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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Recently it was hypothesized that the antidepressant response to total sleep deprivation (SD) results from a disinhibition process induced by the increase of tiredness in the course of SD. In the present study, the role of tiredness in the antidepressant response to SD is further investigated. Seventy-two depressed patients scored subjective tiredness and depressed mood three times daily (in the morning, afternoon, and evening) on the days preceding and following SD. It was found that averaged tiredness on the day prior to SD was related to the SD response, when the severity of depression prior to SD had been held statistically constant. Also, when both severity of depression and diurnal variation of mood prior to SD were partialed out, tiredness showed a positive correlation with the SD response: patients who reported a relatively low degree of tiredness on the day preceding SD improved by SD. This result suggests that tiredness has an influence on SD effects, and that this influence is independent from that of the severity of depression. The findings are in accordance with current ideas on the role of tiredness as a mediating factor in the induction of the therapeutic effects of SD.
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PMID:The relationship between tiredness prior to sleep deprivation and the antidepressant response to sleep deprivation in depression. 778 59

Changes in discharge rate of 21 fusimotor neurons to medial gastrocnemius muscle during long-lasting fatiguing contractions of lateral gastrocnemius and soleus muscles were recorded in decerebrate cats with innervation of the same hindlimb preserved. Both the spontaneous activity and reflex responses of fusimotor neurons differed from those found previously in preparations with denervated hindlimb. Higher proportion of units fired at rest at rates above 20 impulses/s, the initial increase in discharge rate at the onset of muscle contraction was markedly prolonged, lasting in the majority of units throughout the muscle contraction, while the late increase in discharge rate developing with muscle fatigue was either absent or short-lasting. It is suggested that the increase in spontaneous firing rate occurs in dynamic fusimotor neurons being supported by afferent inflow from secondary muscle spindle endings from non-contracting muscles, the enhancement of the early responses to be primarily due to recurrent disinhibition and the differences in changes of early and late responses to reflect their partly different origin. The possibility is raised that the late reflex responses are lacking more often in static than in dynamic fusimotor neurons. From the functional point of view the differences in fusimotor reflex responses in innervated versus denervated hindlimb may indicate their susceptibility to modifications by changes in afferent inflow according, supposedly, to the current demands of motor control of the active and/or fatigued muscle.
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PMID:Fusimotor responses to fatiguing muscle contractions in non-denervated hindlimb of decerebrate cats. 796 38

Because binge eating in obese individuals has been postulated to be a reaction to dietary restriction, we examined the recorded food intake of 17 obese women with and 16 obese women without binge eating disorder (BED) during 1-week periods before and 3 months after a very low calorie diet program in order to determine the effects of dietary restriction on binge eating frequency and severity. Before weight loss, rather than reporting severe caloric restriction, women with BED reported greater average energy intake than nonbinge eaters on both a total (2707 vs. 1869 k cal/day, p < .01) and weight-adjusted (25.1 vs. 18.1 kcal/kg, p < .01) basis, with both higher intake on nonbinge days and an increased frequency of binge days. After weight loss, there was no significant difference in energy intake, on either a total or weight-adjusted basis, between subjects with and without BED. Although average daily energy intake fell for both groups after weight loss, only subjects with BED reported significantly decreased energy intake when adjusted for change in body weight. This resulted from decreased intake on nonbinge days and a decreased frequency of binge days. Before weight loss, subjects with BED reported an average energy intake equivalent to 94% of their predicted energy expenditure. Whereas subjects without BED reported intake only 64% of predicted (p = .002). After weight loss, there was no significant difference between subjects with and without BED in the percentage of predicted energy expenditure reported as intake (64% vs. 58%). Restraint was similar in both groups before weight loss, but those with BED reported greater hunger and disinhibition. After weight loss treatment, restraint increased significantly, whereas disinhibition and hunger remained elevated in subjects with BED. Disinhibition, rather than restraint, appears to be a major contributor to the disordered eating of these individuals. Unlike normal-weight women with bulimia nervosa, dietary restriction does not appear to worsen symptoms of binge eating in obese women with BED. Over the short term, subjects with BED may respond to a standard weight loss treatment program with improvements in binge eating behaviors.
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PMID:Recorded food intake of obese women with binge eating disorder before and after weight loss. 817 59

Cushing's disorder and depression present overlapping although not identical psychological symptomatology. In turn, a subset of patients with affective disorders present with hypercortisolemia and disturbances, specifically disinhibition, of the hypothalamic hypophysio adrenal axis (HHAA). Memory disturbances, in particular, biasing toward negative contents, overlapping sleep abnormalities (marked reduction of stages 3 and 4) increased fatigue and loss of energy, attentional deficits and irritability, are just part of the common symptomatology presented by patients with both Cushing's disorder and depression. All of these behavioral manifestations are known to be affected by adrenal steroid hormones. There is consensus that hippocampal structures are a main target for adrenal steroid hormones; hence, these neural regions are some of the most likely mediators of the effects of corticoadrenal steroids on behavior. This paper proposes that an imbalance of adrenal steroids and their metabolites may play a fundamental role in the psychophysiopathology of Cushing's and depressive disorders. The imbalance of these hormones, especially at limbic sites, could distort mood and memory content affecting cognition based on recollection and present experiences. Reestablishing an adrenal balance could therefore be considered as a therapeutic aid in a subset of depressive disorders.
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PMID:Effects of adrenal cortex hormones on limbic structures: some experimental and clinical correlations related to depression. 846 Dec 80

In view of the opposing theories regarding the arousing or de-arousing action of total sleep deprivation (TSD) in producing antidepressant effects, 23 patients with a major depressive disorder were deprived of a night's sleep twice weekly for two weeks, and self-rated their condition 38 times using von Zerssen's scale for depression and, concurrently, Thayer's Activation Deactivation Adjective Check List (AD ACL). Transient relief of depression after TSD, indicated by eight patients, was mimicked by their AD ACL scores, which revealed the same underlying factors as were found in Thayer's studies. TSD appears to be simultaneously arousing (giving more energy) and de-arousing (leading to less tension), while this response takes place against a background of increased tiredness/sleepiness. It is argued that TSD sets off a psychological disinhibition process on the basis of cerebral fatigue; in particular the prefrontal (orbital?) areas of the cerebral cortex may be implicated, possibly in relation to a dampening down of subcortical arousal systems.
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PMID:Self-rated arousal concurrent with the antidepressant response to total sleep deprivation of patients with a major depressive disorder: a disinhibition hypothesis. 1060 54

According to the classification criteria proposed by the American College of Rheumatology, fibromyalgia is a long-standing multifocal pain condition combined with generalised allodynia/hyperalgesia. It is the generalised allodynia/hyperalgesia that distinguishes fibromyalgia from other conditions with chronic musculoskeletal pain. Central sensitisation of nociceptive neurons in the dorsal horn due to activation of N-methyl-D-aspartic acid receptors and disinhibition of pain due to deficient function of the descending inhibitory system are probable pathogenic factors for allodynia/hyperalgesia. Furthermore, chronic pain is a chronic emotional and physical stressor. Chronic stress and chronic sleep disturbance are not specific for fibromyalgia but could be the causes of symptoms like fatigue, cognitive difficulties and other stress-related symptoms. They may also cause neuroendocrinological and immunological aberrations.
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PMID:Fibromyalgia--from syndrome to disease. Overview of pathogenetic mechanisms. 1281 64

The purpose of this work was to investigate the electromyographic (EMG) fatigue representations in muscles of subjects after stroke at the level of motor unit, based on the analysis of mean power frequency (MPF) in the power density spectrum (PDS) for intramuscular EMG and our previous modeling and experiment studies on the neuromuscular transmission failure (NTF). NTF due to the local muscular fatigue had been captured in motor unit signals from healthy subjects during a submaximal fatigue contraction previously. In this study, the EMG signals for the biceps brachii muscles were collected by needle electrodes from the affected and unaffected arms of six hemiplegic subjects after stroke, and from the dominated arm of six healthy subjects during a full maximum voluntary contraction (MVC) and a subsequent 20% MVC. The MPF of EMG trials detected intramuscularly during the full and 20% MVCs, and the parameters of motor unit action potential trains (MUAPTs) during 20% MVC were analyzed in three groups: the normal (from healthy subjects), unaffected (from subjects after stroke), and affected (from subjects after stroke). It was found that during the full MVC the MPFs of the normal and unaffected groups decreased more than the affected when monitored by a moving time window of 2 s. The comparison on the overall MPF during the full MVC for these three groups over the whole time course of the EMG signal (18 s) were: the affected overall MPF was higher than the unaffected (P < 0.05); and the unaffected overall MPF was larger than the normal (P < 0.05). However, no significant decrease in MPF was found for these three groups during 20% MVC. The NTF was captured in most MUAPTs in the groups of the normal and unaffected rather than in the affected group, symbolized by the lowered rates of change (RCs) of firing rate (FR) (P < 0.05), more MUAPTs with positive RCs of maximum oscillation (MO) in MUAPT power density spectra (P < 0.05), and the significant higher RCs of minimum inter-pulse interval (MINI) (P < 0.05) in the normal and unaffected compared to the affected group. Enhanced neural drives to the motor units of the unaffected and affected groups were observed during 20% MVC, which possibly came from the bilateral neural inputs due to the disinhibition of the ipsilateral projections in subjects after stroke. For identifying the fatigue associated with NTF, the motor unit firing parameters, FR, MINI, and MO, were more sensitive than the MPF. The results obtained in this work provided a further understanding on the EMG of the fatigue processes in paretic and non-paretic muscles during voluntary contractions.
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PMID:Firing properties of motor units during fatigue in subjects after stroke. 1631 Oct 42

Tourette syndrome is a neurodevelopmental disorder characterized by motor and vocal tics--rapid, repetitive, stereotyped movements or vocalizations. Tourette syndrome typically has a prepubertal onset, and boys are more commonly affected than girls. Symptoms usually begin with transient bouts of simple motor tics. By age 10 years, most children are aware of nearly irresistible somatosensory urges that precede the tics. These urges likely reflect a defect in sensorimotor gating because they intrude into the child's conscious awareness and become a source of distraction and distress. A momentary sense of relief typically follows the completion of a tic. Over the course of hours, tics occur in bouts, with a regular intertic interval. Tics increase during periods of emotional excitement and fatigue. Tics can become "complex" in nature and appear to be purposeful. Tics can be willfully suppressed for brief intervals and can be evoked by the mere mention of them. Tics typically diminish during periods of goal-directed behavior, especially those that involve both heightened attention and fine motor or vocal control, as occur in musical and athletic performances. Over the course of months, tics wax and wane. New tics appear, often in response to new sources of somatosensory irritation, such as the appearance of a persistent vocal tic (a cough) following a cold. Over the course of years, tic severity typically peaks between 8 and 12 years of age. By the end of the second decade of life, many individuals are virtually tic free. Less than 20% of cases continue to experience clinically impairing tics as adults. Tics rarely occur in isolation, and other coexisting conditions--such as behavioral disinhibition, hypersensitivity to a broad range of sensory stimuli, problems with visual motor integration, procedural learning difficulties, attention-deficit hyperactivity disorder (ADHD), obsessive-compulsive disorder, depression, anxiety, and emotional instability--are often a greater source of impairment than the tics themselves. Emerging behavioral treatments of Tourette syndrome are based in part on an understanding of the moment-to-moment experience of somatosensory urges and motor response. With identification of specific genes of major effect and advances in our understanding of the neural circuitry of sensorimotor gating, habit formation, and procedural memory--together with insights from postmortem brain studies, in vivo brain imaging, and electrophysiologic recordings--we might be on the threshold of a deeper understanding of the phenomenology and natural history of Tourette syndrome.
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PMID:Tourette syndrome: the self under siege. 1697 Aug 64

The present study examines changes in a variety of oculomotoric variables as a function of increasing sleepiness in 129 participants, who have been passed through a broad range of subjective alertness. Up to now, spontaneous eye blinks are the most promising biosignal for in-car sleepiness warnings. Reviewing the current literature on eye movements and fatigue, experimental data are provided including additional indicative oculomotoric parameters; inter-individual differences in the experiments were also assessed. Here, self-rated alertness decreased over six steps on average and proved itself a reliable measurement. Regarding oculomotoric parameters, blink duration, delay of lid reopening, blink interval and standardised lid closure speed were identified as the best indicators of subjective as well as objective sleepiness. Saccadic parameters and fixation durations also showed specific changes with increasing sleepiness. Substantial inter-individual differences in all of these variables were illustrated. Oculomotoric parameters were linked to three different components of sleepiness while driving: a) deactivation; b) decreasing attention, resulting in disinhibition of spontaneous blinks and reflexive saccades; c) increasing attempts of self-activation. Finally, implications for the development of drowsiness detection devices were discussed.
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PMID:Blinks and saccades as indicators of fatigue in sleepiness warnings: looking tired? 1856 59

Neurobehavioral changes observed in patients with brain tumours may appear as cognitive deficits, mood disturbances, changes in behaviour or decreased adaptability (e.g., drowsiness, apathy, loss of spontaneity, fatigue). They are initially subtle, develop insidiously, and their severity often changes. Serious diagnostic problems can be caused by mood disorders, psychotic symptoms, personality changes, from disinhibition to apathy, observed in such patients. The problem in distinguishing them from organic psychiatric disorders, often poses a challenge for psychiatrists, neurologists and general practitioners. We describe a case difficult to diagnose because of apathy, due to a brain tumour in the right frontal lobe, diagnosed as depression. Another difficulty, rather suggesting mood disorder, was rheumatoid arthritis. Thorough and meticulous analysis of clinical data, neuropsychological assessment and neuroimaging diagnosis may help to assess aetiology of the observed disorders which can have similar clinical pictures but various causes.
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PMID:[Depression or apathy? A diagnostic trap: a huge right frontal lobe meningioma diagnosed and treated as mild atypical depression episode--a case study]. 2339 28


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