Memory, attention, and executive function in chronic fatigue syndrome

Phenylephrine alters phase synchronization between cerebral blood velocity and blood pressure in ME/CFS with orthostatic intolerance

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) with orthostatic intolerance (OI) is characterized by neurocognitive deficits perhaps related to upright hypocapnia and loss of cerebral autoregulation (CA). We performed N-back neurocognition testing and calculated the phase synchronization index (PhSI) between arterial pressure (AP) and cerebral blood velocity (CBV) as a time-dependent measurement of cerebral autoregulation in 11 control (mean age = 24.1 yr) and 15 patients with ME/CFS (mean age = 21.8 yr). All patients with ME/CFS had postural tachycardia syndrome (POTS). A 10-min 60° head-up tilt (HUT) significantly increased heart rate (109.4 ± 3.9 vs. 77.2 ± 1.6 beats/min, P < 0.05) and respiratory rate (20.9 ± 1.7 vs. 14.2 ± 1.2 breaths/min, P < 0.05) and decreased end-tidal CO2 (ETCO2; 33.9 ± 1.1 vs. 42.8 ± 1.2 Torr, P < 0.05) in ME/CFS versus control. In ME/CFS, HUT significantly decreased CBV compared with control (-22.5% vs. -8.7%, P < 0.005). To mitigate the orthostatic CBV reduction, we administered supplemental CO2, phenylephrine, and acetazolamide and performed N-back testing supine and during HUT. Only phenylephrine corrected the orthostatic decrease in neurocognition by reverting % correct n = 4 N-back during HUT in ME/CFS similar to control (ME/CFS = 38.5 ± 5.5 vs. ME/CFS + PE= 65.6 ± 5.7 vs. Control 56.9 ± 7.5). HUT in ME/CFS resulted in increased PhSI values indicating decreased CA. Although CO2 and acetazolamide had no effect on PhSI in ME/CFS, phenylephrine caused a significant reduction in PhSI (ME/CFS = 0.80 ± 0.03 vs. ME/CFS + PE= 0.69 ± 0.04, P < 0.05) and improved cerebral autoregulation. Thus, PE improved neurocognitive function in patients with ME/CFS, perhaps related to improved neurovascular coupling, cerebral autoregulation, and maintenance of CBV.NEW & NOTEWORTHY We evaluated cognitive function before and after CO2, acetazolamide, and phenylephrine, which mitigate orthostatic reductions in cerebral blood velocity. Neither CO2 nor acetazolamide affected N-back testing (% correct answers) during an orthostatic challenge. Only phenylephrine improved upright N-back performance in ME/CFS, as it both blocked hyperventilation and increased CO2 significantly compared with those untreated. And only phenylephrine resulted in improved PSI values in both ME/CFS and control while upright, suggesting improved cerebral autoregulation.

Multi-target drugs for the treatment of cognitive impairment and fatigue in post-COVID syndrome: focus on Ginkgo biloba and Rhodiola rosea

Cognitive impairment, depression and (mental) fatigue represent the most frequent neuropsychiatric symptoms of the post-COVID syndrome. Neuroinflammation, oxidative stress and mitochondrial dysfunction have been identified as common pathophysiological mechanisms underlying these symptoms. Attempts to treat post-COVID-associated cognitive impairment and fatigue with different drugs available for other diseases have not yet been successful. One probable explanation could be that these drugs work by one specific mechanism of action only and not in a broad multi-target way. Therefore, they will not address the broad pathophysiological spectrum possibly responsible for cognitive impairment, depression and fatigue in post-COVID syndrome. Notably, nearly all drugs currently under investigation for fatigue in post-COVID syndrome are rather addressing one single target instead of the several pathomechanisms underlying this condition. Contrary to this approach, herbal drugs often consist of many different ingredients with different pharmacological properties and pharmacological targets. Therefore, these drugs might be a promising approach for the treatment of the broad symptomatic presentation and the pathophysiological mechanisms of cognitive impairment and fatigue following a SARS-CoV-2 infection. Of these herbal drugs, extracts of Ginkgo biloba and Rhodiola rosea probably are the best investigated candidates. Their broad pharmacological spectrum in vitro and in vivo includes anti-oxidative, anti-inflammatory, antidepressant as well as properties reducing cognitive impairment and fatigue. In several studies, both drugs showed positive effects on physical and mental fatigue and impaired cognition. Moreover, depressive symptoms were also reduced in some studies. However, even if these results are promising, the data are still preliminary and require additional proof by further studies.

Persistent olfactory learning deficits during and post-COVID-19 infection

Quantifying olfactory impairments can facilitate early detection of Coronavirus disease 2019 (COVID-19). Despite being a debated topic, many reports provide evidence for the neurotropism of SARS-CoV-2. However, a sensitive, specific, and accurate non-invasive method for quantifying persistent neurological impairments is missing to date. To quantify olfactory detectabilities and neurocognitive impairments in symptomatic COVID-19 patients during and post-infection periods, we used a custom-built olfactory-action meter (OAM) providing accurate behavioral readouts. Ten monomolecular odors were used for quantifying olfactory detectabilities and two pairs of odors were employed for olfactory matching tests. We followed cohorts of healthy subjects, symptomatic patients, and recovered subjects for probing olfactory learning deficits, before the Coronavirus Omicron variant was reported in India. Our method identifies severe and persistent olfactory dysfunctions in symptomatic patients during COVID-19 infection. Symptomatic patients and recovered subjects showed significant olfactory learning deficits during and post-infection periods, 4-18 months, in comparison to healthy subjects. On comparing olfactory fitness, we found differential odor detectabilities and olfactory function scores in symptomatic patients and asymptomatic carriers. Our results indicate probable long-term neurocognitive deficits in COVID-19 patients imploring the necessity of long-term tracking during post-infection period. Differential olfactory fitness observed in symptomatic patients and asymptomatic carriers demand probing mechanisms of potentially distinct infection routes.

Impact of fatigue on anaesthesia providers: a scoping review

BACKGROUND

Recently, fatigue has received more attention as a workplace hazard. This scoping review focuses on fatigue in anaesthesia providers. We explore the prevalence of fatigue in anaesthesia providers, and we examine how fatigue impacts their performance.

METHODS

A literature search was independently conducted from December 2019 through March 2020. The following four databases were consulted: MEDLINE, CINAHL, EMBASE, and PubPsych. Only studies discussing fatigue in anaesthesia providers were eligible.

RESULTS

The initial database search identified a total of 118 studies, of which 30 studies were included in the review. Eight articles concerned the prevalence of fatigue in anaesthesia providers, whereas 22 explored the impact of fatigue on the performance of anaesthesia providers. Up to 60.8% of anaesthesia providers suffered from severe excessive daytime sleepiness, and fatigue was denoted as a common workplace problem in up to 73.1% of anaesthesia providers. Fatigue had a negative influence on medication errors and vigilance, and it decreased the performance of anaesthesia providers during laboratory psychomotor testing. There was a decrease in non-technical skills (notably communication and teamwork) and worsening mood when fatigued.

CONCLUSIONS

Based on this scoping review, fatigue is a prevalent a phenomenon that anaesthesia providers cannot ignore. A combination of deterioration in non technical skills, increased medication errors, loss of sustained attention, and psychomotor decline can lead to poorer performance and cause patient harm. Concrete strategies to mitigate fatigue should be developed.

Effects of Low Mental Energy from Long Periods of Work on Brain-Computer Interfaces

Brain-computer interfaces (BCIs) provide novel hands-free interaction strategies. However, the performance of BCIs is affected by the user’s mental energy to some extent. In this study, we aimed to analyze the combined effects of decreased mental energy and lack of sleep on BCI performance and how to reduce these effects. We defined the low-mental-energy (LME) condition as a combined condition of decreased mental energy and lack of sleep. We used a long period of work (>=18 h) to induce the LME condition, and then P300- and SSVEP-based BCI tasks were conducted in LME or normal conditions. Ten subjects were recruited in this study. Each subject participated in the LME- and normal-condition experiments within one week. For the P300-based BCI, we used two decoding algorithms: stepwise linear discriminant (SWLDA) and least square regression (LSR). For the SSVEP-based BCI, we used two decoding algorithms: canonical correlation analysis (CCA) and filter bank canonical correlation analysis (FBCCA). Accuracy and information transfer rate (ITR) were used as performance metrics. The experimental results showed that for the P300-based BCI, the average accuracy was reduced by approximately 35% (with a SWLDA classifier) and approximately 40% (with a LSR classifier); the average ITR was reduced by approximately 6 bits/min (with a SWLDA classifier) and approximately 7 bits/min (with an LSR classifier). For the SSVEP-based BCI, the average accuracy was reduced by approximately 40% (with a CCA classifier) and approximately 40% (with a FBCCA classifier); the average ITR was reduced by approximately 20 bits/min (with a CCA classifier) and approximately 19 bits/min (with a FBCCA classifier). Additionally, the amplitude and signal-to-noise ratio of the evoked electroencephalogram signals were lower in the LME condition, while the degree of fatigue and the task load of each subject were higher. Further experiments suggested that increasing stimulus size, flash duration, and flash number could improve BCI performance in LME conditions to some extent. Our experiments showed that the LME condition reduced BCI performance, the effects of LME on BCI did not rely on specific BCI types and specific decoding algorithms, and optimizing BCI parameters (e.g., stimulus size) can reduce these effects.

Systematic review and meta-analysis of cognitive impairment in myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS)

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is commonly associated with cognitive complaints. To bring out the neuropsychological symptomatology inherent to ME/CFS, we conducted a systematic review according to PRISMA and MOOSE guidelines of the literature through the analysis of 764 studies published between 1988 and 2019 by using PubMed Central website and Clarivate analytics platform. We performed a meta-analysis to delineate an idea of the neuropsychological profile inherent in ME/CFS. The clinical picture typically affects visuo-spatial immediate memory (g = - 0.55, p = 0.007), reading speed (g = - 0.82, p = 0.0001) and graphics gesture (g = - 0.59, p = 0.0001). Analysis also revealed difficulties in several processes inherent in episodic verbal memory (storage, retrieval, recognition) and visual memory (recovery) and a low efficiency in attentional abilities. Executive functions seemed to be little or not affected and instrumental functions appeared constantly preserved. With regard to the complexity and heterogeneity of the cognitive phenotype, it turns out that determining a sound clinical picture of ME/CFS cognitive profile must go through a neuropsychological examination allowing a complete evaluation integrating the notion of agreement between the choice and the number of tests and the complexity intrinsic to the pathology.

Differences in fatigue-like behavior in the lipopolysaccharide and poly I:C inflammatory animal models

Central fatigue is a condition associated with impairment of the central nervous system often leading to the manifestation of a range of debilitating symptoms. Fatigue can be a consequence of systemic inflammation following an infection. Administration of lipopolysaccharide (LPS) and polyriboinosinic:polyribocytidlic (poly I:C) to animals can induce systemic inflammation by mimicking a bacterial or viral infection respectively and therefore have been used as models of fatigue. We evaluated a range of phenotypic behaviors exhibited in the LPS and poly I:C animal models to assess whether they adequately replicate fatigue symptomology in humans. In addition to standard observation- and intervention-based behavioral assessments, we used powerful in-cage monitoring technology to quantify rodent behavior without external interference. LPS and poly I:C treated Sprague Dawley rats displayed 'sickness behaviors' of elevated temperature, weight loss and reduced activity in the open field test and with in-cage monitoring within 24 h post-treatment, but only LPS-treated rats displayed these behaviors beyond these acute timepoints. Once sickness behavior diminished, LPS-treated rats exhibited an increase in reward-seeking and motivation behaviors. Overall, these results suggest that the LPS animal model produces an extensive and sustained fatigue-like phenotype, whereas the poly I:C model only produced acute effects. Our results suggest that the LPS animal model is a more suitable candidate for further studies on central fatigue-like behavior.

Apolipoprotein E Polymorphism and Frailty: Apolipoprotein ε4 Allele Is Associated with Fatigue but Not Frailty Syndrome in a Community-Dwelling Older Population Cohort

OBJECTIVE

Frailty is known to be influenced by genetics, however, little evidence on the association of Apolipoprotein E (ApoE) genotype and frailty exists which we aim to investigate.

DESIGN

This study is a cross-sectional analysis from a prospective longitudinal study cohort.

SETTING AND PARTICIPANTS

Community-dwelling individuals aged 55 years and older from Beijing region in China.

MEASUREMENTS

A total of 3,569 older adults with a mean age of 75.06(±6.79) years were included. We investigated the association between ApoE polymorphism and frailty syndrome using the frailty index (FI) and frailty phenotype (including association with individual components of the frailty phenotype). Logistic regressions were performed to investigate the relation between ApoE variants and frailty.

RESULTS

There was no significant association between ApoE variants and frailty as assessed by the FI. In the age and sex-adjusted model, compared to the ApoE e3/e3 carriers ApoE e4 carriers had almost 1.5 times higher odds of being frail as assessed by the frailty phenotype. However, the significance was lost on the model with adjustment for cognitive impairment. Compared to the ApoE e3/e3 carriers ApoE e4 carriers had almost two times higher odds of fatigue. ApoE e4 heterozygotes had higher odds of fatigue compared to ApoE e4 non-carriers. No significant association was found between ApoE variants and other components of frailty phenotype.

CONCLUSIONS

Our findings do not support an association between ApoE genotype and frailty irrespective of the frailty assessment tools. Fatigue in older adults is the only component of frailty phenotype influenced by ApoE genotype.

Physical Frailty Phenotype Criteria and Their Synergistic Association on Cognitive Functioning

BACKGROUND

Frailty (physical frailty phenotype [PFP]) and its criteria (slow gait, weakness, weight loss, low activity, and exhaustion) are each associated with cognitive dysfunction. The extent to which the PFP is associated with cognition beyond that expected from its component parts remains uncertain.

METHOD

We used the National Health and Aging Trends Study to quantify associations between PFP criteria and cognitive performance (level/change) using adjusted mixed effects models. We tested whether frailty was associated with excess cognitive vulnerability (synergistic/excess effects, Cohen's d) beyond criteria contributions by assessing interactions between each criterion and frailty.

RESULTS

Among 7439 community-dwelling older adults (mean age = 75.2 years) followed for a mean of 3.2 years (SE = 0.03), 14.1% were frail. The PFP and PFP criteria were all associated with lower baseline cognitive performance, among which slow gait (-0.31 SD, SE = 0.02) and frailty (-0.23 SD, SE = 0.02) were strongest. Only slow gait (-0.03 SD/year, SE = 0.01), frailty (-0.02 SD/year, SE = 0.01), weight loss (-0.02 SD/year, SE = 0.01), and weakness (-0.02 SD/year, SE = 0.01) were associated with cognitive decline. Frailty was associated with cognitive performance above and beyond each criterion (excess effects ranging from -0.07 SD [SE = -0.05] for slow gait to -0.23 SD [SE = 0.03] for weakness); the same was not true for cognitive decline. Slow gait was the only criterion associated with cognitive change among both frail and nonfrail participants (frail: Cohen's d/year = -0.03, SE = 0.01; nonfrail: Cohen's d/year = -0.02, SE = 0.01).

CONCLUSIONS

PFP is an important frailty measure that is cross-sectionally associated with lower cognitive performance, but not with subsequent cognitive decline, above and beyond its criteria contributions. Further research into the construct of frailty as a "syndrome" correlated with cognition and other adverse outcomes is needed.

Fatigue and recovery among Malaysian doctors: the role of work-related activities during non-work time

OBJECTIVES

This paper aims to estimate the level of acute fatigue, chronic fatigue and intershift recovery among doctors working at public hospitals in Malaysia and determine their inter-relationship and their association with work-related activities during non-work time.

DESIGN

Cross-sectional.

SETTING

Seven core clinical disciplines from seven tertiary public hospitals in Malaysia.

PARTICIPANTS

Study was conducted among 330 randomly-sampled doctors. Response rate was 80.61% (n=266).

RESULTS

The mean score of acute fatigue, chronic fatigue and intershift recovery were 68.51 (SD=16.549), 54.60 (SD=21.259) and 37.29 (SD=19.540), respectively. All these scores were out of 100 points each. Acute and chronic fatigue were correlated (r=0.663), and both were negatively correlated with intershift recovery (r=-0.704 and r=-0.670, respectively). Among the work-related activities done during non-work time, work-related ruminations dominated both the more frequent activities and the association with poorer fatigue and recovery outcomes. Rumination on being scolded/violated was found to be positively associated with both acute fatigue (adjusted regression coefficient (Adj.b)=2.190, 95% CI=1.139 to 3.240) and chronic fatigue (Adj.b=5.089, 95% CI=3.876 to 6.303), and negatively associated with recovery (Adj.b=-3.316, 95% CI=-4.516 to -2.117). Doing work task at workplace or attending extra work-related activities such as locum and attending training were found to have negative associations with fatigue and positive associations with recovery. Nevertheless, doing work-related activities at home was positively associated with acute fatigue. In terms of communication, it was found that face-to-face conversation with partner did associate with higher recovery but virtual conversation with partner associated with higher acute fatigue and lower recovery.

CONCLUSIONS

Work-related ruminations during non-work time were common and associated with poor fatigue and recovery outcomes while overt work activities done at workplace during non-work time were associated with better fatigue and recovery levels. There is a need for future studies with design that allow causal inference to address these relationships.

Impacts of trait anxiety on visual working memory, as a function of task demand and situational stress

Higher trait anxiety can impair cognitive functioning via attention, but relatively little is known about the impacts on visual working memory. These were investigated using previously validated visual feature binding tasks. In Study 1, participants' memory for visual features (shapes) and feature bindings (coloured shapes) was assessed. Stimulus presentation was simultaneous or sequential, varying attentional demand, and participants were grouped according to trait cognitive anxiety (low, moderate, high). No reliable effect of trait anxiety, either cognitive or somatic, was found on memory accuracy, but moderate trait cognitive anxiety was associated with faster correct response times (i.e. increased efficiency) when stimuli were sequentially presented. In Study 2, the role of situational stress was explored during a simultaneously presented task. Higher trait cognitive and somatic anxiety were both associated with poorer efficiency during both shape and binding memory tasks. Trait somatic anxiety also predicted poorer binding effectiveness (i.e. accuracy), in those reporting higher state cognitive anxiety. Situational stress predicted binding effectiveness, but never interacted with trait anxiety, and was therefore not necessary to observe these trait anxiety-visual working memory relationships. Trait cognitive and somatic anxiety, and situational stress, therefore each influence visual working memory performance.

The Association Between Work-Related Rumination and Executive Function Using the Behavior Rating Inventory of Executive Function

Work-related rumination has been associated with a number of health complaints, however, little is known about the underlying factors associated with rumination. Previous work using proxy measures of executive function showed work-related rumination to be negatively associated with executive function. In this paper, we report two studies that examined the association between work-related rumination and executive function utilizing an ecological valid measure of executive function: the Behavior Rating Inventory of Executive Function (BRIEF-A, Roth et al., 2005). In study 1 (N = 63), high, relative to low work-related ruminators, were found to demonstrate lower executive function skills, in eight of the nine subscales of the BRIEF. The aim of study 2 (N = 237) was to identify, the key executive function subscale/s associated with work-related rumination. Controlling for known factors associated with work-related rumination (fatigue and sleep), regression analysis identified the behavioral regulation subscale “shift” as the key predictor within the model. Shift relates to our ability to switch attention, to think about different solutions, and dealing with and accepting change. It was concluded that these findings lend support for future research to develop interventions for enhancing shift ability, as an aid to reduce work-related ruminative thinking.

The Impact of a Structured Exercise Programme upon Cognitive Function in Chronic Fatigue Syndrome Patients

BACKGROUND

Cognitive function disturbance is a frequently described symptom of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). In this study, the effects of a structured exercise programme (SEP) upon cognitive function in ME/CFS patients was examined.

METHODS

Out of the 53 ME/CFS patients initiating SEP 34 (64%) completed the 16 week programme. Cognitive function was assessed using a computerized battery test consisting of a Simple Reaction Time (SRT) (repeated three times) and Choice Reaction Time (CRT) measurements, a Visual Attention Test (VAT) and a Delayed Matching to Sample (DMS) assessment.

RESULTS

Statistically significant improvement was noted in the third attempt to SRT in reaction time for correct answers, p = 0.045, r = 0.24. Moreover, significant improvement was noted in VAT reaction time, number of correct answers and errors committed, p = 0.02, omega = 0.03, p = 0.007, r = 0.34 and p = 0.004, r = 0.35, respectively. Non-significant changes were noted in other cognitive tests.

CONCLUSIONS

A substantial number of participants were unwilling or unable to complete the exercise programme. ME/CFS patients able to complete the SEP showed improved visual attention both in terms of reaction time and correctness of responses and processing speed of simple visual stimuli.

A unifying theory for cognitive abnormalities in functional neurological disorders, fibromyalgia and chronic fatigue syndrome: systematic review

BACKGROUND

Functional cognitive disorder (FCD) describes cognitive dysfunction in the absence of an organic cause. It is increasingly prevalent in healthcare settings yet its key neuropsychological features have not been reported in large patient cohorts. We hypothesised that cognitive profiles in fibromyalgia (FM), chronic fatigue syndrome (CFS) and functional neurological disorders (FNDs) would provide a template for characterising FCD.

METHODS

We conducted a systematic review of studies with cognition-related outcomes in FM, CFS and FND.

RESULTS

We selected 52 studies on FM, 95 on CFS and 39 on FND. We found a general discordance between high rates of subjective cognitive symptoms, including forgetfulness, distractibility and word-finding difficulties, and inconsistent objective neuropsychological deficits. Objective deficits were reported, including poor selective and divided attention, slow information processing and vulnerability to distraction. In some studies, cognitive performance was inversely correlated with pain, exertion and fatigue. Performance validity testing demonstrated poor effort in only a minority of subjects, and patients with CFS showed a heightened perception of effort.

DISCUSSION

The cognitive profiles of FM, CFS and non-cognitive FND are similar to the proposed features of FCD, suggesting common mechanistic underpinnings. Similar findings have been reported in patients with mild traumatic brain injury and whiplash. We hypothesise that pain, fatigue and excessive interoceptive monitoring produce a decrease in externally directed attention. This increases susceptibility to distraction and slows information processing, interfering with cognitive function, in particular multitasking. Routine cognitive processes are experienced as unduly effortful. This may reflect a switch from an automatic to a less efficient controlled or explicit cognitive mode, a mechanism that has also been proposed for impaired motor control in FND. These experiences might then be overinterpreted due to memory perfectionism and heightened self-monitoring of cognitive performance.

Functional MRI on executive functioning in aging and dementia: A scoping review of cognitive tasks

Cognitive decline with aging and dementia is especially poignant with regard to the executive functioning that is necessary for activities of daily independent living. The relationship between age-related neurodegeneration in the prefrontal cortex and executive functioning has been uniquely investigated using task-phase functional magnetic resonance imaging (fMRI) to detect brain activity in response to stimuli; however, a comprehensive list of task designs that have been implemented to task-phase fMRI is absent in the literature. The purpose of this review was to recognize what methods have been used to study executive functions with aging and dementia in fMRI tasks, and to describe and categorize them. The following cognitive subdomains were emphasized: cognitive flexibility, planning and decision-making, working memory, cognitive control/inhibition, semantic processing, attention and concentration, emotional functioning, and multitasking. Over 30 different task-phase fMRI designs were found to have been implemented in the literature, all adopted from standard neuropsychological assessments. Cognitive set-shifting and decision-making tasks were particularly well studied in regard to age-related neurodegeneration, while emotional functioning and multitasking designs were found to be the least utilized. Summarizing the information on which tasks have shown the greatest usability will assist in the future design and implementation of effective fMRI experiments targeting executive functioning.

Cortical hypoactivation during resting EEG suggests central nervous system pathology in patients with chronic fatigue syndrome

We investigated central fatigue in 50 patients with chronic fatigue syndrome (CFS) and 50 matched healthy controls (HC). Resting state EEG was collected from 19 scalp locations during a 3 min, eyes-closed condition. Current densities were localized using exact low-resolution electromagnetic tomography (eLORETA). The Multidimensional Fatigue Inventory (MFI-20) and the Fatigue Severity Scale (FSS) were administered to all participants. Independent t-tests and linear regression analyses were used to evaluate group differences in current densities, followed by statistical non-parametric mapping (SnPM) correction procedures. Significant differences were found in the delta (1-3 Hz) and beta-2 (19-21 Hz) frequency bands. Delta sources were found predominately in the frontal lobe, while beta-2 sources were found in the medial and superior parietal lobe. Left-lateralized, frontal delta sources were associated with a clinical reduction in motivation. The implications of abnormal cortical sources in patients with CFS are discussed.

Are probiotic treatments useful on fibromyalgia syndrome or chronic fatigue syndrome patients? A systematic review

Evidence suggests that the gut microbiota might play an important role in fibromyalgia syndrome (FMS) and chronic fatigue syndrome (CFS). Our goal is to systematically review the reported effect of probiotic treatments in patients diagnosed with FMS or CFS. A systematic review was carried out using 14 databases (PubMed, Cochrane Library, Scopus, PsycINFO, and others) in February 2016 to search for randomised controlled trials (RCTs) and pilot studies of CFS or FMS patient, published in the last ten years (from 2006 to 2016). The Jadad scale was used to asseverate the quality of the clinical trials considered. Two studies (n=83) met the inclusion criteria, which were performed in CFS patients and both studies were considered as a 'High range of quality score'. The administration of Lactobacillus casei strain Shirota in CFS patients, over the course of 8 weeks, reduced anxiety scores. Likewise, this probiotic changed the faecal composition following 8 weeks of treatment. Additionally, the treatment with Bifidobacterium infantis 35624 in CFS patients, during the same period, reduced inflammatory biomarkers. The evidence about the usefulness of probiotics in CFS and FMS patients remains limited. The studied strains of probiotics have demonstrated a significant effect on modulating the anxiety and inflammatory processes in CFS patients. However, more experimental research, focusing mainly on the symptoms of the pathologies studied, is needed.

Executive function and quality of life in individuals with Marfan syndrome

PURPOSE

Marfan syndrome (MFS) is a connective tissue disorder that affects skeletal, ocular, pulmonary, cardiovascular, and central nervous systems. Psychological and physiologic symptoms may lead to diminished quality of life (QoL) in individuals with MFS compared with healthy individuals. Currently, there is little evidence regarding the impact of MFS on executive function and QoL. This study examined perceptions of executive function and QoL among persons with MFS.

METHOD

A total of 318 participants with MFS completed surveys assessing perceptions of executive function abilities and QoL. Responses to executive function questions were grouped using principle component analysis. Responses to QoL questions were separated into overall QoL, questions dealing with satisfaction of QoL, and importance placed on aspect of QoL.

RESULTS

Principle component analysis revealed that executive function difficulties, particularly mental fatigue, associated with MFS symptoms affect QoL satisfaction and total QoL. Interestingly, medication status did not significantly impact QoL, over and above executive function difficulties.

CONCLUSIONS

The findings of the current study suggest that individuals with MFS may experience specific executive function difficulties which impact QoL. These findings also have implications for clinicians who work with individuals with MFS.

Cognitive performance change of pediatric patients after conducting frontal transcortical approach to treat lateral ventricular tumor

OBJECTIVE

Applying frontal transcortical approach to treat lateral ventricular tumor is one of the most common neurosurgical manipulations. The frontal transcortical approach generally passes through the middle frontal gyrus in which there is no major function involved in the traditional sense. However, current researches have suggested that the prefrontal cortex (PFC) plays a central role in the whole network of the brain cognitive frame. In addition, cognitive function is crucial in growing and developmental stages and essential for the educational achievement, especially for children. Based on this, the authors in this study analyzed cognitive performance change of pediatric patients who had accepted frontal transcortical operation in 1-year follow-up and discussed the possibility of higher cognitive functions of the damaged region.

PATIENTS AND METHODS

In this single-center study, 15 pediatric patients (median age at surgery, 9.21 years old; range, 6.42-14.17 years old) who had been treated with frontal transcortical approach for lateral ventricular tumors were selected as research objects. The cognitive function assessment was conducting by adopting the revised Wechsler Intelligence Scale for Children-fourth edition (WISC-IV). In addition, the resting-state functional magnetic resonance imaging (resting-state fMRI) and diffusion tensor imaging (DTI) were carried out to measure the level of co-activation and to explore the functional connectivity between the brain regions at the preoperative period and 1-year follow-up after surgery.

RESULTS

GTR was achieved in all patients, and all patients were in good condition after surgery. Compared to the preoperative indices of WISC-IV, patients generally had a lower level of indices of the WISC-IV after surgery, for example, the total IQ was declined to M = 83.60, SD = 9.500 from M = 95.33, SD = 13.844 within 1 year convalescence. The data of perceptual reasoning (t = - 2.392, p = 0.016), processing speed (t = - 2.121, p = 0.033), and total IQ (t = -2.638, p = 0.008) before and after surgery showed statistically significance. Furthermore, decreased functional connectivity and disconnected neural fasciculus were revealed by the size of activation regions in the resting-state fMRI and the reconstruction of three-dimensional images of white matter tracts in the DTI pre- and post-operative.

CONCLUSION

The PFC was not regarded as a major functional area in the past, but the researches at present have shown that the interactions between PFC and other posterior brain regions serve as the basis of the higher cognitive functions. According to imaging manifestations and WISC-IV tasks in this paper, we found that the PFC injury caused by the frontal transcortical approach led to damaged brain structure and impaired the performance of cognitive function. On this basis, we detected that the perceptual reasoning and processing speed maybe have more extensive connections with the middle frontal gyrus.

Effect of load carriage and natural terrain conditions on cognitive performance in desert environments

BACKGROUND

Correct decision making is a critical component of cognitive performance of a soldier, which may be influenced by the load carriage and terrain conditions during their deployment in desert environment.

PURPOSE

The present study was aimed to investigate the effects of loads and terrain conditions on the cognitive performance in a group of twelve healthy heat acclimatized infantry soldiers under natural desert environment.

METHODS

The soldiers participated in a 10min walking trial during carrying no load and also carrying 10.7, 21.4 and 30kg at two terrain conditions viz., sandy and hard. We studied attention, memory and executive function, which are having immense functional importance in military operations. Standardized cognitive test battery was applied to the participants after carrying each magnitude of load at each terrain. Baseline cognitive performance was recorded on a separate day and was compared with the performances recorded after the load carriage trials. An attempt was made to reveal the relationship between physiological workload (relative workload) and cognitive performance at the point of completion of load carriage trials.

RESULTS

Load, terrains and load×terrain interaction did not produce any significant effect (p>0.05) on the cognitive performance. Attention and relative workload were found significantly correlated at hard terrain under no load, 21.4kg and 30kg. Significant correlation was found between executive function and relative workload at hard terrain under no load.

CONCLUSION

Carrying upto 30kg load for 10min at 3.5-4kmph walking speed resulted in improvement in attention at sandy terrain, decrement in memory at both sandy and hard terrains and improvement in executive function at sandy terrain.

The Toronto Hospital Alertness Test scale: relationship to daytime sleepiness, fatigue, and symptoms of depression and anxiety

OBJECTIVE

The Toronto Hospital Alertness Test (THAT) scale was designed to measure alertness, defined as the capacity of the mind to respond appropriately to external and internal stimuli. The present study's aim is to determine normative values of alertness on the THAT and to explore the relationship among excessive daytime sleepiness, fatigue, depressive symptoms, and alertness.

METHODS

Normative data were collected from 60 healthy males and females. To explore the relationship among alertness, daytime sleepiness, fatigue, depression, and anxiety, data were collected from charts of sleep clinic patients. All study subjects completed measures for fatigue, sleepiness, depressive symptoms, and anxiety.

RESULTS

The average score on the THAT was 34.9±7.2 (range 22-50) for the control group. The cutoff score for the THAT, indicative of clinically significant reduced alertness, was determined to be ≤20.5 (mean -2 SD). THAT alertness scores were found to be modestly, significantly, and negatively correlated with fatigue levels (r=-0.39, P<0.001), depressive symptoms (r=-0.53, P<0.001), and anxiety symptoms (r=-0.41, P<0.001). No correlations were found between alertness levels and daytime sleepiness. Regression analyses revealed a significant model (F=19.9, P<0.001, adjusted R (2)=0.35) with depressive symptoms (P<0.001) and fatigue (P=0.006) emerging as the only significant predictors of scores on the THAT.

CONCLUSION

The findings of this study support that sleepiness is not the same as poor alertness. Depressive symptoms and fatigue, but not sleepiness, were found to have a strong and significant impact on levels of alertness. This is the first study to link poor alertness to depressive symptoms.

Neuroprotective mechanism of losartan and its interaction with nimesulide against chronic fatigue stress

Potential role of angiotensin-II and cyclooxygenase have been suggested in the pathophysiology of chronic fatigue stress. The present study has been designed to evaluate the neuroprotective effect of losartan and its interaction with nimesulide against chronic fatigue stress and related complications in mice. In the present study, male Laca mice (20-30 g) were subjected to running wheel activity test session (RWATS) for 6 min daily for 21 days. Losartan, nimesulide and their combinations were administered daily for 21 days, 45 min before being subjected to RWATS. Various behavioral and biochemical and neuroinflammatory mediators were assessed subsequently. 21 days RWATS treatment significantly decreased number of wheel rotations/6 min indicating fatigue stress like behaviors as compared to naive group. 21 days treatment with losartan (10 and 20 mg/kg, ip), nimesulide (5 and 10 mg/kg, po) and their combinations significantly improved behavior [increased number of wheel rotations, reversal of post-exercise fatigue, locomotor activity, antianxiety-like behavior (number of entries, latency to enter and time spent in mirror chamber), and memory performance (transfer latency in plus-maze performance task)], biochemical parameters (reduced serum corticosterone, brain lipid peroxidation, nitrite concentration, acetylcholinesterase activity, restored reduced glutathione levels and catalase activity) as compared to RWATS control. Besides, TNF-α, CRP levels were significantly attenuated by these drugs and their combinations as compared to control. The present study highlights the role of cyclooxygenase modulation in the neuroprotective effect of losartan against chronic fatigue stress-induced behavioral, biochemical and cellular alterations in mice.

Working Memory and Response Inhibition in Patients With Bipolar I Disorder During Euthymic Period

Background:

Several cognitive domains, including attention, memory, and executive functions are impaired in bipolar disorder.

Objectives:

This study aimed to investigate two executive functions (working memory and response inhibition) in patients with bipolar I disorder during remission of the symptoms.

Patients and Methods:

In this case-control design, 30 bipolar I patients (18 to 45 years old) were matched with 30 ones in the control group in terms of age, gender, and education. The patients were selected from Roozbeh Psychiatric Hospital (a hospital affiliated to Tehran University of Medical Sciences) from May to October 2013. They were evaluated and contrasted using working memory (Spatial Span and Spatial Working Memory (SSP and SWM)) and response inhibition (Stop Signal Task (SST)) tests.

Results:

We used independent t-tests for comparing and contrasting 2 groups on total and sub-scales scores of these 3 tests. In terms of SWM test there was a significant difference in between-group error between the two groups (P = 0.05); there was also a meaningful difference between the strategies used by two groups (P = 0.05). In SSP test, a significant difference appeared between averages of span length of the two groups. In the first and last item delays, there was also a clear difference, but the total error index was not noticeably different. In SST test, the direction error indicator in start-stop trials indicated a major difference, while in successful stops ratio, the case group had a lower ratio. In addition, reaction time to stop signs in bipolar group was meaningfully lower than the control group.

Conclusion:

In conclusion, even during remission phase, executive dysfunction is detectable at least in some areas in patients with bipolar disorder.

Phenylephrine alteration of cerebral blood flow during orthostasis: effect on n-back performance in chronic fatigue syndrome

Chronic fatigue syndrome (CFS) with orthostatic intolerance is characterized by neurocognitive deficits and impaired working memory, concentration, and information processing. In CFS, upright tilting [head-up tilt (HUT)] caused decreased cerebral blood flow velocity (CBFv) related to hyperventilation/hypocapnia and impaired cerebral autoregulation; increasing orthostatic stress resulted in decreased neurocognition. We loaded the baroreflex with phenylephrine to prevent hyperventilation and performed n-back neurocognition testing in 11 control subjects and 15 CFS patients. HUT caused a significant increase in heart rate (109.4 ± 3.9 vs. 77.2 ± 1.6 beats/min, P < 0.05) and respiratory rate (20.9 ± 1.7 vs. 14.2 ± 1.2 breaths/min, P < 0.05) and decrease in end-tidal CO2 (ETCO2; 42.8 ± 1.2 vs. 33.9 ± 1.1 Torr, P < 0.05) in CFS vs. control. HUT caused CBFv to decrease 8.7% in control subjects but fell 22.5% in CFS. In CFS, phenylephrine prevented the HUT-induced hyperventilation/hypocapnia and the significant drop in CBFv with HUT (-8.1% vs. -22.5% untreated). There was no difference in control subject n-back normalized response time (nRT) comparing supine to HUT (106.1 ± 6.9 vs. 97.6 ± 7.1 ms at n = 4), and no difference comparing control to CFS while supine (97.1 ± 7.1 vs 96.5 ± 3.9 ms at n = 4). However, HUT of CFS subjects caused a significant increase in nRT (148.0 ± 9.3 vs. 96.4 ± 6.0 ms at n = 4) compared with supine. Phenylephrine significantly reduced the HUT-induced increase in nRT in CFS to levels similar to supine (114.6 ± 7.1 vs. 114.6 ± 9.3 ms at n = 4). Compared with control subjects, CFS subjects are more sensitive both to orthostatic challenge and to baroreflex/chemoreflex-mediated interventions. Increasing blood pressure with phenylephrine can alter CBFv. In CFS subjects, mitigation of the HUT-induced CBFv decrease with phenylephrine has a beneficial effect on n-back outcome.

Induction of interleukin-1β by activated microglia is a prerequisite for immunologically induced fatigue

We previously reported that an intraperitoneal (i.p.) injection of synthetic double-stranded RNA, polyriboinosinic:polyribocytidylic acid (poly-I:C), produced prolonged fatigue in rats, which might serve as a model for chronic fatigue syndrome. The poly-I:C-induced fatigue was associated with serotonin transporter (5-HTT) overexpression in the prefrontal cortex (PFC), a brain region that has been suggested to be critical for fatigue sensation. In the present study, we demonstrated that microglial activation in the PFC was important for poly-I:C-induced fatigue in rats, as pretreatment with minocycline, an inhibitor of microglial activation, prevented the decrease in running wheel activity. Poly-I:C injection increased the microglial interleukin (IL)-1β expression in the PFC. An intracerebroventricular (i.c.v.) injection of IL-1β neutralising antibody limited the poly-I:C-induced decrease in activity, whereas IL-1β (i.c.v.) reduced the activity in a dose-dependent manner. 5-HTT expression was enhanced by IL-1β in primary cultured astrocytes but not in microglia. Poly-I:C injection (i.p.) caused an increase in 5-HTT expression in astrocytes in the PFC of the rat, which was inhibited by pretreatment with minocycline (i.p.) and rat recombinant IL-1 receptor antagonist (i.c.v.). Poly-I:C injection (i.p.) led to a breakdown of the blood-brain barrier and enhanced Toll-like receptor 3 signaling in the brain. Furthermore, direct application of poly-I:C enhanced IL-1β expression in primary microglia. We therefore propose that poly-I:C-induced microglial activation, which may be at least partly caused by a direct action of poly-I:C, enhances IL-1β expression. Then, IL-1β induces 5-HTT expression in astrocytes, resulting in the immunologically induced fatigue.

Association between cognitive performance, physical fitness, and physical activity level in women with chronic fatigue syndrome

Limited scientific evidence suggests that physical activity is directly related to cognitive performance in patients with chronic fatigue syndrome (CFS). To date, no other study has examined the direct relationship between cognitive performance and physical fitness in these patients. This study examined whether cognitive performance and physical fitness are associated in female patients with CFS and investigated the association between cognitive performance and physical activity level (PAL) in the same study sample. We hypothesized that patients who performed better on cognitive tasks would show increased PALs and better performance on physical tests. The study included 31 women with CFS and 13 healthy inactive women. Participants first completed three cognitive tests. Afterward, they undertook a test to determine their maximal handgrip strength, performed a bicycle ergometer test, and were provided with an activity monitor. In patients with CFS, lower peak oxygen uptake and peak heart rate were associated with slower psychomotor speed (p < 0.05). Maximal handgrip strength was correlated with working memory performance (p < 0.05). Both choice and simple reaction time were lower in patients with CFS relative to healthy controls (p < 0.05 and p < 0.001, respectively). In conclusion, physical fitness, but not PAL, is associated with cognitive performance in female patients with CFS.

Cognitive impairments associated with CFS and POTS

Chronic fatigue syndrome (CFS) is characterized by fatigue, sleep dysfunction, and cognitive deficits (Fukuda et al., 1994). Research surrounding cognitive functioning among patients with CFS has found difficulty with memory, attention, and information processing. A similar disorder, postural tachycardia syndrome (POTS), is characterized by increased heart rate, fatigue, and mental cloudiness (Raj et al., 2009). Potential implications of cognitive deficits for patients with CFS and/or POTS are discussed, including difficulties with school and/or employment. A few biological theories (i.e., kindling, impairments in the central nervous system, and difficulty with blood flow) have emerged as potential explanations for the cognitive deficits reported in both CFS and POTS Future research should continue to examine possible explanations for cognitive impairments in CFS and POTS, and ultimately use this information to try and reduce cognitive impairments for these patients.

Caught in the thickness of brain fog: exploring the cognitive symptoms of Chronic Fatigue Syndrome

Chronic Fatigue Syndrome (CFS) is defined as greater than 6 months of persistent fatigue that is experienced physically and cognitively. The cognitive symptoms are generally thought to be a mild cognitive impairment, but individuals with CFS subjectively describe them as "brain fog." The impairment is not fully understood and often is described as slow thinking, difficulty focusing, confusion, lack of concentration, forgetfulness, or a haziness in thought processes. Causes of "brain fog" and mild cognitive impairment have been investigated. Possible physiological correlates may be due to the effects of chronic orthostatic intolerance (OI) in the form of the Postural Tachycardia Syndrome (POTS) and decreases in cerebral blood flow (CBF). In addition, fMRI studies suggest that individuals with CFS may require increased cortical and subcortical brain activation to complete difficult mental tasks. Furthermore, neurocognitive testing in CFS has demonstrated deficits in speed and efficiency of information processing, attention, concentration, and working memory. The cognitive impairments are then perceived as an exaggerated mental fatigue. As a whole, this is experienced by those with CFS as "brain fog" and may be viewed as the interaction of physiological, cognitive, and perceptual factors. Thus, the cognitive symptoms of CFS may be due to altered CBF activation and regulation that are exacerbated by a stressor, such as orthostasis or a difficult mental task, resulting in the decreased ability to readily process information, which is then perceived as fatiguing and experienced as "brain fog." Future research looks to further explore these interactions, how they produce cognitive impairments, and explain the perception of "brain fog" from a mechanistic standpoint.

Could cadmium be responsible for some of the neurological signs and symptoms of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

According to the World Health Organization, Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a neurological disease characterized by widespread inflammation and multi-systemic neuropathology. Aetiology and pathogenesis are unknown, and several agents have been proposed as causative agents or as factors perpetuating the syndrome. Exposure to heavy metals, with particular reference to mercury and gold in dental amalgams, has been considered among the triggers of ME/CFS. Here we hypothesize that cadmium, a widespread occupational and environmental heavy metal pollutant, might be associated with some of the neurological findings described in ME/CFS. In fact, ME/CFS patients show a decrease of the volume of the gray matter in turn associated with objective reduction of physical activity. Cadmium induces neuronal death in cortical neurons through a combined mechanism of apoptosis and necrosis and it could then be hypothesized that cadmium-induced neuronal cell death is responsible for some of the effects of cadmium on the central nervous system, i.e. a decrease in attention level and memory in exposed humans as well as to a diminished ability for training and learning in rats, that are symptoms typical of ME/CFS. This hypothesis can be tested by measuring cadmium exposure in a cohort of ME/CFS patients compared with matched healthy controls, and by measuring gray matter volume in un-exposed healthy controls, exposed non-ME/CFS subjects, un-exposed ME/CFS patients and exposed ME/CFS patients. In addition, we hypothesize that cadmium exposure could be associated with reduced cerebral blood flow in ME/CFS patients because of the disruptive effects of cadmium on angiogenesis. In fact, cadmium inhibits angiogenesis and low global cerebral flow is associated with abnormal brain neuroimaging results and brain dysfunction in the form of reduced cognitive testing scores in ME/CFS patients. This hypothesis can be tested by measuring cerebral cortex blood flow in un-exposed healthy controls, exposed non-ME/CFS subjects, un-exposed ME/CFS patients and exposed ME/CFS patients. If our hypothesis is demonstrated correct, the consequences could affect prevention, early diagnosis, and treatment of ME/CFS. Implications in early diagnosis could entail the evaluation of symptoms typical of ME/CFS in cadmium-exposed subjects as well as the search for signs of exposure to cadmium in subjects diagnosed with ME/CFS. Nutritional supplementation of magnesium and zinc could then be considered, since these elements have been proposed in the prophylaxis and therapy of cadmium exposure, and magnesium was demonstrated effective on ME/CFS patients' symptom profiles.

Increasing orthostatic stress impairs neurocognitive functioning in chronic fatigue syndrome with postural tachycardia syndrome

CFS (chronic fatigue syndrome) is commonly co-morbid with POTS (postural tachycardia syndrome). Individuals with CFS/POTS experience unrelenting fatigue, tachycardia during orthostatic stress and ill-defined neurocognitive impairment, often described as 'mental fog'. We hypothesized that orthostatic stress causes neurocognitive impairment in CFS/POTS related to decreased CBFV (cerebral blood flow velocity). A total of 16 CFS/POTS and 20 control subjects underwent graded tilt table testing (at 0, 15, 30, 45, 60 and 75°) with continuous cardiovascular, cerebrovascular, and respiratory monitoring and neurocognitive testing using an n-back task at each angle. The n-back task tests working memory, concentration, attention and information processing. The n-back task imposes increasing cognitive challenge with escalating (0-, 1-, 2-, 3- and 4-back) difficulty levels. Subject dropout due to orthostatic presyncope at each angle was similar between groups. There were no n-back accuracy or RT (reaction time) differences between groups while supine. CFS/POTS subjects responded less correctly during the n-back task test and had greater nRT (normalized RT) at 45, 60 and 75°. Furthermore, at 75° CFS/POTS subjects responded less correctly and had greater nRT than controls during the 2-, 3- and 4-back tests. Changes in CBFV were not different between the groups and were not associated with n-back task test scores. Thus we conclude that increasing orthostatic stress combined with a cognitive challenge impairs the neurocognitive abilities of working memory, accuracy and information processing in CFS/POTS, but that this is not related to changes in CBFV. Individuals with CFS/POTS should be aware that orthostatic stress may impair their neurocognitive abilities.

What to do about attention and memory problems in children with CFS/ME: a neuropsychological approach

Our recent research has shown that children with chronic fatigue syndrome/myalgic encephalomyopathy (CFS/ME) describe problems with focused attention, sustained attention, recall and stress. Neuropsychological testing demonstrated lower scores for sustained attention, switching attention, divided attention, auditory learning and immediate recall compared to normative data. This paper describes what is currently known about memory and attention problems in children with CFS/ME and suggests a variety of strategies that could be used to overcome these difficulties.

Cognitive deficits in patients with chronic fatigue syndrome compared to those with major depressive disorder and healthy controls

OBJECT

Chronic fatigue syndrome (CFS) patients report usually cognitive complaints. They also have frequently comorbid depression that can be considered a possible explanation for their cognitive dysfunction. We evaluated the cognitive performance of patients with CFS in comparison with a control group of healthy volunteers and a group of patients with MDD.

PATIENTS AND METHODS

Twenty-five patients with CFS, 25 patients with major depressive disorder (MDD), and 25 healthy control subjects were given standardized tests of attention, working memory, and verbal and visual episodic memory, and were also tested for effects related to lack of effort/simulation, suggestibility, and fatigue.

RESULTS

Patients with CFS had slower phasic alertness, and also had impaired working, visual and verbal episodic memory compared to controls. They were, however, no more sensitive than the other groups to suggestibility or to fatigue induced during the cognitive session. Cognitive impairments in MDD patients were strongly associated with depression and subjective fatigue; in patients with CFS, there was a weaker correlation between cognition and depression (and no correlation with fatigue).

CONCLUSIONS

This study confirms the presence of an objective impairment in attention and memory in patients with CFS but with good mobilization of effort and without exaggerated suggestibility.

[The role of depression in cognitive impairment in patients with chronic fatigue syndrome]

BACKGROUND AND OBJECTIVE

To analyze the role of depression in cognitive deficits of patients with chronic fatigue syndrome (CFS).

PATIENTS AND METHODS

57 women with CFS were assessed by neuropsychological tests that included measures of attention: CalCap, Mental control of the WMS-III, PASAT, forward and backward digits (WAIS-III), symbol digit modalities test (SDMT); executive functions: Stroop Test, Trail Making Test (TMT A y B), FAS, Tower of London; memory: Auditory-Verbal Learning Test (AVL), Rey Complex Figure (RCF), and psychomotor skills: Grooved Pegboard. The raw scores on the tests were adjusted according to normative data and transformed to T scores. The sample was divided into two groups based on the presence or absence of depression, assessed by clinical interview and administration of the Hospital Anxiety and Depression Scale (HADS). This study compared neuropsychological test scores between the two groups.

RESULTS

CFS patients showed cognitive deficit in attention and executive functions, regardless of the presence of depression. There were no significant differences between the two CFS groups.

CONCLUSIONS

The cognitive impairments in patients with CFS are not secondary to the presence of depression. These results should be taken into account in the implementation of therapeutic programs in these patients.

Cognitive functioning in chronic fatigue syndrome: a meta-analysis

BACKGROUND

Cognitive problems are commonly reported in persons with chronic fatigue syndrome (CFS) and are one of the most disabling symptoms of this condition. A number of cognitive deficits have been identified, although the findings are inconsistent and hindered by methodological differences. The current study therefore conducted a meta-analysis of research examining cognitive functioning in persons with CFS in order to identify the pattern and magnitude of any deficits that are associated with this condition.

METHOD

A comprehensive search of the PubMed and PsycINFO databases for studies that examined cognitive functioning in CFS between 1988 and 2008 identified 50 eligible studies. Weighted Cohen's d effect sizes, 95% confidence intervals and fail-safe Ns were calculated for each cognitive score.

RESULTS

Evidence of cognitive deficits in persons with CFS was found primarily in the domains of attention, memory and reaction time. Deficits were not apparent on tests of fine motor speed, vocabulary, reasoning and global functioning.

CONCLUSIONS

Persons with CFS demonstrate moderate to large impairments in simple and complex information processing speed and in tasks requiring working memory over a sustained period of time.

Orthostatic symptoms predict functional capacity in chronic fatigue syndrome: implications for management

OBJECTIVES

To establish the relationship between the functional impairment experienced by Chronic fatigue syndrome (CFS) patients and the symptoms frequently experienced by those with CFS; specifically cognitive impairment, fatigue and orthostatic symptoms.

DESIGN

Cross sectional questionnaire survey.

SETTING

Specialist CFS Clinical Service.

SUBJECTS

Ninety-nine Fukuda diagnosed CFS and 64-matched controls.

MAIN OUTCOME MEASURES

Symptom and functional assessment tools completed and returned by post included; PROMIS HAQ (Patient-Reported Outcomes Measurement Information System, Health Assessment Questionnaire), CFQ (Cognitive Failures Questionnaire), FIS (Fatigue Impact Scale) and OGS (Orthostatic Grading Scale) assessment tools.

RESULTS

CFS patients experience greater functional impairment than controls [mean (95% CI) PROMIS HAQ scores CFS 36 (31-42) vs. controls 6 (2-10); P < 0.0001], especially in the functional domains of activities and reach. Poorer functional ability impairment is significantly associated with greater cognitive impairment (P = 0.0002, r = 0.4), fatigue (P < 0.0001, r = 0.5) and orthostatic symptoms (P < 0.0001, r = 0.6). However, only orthostatic symptoms (OGS) independently associated with functional impairment (beta = 0.4, P = 0.01).

CONCLUSION

Treatment of orthostatic symptoms in CFS has the potential to improve functional capacity and so improve quality of life.

Perspectives on fatigue from the study of chronic fatigue syndrome and related conditions

Fatigue is a symptom whose causes are protean and whose phenotype includes physical, mood, and behavioral components. Chronic fatigue syndrome (CFS) is an illness that has strong biological underpinnings and no definite etiology. Diagnostic criteria established by the Centers for Disease Control and Prevention have helped classify CFS as an overlap of mood, behavioral, and biological components. These include the presence of fatigue for more than 6 months associated with a diminution of functional activity and somatic symptoms, and pain not attributable to a specific diagnosis or disease. Four of the following criteria need to be present: sore throat, impaired memory or cognition, unrefreshing sleep, postexertional fatigue, tender glands, aching stiff muscles, joint pain, and headaches. Many researchers have observed that CFS shares features in common with other somatic syndromes, including irritable bowel syndrome, fibromyalgia, and temporomandibular joint dysfunction. Correlations between inflammation and infection, augmented sensory processing, abnormalities of neurotransmitters, nerve growth factors, low levels of serotonin and norepinephrine, abnormalities of homeostasis of the stress system, and autonomic dysfunction may be hallmarks of CFS. The relative contributions of each of these abnormalities to the profound fatigue associated with CFS need to be explored further to better evaluate and treat the syndrome.

EEG source analysis of chronic fatigue syndrome

Sixty-one dextral, unmedicated women with chronic fatigue syndrome (CFS) diagnosed according to the Fukuda criteria (1994) and referred for investigation by rheumatologists and internists were studied with quantitative EEG (43 channels) at rest with eyes open and during verbal and spatial cognitive activation. The EEGs from the patients were compared with recordings from 80 dextral healthy female controls. Only those subjects who could provide 20 1-s artefact-free segments of EEG were admitted into the study. The analysis consisted of the identification of the spatial patterns in the EEGs that maximally differentiated the two groups and the estimation of the cortical source distributions underlying these patterns. Spatial patterns were analyzed in the alpha (8-13Hz) and beta (14-20Hz) bands and the source distributions were estimated using the Borgiotti-Kaplan BEAMFORMER algorithm. The results indicate that the spatial patterns identified were effective in separating the two groups, providing a minimum correct retrospective classification rate of 72% in both frequency bands while the subjects were at rest to a maximum of 83% in the alpha band during the verbal cognitive condition. Underlying cortical source distributions showed significant differences between the two groups in both frequency bands and in all cognitive conditions. Lateralized cortical differences were evident between the two groups in the both frequency bands during both the verbal and spatial cognitive conditions. During these active cognitive conditions, the CFS group showed significantly greater source-current activity than the controls in the left frontal-temporal-parietal regions of the cortex.

Hyperthermia impairs short-term memory and peripheral motor drive transmission

The aims of this study were to determine (i) the effect of passive hyperthermia on motor drive and cognitive function, and (ii) whether head cooling can limit the hyperthermia-induced alterations. Sixteen subjects were randomly exposed for 2 h to three different conditions: control (Con, 20 degrees C), hot (Hot, 50 degrees C) and hot head cool (HHC--where cold packs were applied to the head under Hot conditions). Three cognitive tests measuring attention and two measuring memory were performed. Neuromuscular testing included electrically evoked muscle action potentials (M-waves) and reflex waves (H-reflex) at rest and during brief (4-5 s) and sustained (120 s) maximal voluntary contractions (MVC) of the plantar flexors. All the tests were performed in the environmental room. During brief MVC, torque was significantly lower in both Hot and HHC as compared to Con (P < 0.05). The decrease in muscle activation was significant in Hot (P < 0.05) but not in HBC (P = 0.07). This was accompanied by peripheral failures in the transmission of the neural drive at both spinal (significant decrements in H-reflexes and V-waves, P < 0.05) and neuromuscular junction (significant decrements in M-waves, P < 0.05) levels. During sustained MVC, muscle activation was further depressed (P < 0.05) without any concomitant failures in M-waves, suggesting neural activation adjustments occurring probably at the supraspinal level. Cerebral perturbations were confirmed by significant decrements in both memory tests in Hot as compared with Con (P < 0.05) but not in simple tests (attention tests) that were not affected by hyperthermia. The decrement in memory capacity suggested the existence of frontal lobe activity impairments. Thus, HHC preserved memory capacity but not the visual memory.