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.

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.

Endovascular Therapy versus Thrombolysis in Patients with Mild Strokes and Large Vessel Occlusions within the Anterior Circulation

Background

In patients with large vessel occlusions, endovascular treatment (ET) has been shown to be superior to intravenous thrombolysis (IVT) in recent trials. However, it is currently unclear if patients with mild strokes also benefit from ET.

Methods

We compared the discharge rates of good outcome (modified Rankin scale [mRS] ≤2), very good outcome (mRS 0-1), symptomatic intracranial hemorrhages (SICH), and infarct sizes in patients with mild strokes (admission National Institutes of Health Stroke Scale ≤10) and distal intracranial carotid artery, M1, and M2 occlusions during two time periods.

Results

From 1/2008 to 10/2012 160 patients (mean age: 72 ± 12 years) were treated with IVT, and from 11/2012 to 11/2016 145 patients (mean age: 71 ± 13 years,) received ET with or without IVT. The clinical results were comparable between both treatment groups (59% after ET vs. 56% after IVT, p = 0.5 for an mRS 0-2) and (38% after ET vs. 32% after IVT, p = 0.3 for an mRS 0-1). In the subgroup of patients with an mRS ≤6, the early outcome did not differ significantly between ET and IVT either. The rates of SICH as well as the infarct sizes were not significantly different after ET compared with IVT.

Conclusion

Compared with IVT, the routine use of ET did not significantly improve the early clinical or radiological outcome in patients with mild strokes and anterior circulation large vessel occlusions. Further randomized trials are urgently needed to determine the role of ET in this cohort.

Improving everyday memory performance after acquired brain injury: An RCT on recollection and working memory training

OBJECTIVE

To show the effectiveness of a combined recognition and working memory training on everyday memory performance in patients suffering from organic memory disorders.

METHOD

In this double-blind, randomized controlled Study 36 patients with organic memory impairments, mainly attributable to stroke, were assigned to either the experimental or the active control group. In the experimental group a working memory training was combined with a recollection training based on the repetition-lag procedure. Patients in the active control group received the memory therapy usually provided in the rehabilitation center. Both groups received nine hours of therapy. Prior (T0) and subsequent (T1) to the therapy, patients were evaluated on an everyday memory test (EMT) as well as on a neuropsychological test battery. Based on factor analysis of the neuropsychological test scores at T0 we calculated composite scores for working memory, verbal learning and word fluency.

RESULTS

After treatment, the intervention group showed a significantly greater improvement for WM performance compared with the active control group. More importantly, performance on the EMT also improved significantly in patients receiving the recollection and working memory training compared with patients with standard memory training.

CONCLUSION

Our results show that combining working memory and recollection training significantly improves performance on everyday memory tasks, demonstrating far transfer effects. The present study argues in favor of a process-based approach for treating memory impairments. (PsycINFO Database Record

Endovascular therapy versus thrombolysis in patients with large vessel occlusions within the anterior circulation aged ≥80 years

BACKGROUND AND PURPOSE

In patients with large vessel occlusions, endovascular treatment (ET) has been shown to be superior to intravenous thrombolysis (IVT) in recent trials. However, the effectiveness of ET in elderly patients is uncertain.

METHODS

Using our stroke database, we compared the rates of good outcome (modified Rankin scale (mRS) ≤2), excellent outcome (mRS 0-1), poor outcome (mRS 5-6) at discharge, in-hospital death, infarct size, and symptomatic intracranial hemorrhage (SICH) in patients aged ≥80 years with distal intracranial carotid artery, M1 and M2 occlusions during two time periods.

RESULTS

From January 2008 to October 2012, 217 patients were treated with IVT and, from November 2012 to October 2017, 209 patients received ET with stent retrievers (with or without IVT). Significantly more patients in the ET group than in the IVT group had a good outcome (25% vs 16%, P<0.05), as well as an excellent outcome (12% vs 4%, P<0.01). Significantly fewer patients in the ET group than in the IVT group died (14% vs 22%, P<0.05) or had a poor outcome (35% vs 52%, P<001). The SICH rates were lower after ET than after IVT (1% vs 6%, P<0.01), and the infarct sizes were smaller after ET than after IVT.

CONCLUSIONS

Compared with IVT, the routine use of ET significantly improved the early clinical and radiological outcome in patients with anterior circulation large vessel occlusions aged ≥80 years. Nevertheless, poor outcome rates were high so the role of ET needs to be defined further in this population.

Association of Cerebral Amyloid-β Aggregation With Cognitive Functioning in Persons Without Dementia

IMPORTANCE

Cerebral amyloid-β aggregation is an early event in Alzheimer disease (AD). Understanding the association between amyloid aggregation and cognitive manifestation in persons without dementia is important for a better understanding of the course of AD and for the design of prevention trials.

OBJECTIVE

To investigate whether amyloid-β aggregation is associated with cognitive functioning in persons without dementia.

DESIGN, SETTING, AND PARTICIPANTS

This cross-sectional study included 2908 participants with normal cognition and 4133 with mild cognitive impairment (MCI) from 53 studies in the multicenter Amyloid Biomarker Study. Normal cognition was defined as having no cognitive concerns for which medical help was sought and scores within the normal range on cognitive tests. Mild cognitive impairment was diagnosed according to published criteria. Study inclusion began in 2013 and is ongoing. Data analysis was performed in January 2017.

MAIN OUTCOMES AND MEASURES

Global cognitive performance as assessed by the Mini-Mental State Examination (MMSE) and episodic memory performance as assessed by a verbal word learning test. Amyloid aggregation was measured with positron emission tomography or cerebrospinal fluid biomarkers and dichotomized as negative (normal) or positive (abnormal) according to study-specific cutoffs. Generalized estimating equations were used to examine the association between amyloid aggregation and low cognitive scores (MMSE score ≤27 or memory z score≤-1.28) and to assess whether this association was moderated by age, sex, educational level, or apolipoprotein E genotype.

RESULTS

Among 2908 persons with normal cognition (mean [SD] age, 67.4 [12.8] years), amyloid positivity was associated with low memory scores after age 70 years (mean difference in amyloid positive vs negative, 4% [95% CI, 0%-7%] at 72 years and 21% [95% CI, 10%-33%] at 90 years) but was not associated with low MMSE scores (mean difference, 3% [95% CI, -1% to 6%], P = .16). Among 4133 patients with MCI (mean [SD] age, 70.2 [8.5] years), amyloid positivity was associated with low memory (mean difference, 16% [95% CI, 12%-20%], P < .001) and low MMSE (mean difference, 14% [95% CI, 12%-17%], P < .001) scores, and this association decreased with age. Low cognitive scores had limited utility for screening of amyloid positivity in persons with normal cognition and those with MCI. In persons with normal cognition, the age-related increase in low memory score paralleled the age-related increase in amyloid positivity with an intervening period of 10 to 15 years.

CONCLUSIONS AND RELEVANCE

Although low memory scores are an early marker of amyloid positivity, their value as a screening measure for early AD among persons without dementia is limited.

A study on the independence of egocentric and allocentric neglect

Currently there seems to be consensus that visuospatial neglect may involve egocentric and allocentric symptoms. However, the relation between the two is still discussed and models have been proposed based on the high correlation between allocentric and egocentric neglect symptoms. To analyze the relation between these two kinds of symptoms we developed a new paradigm. In contrast to previous paradigms, we varied the extension of the search field and we added centered reference targets to evaluate egocentric effects independent from allocentric effects. Patients with exclusively left-sided neglect (n = 15) and left-sided visual field deficit (VFD) (n = 9) were included. Right brain damaged patients (n = 15) and a healthy control (n = 15) acted as control groups. The results revealed egocentric inattention in VFD patients. Neglect patients suffered from egocentric and allocentric neglect, but we found no interaction between both kinds of impairments in the sense of a monotonous additive or multiplicative increase going from right to left in terms of egocentric and allocentric coordinates. On the contrary, at the outmost left allocentric and egocentric positions, the number of omissions did not increase, unlike in outmost right and centered positions. In conclusion, our experiment shows that egocentric and allocentric neglect can be clearly dissociated in neglect patients and do not interact. Inclusion of neglect patients with a VFD may lead to an artificial interaction between egocentric and allocentric symptoms and this may explain the differences with results of previous studies.

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.

THRIVE score predicts clinical and radiological outcome after endovascular therapy or thrombolysis in patients with anterior circulation stroke in everyday clinical practice

BACKGROUND AND PURPOSE

Based on the data of several trials the Totaled Health Risks in Vascular Events (THRIVE) score has been shown to predict outcome after either intravenous thrombolysis (IVT) or endovascular therapy (ET) in acute stroke patients. It is unknown whether the THRIVE score can also predict outcome in everyday clinical practice. Using our prospectively obtained stroke database the utility of the THRIVE score to predict clinical and radiological outcome in everyday clinical practice was analysed.

METHODS

The relationships between THRIVE and good outcome (modified Rankin Scale ≤ 2 at discharge), poor outcome (modified Rankin Scale 5-6), in-hospital death, symptomatic intracranial haemorrhage (SICH) as well as infarct size were examined in patients with distal intracranial carotid artery, M1 and M2 occlusions after either IVT or ET.

RESULTS

From January 2008 to October 2016 a total of 546 patients were treated with IVT and 492 patients received ET with stent retrievers (with or without IVT). In both treatment groups the THRIVE score predicted clinical outcome (Mantel-Haenszel chi-squared tests for trend P < 0.001 for good outcome, P < 0.001 for poor outcome and P < 0.001 for in-hospital death). In the ET group the THRIVE score remained an independent predictor of outcome after controlling for recanalization. The THRIVE score was associated with the infarct size after IVT or ET, whereas it did not predict SICH rates in either treatment group.

CONCLUSIONS

In everyday clinical practice the THRIVE score strongly predicts clinical outcome and the extent of ischaemia after ET or IVT in patients with anterior circulation large vessel occlusions.

Neuropsychological Testing and Machine Learning Distinguish Alzheimer's Disease from Other Causes for Cognitive Impairment

With promising results in recent treatment trials for Alzheimer’s disease (AD), it becomes increasingly important to distinguish AD at early stages from other causes for cognitive impairment. However, existing diagnostic methods are either invasive (lumbar punctures, PET) or inaccurate Magnetic Resonance Imaging (MRI). This study investigates the potential of neuropsychological testing (NPT) to specifically identify those patients with possible AD among a sample of 158 patients with Mild Cognitive Impairment (MCI) or dementia for various causes. Patients were divided into an early stage and a late stage group according to their Mini Mental State Examination (MMSE) score and labeled as AD or non-AD patients based on a post-mortem validated threshold of the ratio between total tau and beta amyloid in the cerebrospinal fluid (CSF; Total tau/Aβ(1–42) ratio, TB ratio). All patients completed the established Consortium to Establish a Registry for Alzheimer’s Disease—Neuropsychological Assessment Battery (CERAD-NAB) test battery and two additional newly-developed neuropsychological tests (recollection and verbal comprehension) that aimed at carving out specific Alzheimer-typical deficits. Based on these test results, an underlying AD (pathologically increased TB ratio) was predicted with a machine learning algorithm. To this end, the algorithm was trained in each case on all patients except the one to predict (leave-one-out validation). In the total group, 82% of the patients could be correctly identified as AD or non-AD. In the early group with small general cognitive impairment, classification accuracy was increased to 89%. NPT thus seems to be capable of discriminating between AD patients and patients with cognitive impairment due to other neurodegenerative or vascular causes with a high accuracy, and may be used for screening in clinical routine and drug studies, especially in the early course of this disease.

Cross-Sectional and Longitudinal Relationships between Depressive Symptoms and Brain Atrophy in MS Patients

Introduction: Depressive symptoms are a frequent and distressing phenomenon in Multiple Sclerosis (MS) patients. Cross-sectional research links these symptoms to reduced brain gray matter volumes in parts of the prefrontal and temporal lobe as well as subcortical structures like the hippocampus, nucleus caudatus and globus pallidus. Nevertheless, prospective relationships between regional gray matter volume and the course of depressive symptoms are poorly understood.

Methods: Forty-four patients with relapsing–remitting or secondary progressive MS participated in a prospective study with two assessments of depressive symptoms and high-resolution MRI with an inter-test-interval of 17 months. Relationships between baseline gray matter volume and baseline depressive symptoms, as well as prospective associations between the development of atrophy and depression were assessed using voxel-based morphometry (VBM).

Results: Cross-sectional analyses revealed an association between depressive symptoms and gray matter loss in the left temporal lobe. Prospective analysis showed that gray matter losses in the right middle cingulate and middle frontal gyrus at baseline predicted increasing depressive symptoms during follow-up. Increase in depressive symptoms was related to a concomitant increase in atrophy in the left thalamus and right globus pallidus.

Discussion: Our results fit well into the concept of a disturbed cortico–striatal–pallido–thalamic loop in depression. In this framework, progressive gray matter loss in limbic basal ganglia structures including globus pallidus and thalamus may lead to depression-typical deficits in hedonic motivation, whereas atrophy of the prefrontal cortex may contribute to maladaptive coping strategies, promoting an unfavorable development of depressive symptoms.

Counteracting Fatigue in Multiple Sclerosis with Right Parietal Anodal Transcranial Direct Current Stimulation

Background

Fatigue in multiple sclerosis (MS) patients appears to correlate with vigilance decrement as reflected in an increase in reaction time (RT) and errors with prolonged time-on-task.

Objectives

The aim of this study was to investigate whether anodal transcranial direct current stimulation (tDCS) over the right parietal or frontal cortex counteracts fatigue-associated vigilance decrement and subjective fatigue.

Methods

In study I, a randomized double-blind placebo-controlled study, anodal tDCS (1.5 mA) was delivered to the right parietal cortex or the right frontal cortex of 52 healthy participants during the first 20 min of a 40-min lasting visual vigilance task. Study II, also a randomized double-blind placebo-controlled study, investigated the effect of anodal tDCS (1.5 mA) over the right parietal cortex in 46 MS patients experiencing cognitive fatigue. tDCS was delivered for 20 min before patients performed a 20-min lasting visual vigilance task.

Results

Study I showed that right parietal stimulation, but not right frontal stimulation, counteracts the increase in RT associated with vigilance decrement. Hence, only right parietal stimulation was applied to the MS patients in study II. Stimulation had a significant effect on vigilance decrement in mildly to moderately cognitively fatigued MS patients. Vigilance testing significantly increased the feeling of fatigue independent of stimulation.

Conclusion

Anodal tDCS over the right parietal cortex can counteract the increase in RTs during vigilance performance, but not the increase in subjective fatigue. This finding is compatible with our model of fatigue in MS, suggesting a dissociation between the feeling and the behavioral characteristics of fatigue.

The Impact of MS-Related Cognitive Fatigue on Future Brain Parenchymal Loss and Relapse: A 17-Month Follow-up Study

Background

Fatigue is a disabling syndrome in multiple sclerosis (MS), which may be associated with inflammation and faster disease progression.

Objective

To analyze the significance of cognitive fatigue for subsequent disease progression.

Method

We followed 46 MS patients and 14 healthy controls in a study over 17 months. At the beginning (t1) and at the end (t2) of the study participants scored their fatigue, performed the Multiple Sclerosis Functional Composite and received MRI scanning, encompassing MPR T1, FLAIR, and DTI sequences. At t1, MS patients were divided into those with and those without cognitive fatigue (cut-off score for moderate cognitive fatigue of the Fatigue Scale for Motor and Cognition). We calculated ANCOVAs for repeated measurement to analyze the relevance of cognitive fatigue status for the number of relapses and for MRI parameters.

Results

At t1, but not at t2, patients with cognitive fatigue showed increased axial and radial diffusivity of corpus callosum fibers. At t2, these patients showed significantly more loss of brain parenchyma and greater enlargement of lateral ventricles. Moreover, they developed more relapses, but there was no difference in lesion load or in performance deterioration. Additional analyses showed that only cognitive fatigue but not a more general score for fatigue (Fatigue Severity Scale) had an impact on the worsening of the disease status.

Conclusion

Patients with cognitive fatigue may develop more brain atrophy and relapses during the next 17 months than patients without cognitive fatigue. Hence, experiencing cognitive fatigue might indicate more aggressive inflammatory processes and subsequent neurodegeneration.

Evaluating the Impact of an Accountable Care Organization on Population Health: The Quasi-Experimental Design of the German Gesundes Kinzigtal

A central goal of accountable care organizations (ACOs) is to improve the health of their accountable population. No evidence currently links ACO development to improved population health. A major challenge to establishing the evidence base for the impact of ACOs on population health is the absence of a theoretically grounded, robust, operationally feasible, and meaningful research design. The authors present an evaluation study design, provide an empirical example, and discuss considerations for generating the evidence base for ACO implementation. A quasi-experimental study design using propensity score matching in combination with small-scale exact matching is implemented. Outcome indicators based on claims data were constructed and analyzed. Population health is measured by using a range of mortality indicators: mortality ratio, age at time of death, years of potential life lost/gained, and survival time. The application is assessed using longitudinal data from Gesundes Kinzigtal, one of the leading population-based ACOs in Germany. The proposed matching approach resulted in a balanced control of observable differences between the intervention (ACO) and control groups. The mortality indicators used indicate positive results. For example, 635.6 fewer years of potential life lost (2005.8 vs. 2641.4; t-test: sig. P < 0.05*) in the ACO intervention group (n = 5411) attributable to the ACO, also after controlling for a potential (indirect) immortal time bias by excluding the first half year after enrollment from the outcome measurement. This empirical example of the impact of a German ACO on population health can be extended to the evaluation of ACOs and other integrated delivery models of care.

Three Arguments Against Methodological Solipsism as a Research Strategy of Psychology

Contemporary cognitive psychologists share methodological solipsism (MS) as a general research strategy. MS postulates that a complete explanatory level dealing exclusively with processes within an organism is the domain of psychology. The paper undertakes a critical review of MS. By reanalysing the debate between proponents of MS (cf. Fodor & Pylyshyn, 1981) and proponents of ecological realism (cf. Gibson, 1966, 1979), it will be shown that MS is theoretically unsound. As a second step, problems concerning the concept of transduction and invariance detection, using movement perception as a concrete example, are discussed. Existing findings do not support the principle of MS. The third step consists in discussing the status of MS in the theory of problemsolving developed by Newell and Simon (1972). The next section of the paper is devoted to the development of a model that fulfils the conditions stipulated by the critique of the principles of MS. The last part presents a summary of the differences of the developed model in relation to MS.