeletal muscle weakness and fatigue. Disease-related muscle atrophy and fatigue is an important clinical problem because acquired skeletal muscle weakness can increase the duration of hospitalization, result in exercise limitation, and contribute to a poor quality of life. Importantly, skeletal muscle atrophy is also associated with increased morbidity and mortality of patients. Therefore, improving our understanding of the mechanism(s) responsible for skeletal muscle weakness and fatigue in patients is a required first step to develop clinical protocols to prevent these skeletal muscle problems. This review will highlight the consequences and potential mechanisms responsible for skeletal muscle atrophy and fatigue in patients experiencing acute critical illness, cancer, chronic inflammatory diseases, and neurological disorders.

Inhibitory effects of 3α-hydroxy-lup-20(29)-en-23, 28-dioic acid on lipopolysaccharide-induced TNF-α, IL-1β, and the high mobility group box 1 release in macrophages

We investigated the anti-inflammatory effects of 3α-hydroxy-lup-20(29)-en-23, 28-dioic acid (HLEDA)-a lupane-type triterpene isolated from leaves of Acanthopanax gracilistylus W. W.Smith (AGS), as well as the underlying molecular mechanisms in lipopolysaccharide (LPS)-induced RAW264.7 cells. Our results demonstrated that HLEDA concentration-dependently reduced the production of nitric oxide (NO), significantly suppressed LPS-induced expression of TNF-α and IL-1β at the mRNA and protein levels in RAW264.7 cells. Further analysis revealed that HLEDA could reduce the secretion of High Mobility Group Box 1 (HMGB1). Additionally, the results showed that HLEDA efficiently decreased nuclear factor-kappaB (NF-κB) activation by inhibiting the degradation and phosphorylation of IκBα. These results suggest that HLEDA exerts anti-inflammatory properties in LPS-induced macrophages, possibly through inhibition of the NF-κB signaling pathway, which mediates the expression of pro-inflammatory cytokines. These results warrant further studies that would concern candidate therapy for diseases, such as fulminant hepatitis and rheumatology of triterpenoids in AGS.

Fatigue evaluation in fingolimod treated patients: An observational study

BACKGROUND

Fatigue is one of the most disabling symptoms in Multiple Sclerosis (MS) patients and is associated with a low quality of life. Fingolimod (Fg), a sphingosine 1-phosphate receptor modulator, is the first oral MS disease modifying treatment. Little is known about its effect on fatigue. To assess the impact of Fg on fatigue within the first 6 months of treatment in MS patients, we conducted a prospective, open label study, in real life setting.

METHODS

Change of Modified Fatigue Impact Scale (MFIS) between Fg treatment start and at 6 months was used as a first outcome. Secondary outcomes were changes of MFIS subscales, Fatigue severity scale (FSS) and Visual Analogic Scale of Fatigue (VAS-F) scores, RESULTS: 54 completed the study at M6. No significant change was noted in global MFIS (and neither in sub analysis of MFIS), FSS or VAS-F at M6. Patients with high level of fatigue (MFIS or ≥38) had a higher EDSS score than patients with lower level of fatigue (MFIS <38), (mean 3.3, [SD 1.6] versus 1.6 [SD1.1], p=0.0002) but showed no significant difference in MFIS evolution at M6. There was no significant statistical difference in fatigue parameters evolution at M6 within patients Nz+ or Nz-.

CONCLUSION

There is no significant impact of Fg on fatigue after 6 months of treatment.

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.

Potential pathophysiological pathways that can explain the positive effects of exercise on fatigue in multiple sclerosis: A scoping review

BACKGROUND

Fatigue is one of the most common and most disabling symptoms of multiple sclerosis (MS). It is a multidimensional and complex symptom with multifaceted origins, involving both central and peripheral fatigue mechanisms. Exercise has proven to be safe for people with MS, with cumulating evidence supporting significant reductions in fatigue. However, the potential pathophysiological pathways that can explain the positive effects of exercise on fatigue in MS remain elusive.

OBJECTIVES

The objectives were, in PwMS (1) to update the knowledge on the pathophysiology underlying primary and secondary fatigue, and (2) to discuss potential pathophysiological pathways that can explain the positive effects of exercise on MS fatigue.

METHODS

A comprehensive literature search of six databases (PubMed, Embase, Cochrane Library, PEDro, CINAHL and SPORTDiscus) was performed. To be included, the study had to 1) enroll participants with definite MS according to defined criteria, 2) assess explicit pathophysiological mechanisms related to MS fatigue, 3) be available in English, Danish or French, and 4) had undergone peer-review.

RESULTS

A total of 234 studies fulfilled the inclusion criteria. Primary MS fatigue mainly originated from a dysfunction of central nervous system neuronal circuits secondary to increased inflammation, reduced glucose metabolism, brain atrophy and diffuse demyelination and axonal lesions. Secondary MS fatigue was linked with sleep disturbances, depression, cognitive impairments, and deconditioning. Cardiovascular, immunologic, neuroendocrine, and neurotrophic changes associated with exercise may alleviate primary MS fatigue while exercise may improve secondary MS fatigue through symptomatic improvement of deconditioning, sleep disorders, and depression.

CONCLUSIONS

>30 primary and secondary pathophysiological fatigue pathways were identified underlining the multidimensionality and complexity of MS fatigue. Though the underlying key cellular and molecular cascades still have to be fully elucidated, exercise holds the potential to alleviate MS fatigue, through both primary and secondary fatigue pathways.