Fatigue: Biomedicine, Health & Behavior - Volume 2, Issue 1, 2014

Volume 2, Issue 1, 2014

 * Our first anniversary, Editorial by Fred Friedberg First Page Preview
 * Fatigue in multiple sclerosis "Abstract - Background: Fatigue is the most commonly reported symptom in multiple sclerosis (MS). Purpose: This brief narrative review addresses the clinical features, pathophysiology, and management of MS fatigue, as well as the varied approaches to its definition and measurement. Methods: A literature search was conducted through Medline of studies published since 1984, with a focus on findings reported since 2008. Results: Studies of MS fatigue have primarily relied on the definition of fatigue as a subjective sense of tiredness measured through self-report. Additional studies have measured fatigability in MS, as demonstrated by a decline in cognitive or motor performance over time. The pathogenesis of fatigue remains poorly understood but disease characteristics, including structural and physiologic cerebral alterations as well as immune, endocrine, and psychological factors, may all contribute to its expression. Fatigue therapy has included pharmacologic approaches which have had either methodological limitations (e.g., small sample sizes) or inconclusive results and non-pharmacologic interventions, some of which have been effective in reducing fatigue. Conclusions: Fatigue remains a challenging symptom in MS. The most effective measurement approaches will likely be multidimensional and include both subjective and objective indicators, whereas therapy will likely require more than one type of intervention."
 * The effect of caffeine ingestion on coincidence anticipation timing, perceived exertion, and leg pain during submaximal cycling "Abstract - Background: Caffeine ingestion has been purported to beneficially influence cognitive performance during exercise-induced fatigue. Purpose: To examine the impact of caffeine ingestion on coincidence anticipation performance (the ability to judge when a moving stimulus will arrive at a target) during submaximal cycling. Methods: Twenty-five young adults (13 males, 12 females) undertook two 60 min cycling trials at 60% VO2 max, 60 min following ingestion of a caffeine or placebo solution in a randomized order. Anticipation timing was measured prior to ingestion, 55 min post-ingestion (before exercise), and then at 15 min intervals during the cycling bout. Timing accuracy was assessed using error scores. In addition, heart rate (HR), ratings of perceived exertion (RPE), and muscle pain perception were measured. Results: For anticipation timing, absolute error was significantly lower (p = 0.001) in the caffeine condition at post-ingestion (before exercise), and 30, 45, and 60 min during exercise. Variable error was also lower (p = 0.003) in the caffeine condition irrespective of time point. Heart rate was significantly higher (p = 0.032), and RPE (p = 0.0001) and pain perception (p = 0.024) were significantly lower from 30 to 60 min exercise duration with caffeine. Conclusions: This study suggests that caffeine ingestion enhances anticipation timing performance and reduces perceived exertion and leg pain during exercise. These findings may have implications for improving sport performance."
 * The role of clinical guidelines for chronic fatigue syndrome/myalgic encephalomyelitis in research settings "Abstract - Background: Chronic fatigue syndrome, also known as myalgic encephalomyelitis (CFS/ME) is a particularly difficult illness to identify. To aid in classifying patients for research as well as clinical care, potential cases may be evaluated according to clinical guidelines. Purpose: The purpose of this paper is to provide an overview of three sets of guidelines currently available: the Centers for Disease Control & Prevention (CDC) Toolkit; the International Association for Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (IACFS/ME) Primer; and the International Consensus Primer. Methods: These guidelines were examined and compared with respect to required symptoms, laboratory and investigative protocols, and exclusionary and comorbid conditions. The comparisons were also intended to evaluate the guidelines in light of new research that advances the clinical understanding of CFS/ME and assists in identifying patients. Results: Guidelines vary significantly in the symptoms and comorbidities considered in light of the differing symptom requirements of three case definitions. There is also no specification on how symptoms should be measured, contributing to the significant heterogeneity found in CFS/ME. Conclusions: Further revision of clinical guidelines, preferably based on a definition that is well-informed by current empirical studies, is recommended to ensure that guidelines are applied with consistency and understanding in both research and clinical settings."
 * Examining case definition criteria for chronic fatigue syndrome and myalgic encephalomyelitis "Abstract - Background: Considerable controversy has transpired regarding the core features of myalgic encephalomyelitis (ME) and chronic fatigue syndrome (CFS). Current case definitions differ in the number and types of symptoms required. This ambiguity impedes the search for biological markers and effective treatments. Purpose: This study sought to empirically operationalize symptom criteria and identify which symptoms best characterize the illness. Methods: Patients (n = 236) and controls (n = 86) completed the DePaul Symptom Questionnaire, rating the frequency and severity of 54 symptoms. Responses were compared to determine the threshold of frequency/severity ratings that best distinguished patients from controls. A Classification and Regression Tree (CART) algorithm was used to identify the combination of symptoms that most accurately classified patients and controls. Results: A third of controls met the symptom criteria of a common CFS case definition when just symptom presence was required; however, when frequency/severity requirements were raised, only 5% met the criteria. Employing these higher frequency/severity requirements, the CART algorithm identified three symptoms that accurately classified 95.4% of participants as patient or control: fatigue/extreme tiredness, inability to focus on multiple things simultaneously, and experiencing a dead/heavy feeling after starting to exercise. Conclusions: Minimum frequency/severity thresholds should be specified in symptom criteria to reduce the likelihood of misclassification. Future research should continue to seek empirical support of the core symptoms of ME and CFS to further progress the search for biological markers and treatments."