Emi Yamano

Effect of a human-type communication robot on cognitive function in elderly women living alone

Summary Background Considering the high prevalence of dementia, it would be of great value to develop effective tools to improve cognitive function. We examined the effects of a human-type communication robot on cognitive function in elderly women living alone. Material/Methods In this study, 34 healthy elderly female volunteers living alone were randomized to living with either a communication robot or a control robot at home for 8 weeks. The shape, voice, and motion features of the communication robot resemble those of a 3-year-old boy, while the control robot was not designed to talk or nod. Before living with the robot and 4 and 8 weeks after living with the robot, experiments were conducted to evaluate a variety of cognitive functions as well as saliva cortisol, sleep, and subjective fatigue, motivation, and healing. Results The Mini-Mental State Examination score, judgement, and verbal memory function were improved after living with the communication robot; those functions were not altered with the control robot. In addition, the saliva cortisol level was decreased, nocturnal sleeping hours tended to increase, and difficulty in maintaining sleep tended to decrease with the communication robot, although alterations were not shown with the control. The proportions of the participants in whom effects on attenuation of fatigue, enhancement of motivation, and healing could be recognized were higher in the communication robot group relative to the control group. Conclusions This study demonstrates that living with a human-type communication robot may be effective for improving cognitive functions in elderly women living alone.

Effort-Reward Imbalance for Learning is Associated with Fatigue in School Children

We examined relationships among fatigue, sleep quality, and effort-reward imbalance for learning in school children. We developed an effort-reward for learning scale in school students and examined its reliability and validity. Self-administered surveys, including the effort reward for leaning scale and fatigue scale, were completed by 1,023 elementary school students (grades 4–6) and 1,361 junior high school students (grades 7–9) at the end of 2006. Effort-reward imbalance for learning was associated with a high incidence of fatigue and sleep problems in elementary and junior high school students of both genders. A good relationship with family was associated with a low fatigue score in junior high school boys, and a good relationship with friends was associated with a low fatigue score in junior high school girls by multiple regression analysis. Fatigue score was associated with effort-reward imbalance and fatigue and quality of sleep in schoolchildren. Fatigue may lead to a decline in school performance, negative health outcomes, or refusal to attend school. These results suggest that it is desirable to consider social support, quality of sleep, and effort-reward imbalance when managing fatigue in school children.

Effects of chicken essence on recovery from mental fatigue in healthy males

Background Fatigue is a common symptom in modern society. There has been a recent resurgence of interest in traditional remedies for fatigue. Chicken essence, which is rich in anserine and carnosine, has been widely taken in Asian countries as a traditional remedy with various aims, including attenuation of physical and mental fatigue. However, the evidence for its efficacy specifically for mental fatigue remains unclear. We examined the effect of essence of chicken on mental fatigue in humans, using our established fatigue-inducing task and evaluation methods. Material/Methods In this placebo-controlled crossover study, 20 healthy male volunteers were randomized to receive daily oral administration of essence of chicken or placebo drink provided by Cerebos Pacific Ltd. via Suntory holdings Ltd. for 4 weeks. The participants performed 2-back test trials as a fatigue-inducing mental task and then had a rest session. Just before and after each session, they completed cognitive task trials focusing on selective attention to evaluate the level of mental fatigue. Results After essence of chicken intake for 1 and 4 weeks, the reaction times on the cognitive task trials after the rest session were significantly shorter than those at baseline, and significant changes were not observed with placebo intake. The reaction times before and after the fatigue-inducing session were not altered by either essence of chicken or placebo intake. Conclusions We showed that daily intake of essence of chicken could be effective for the recovery from mental fatigue and is a promising candidate for use as an anti-fatigue food.

Index markers of chronic fatigue syndrome with dysfunction of TCA and urea cycles

Chronic fatigue syndrome (CFS) is a persistent and unexplained pathological state characterized by exertional and severely debilitating fatigue, with/without infectious or neuropsychiatric symptoms, lasting at least 6 consecutive months. Its pathogenesis remains incompletely understood. Here, we performed comprehensive metabolomic analyses of 133 plasma samples obtained from CFS patients and healthy controls to establish an objective diagnosis of CFS. CFS patients exhibited significant differences in intermediate metabolite concentrations in the tricarboxylic acid (TCA) and urea cycles. The combination of ornithine/citrulline and pyruvate/isocitrate ratios discriminated CFS patients from healthy controls, yielding area under the receiver operating characteristic curve values of 0.801 (95% confidential interval [CI]: 0.711–0.890, P < 0.0001) and 0.750 (95% CI: 0.584–0.916, P = 0.0069) for training (n = 93) and validation (n = 40) datasets, respectively. These findings provide compelling evidence that a clinical diagnostic tool could be developed for CFS based on the ratios of metabolites in plasma.

The neural substrates of physical fatigue sensation to evaluate ourselves: a magnetoencephalography study.

It is important to clarify the neural mechanisms underlying fatigue sensation. There have been several studies which identified brain regions in which the level of the neural activities was correlated with the subjective level of fatigue. However, the neural activity evoked when we evaluate our level of fatigue may not be related to the subjective level of fatigue. Thus, we tried to identify the neural activities caused by the evaluation of the level of fatigue, which may not be related to the subjective level of fatigue. We used magnetoencephalography (MEG) to measure neural activity in 10 healthy participants enrolled in our study. During MEG recordings, participants were asked to evaluate the level of physical fatigue in their right hand in time with execution cues (evaluation session) or to direct attention to their right hand in time with execution cues (control session). Equivalent current dipole (ECD) analysis was performed to localize the neural activity limited to the evaluation session. In the evaluation session, ECDs with mean latencies of approximately 380ms were observed in nine of 10 participants. These were localized in the posterior cingulate cortex (PCC), while in the control session, the ECDs in the same brain region were observed in only two of 10 participants. The proportion of participants in whom ECDs were observed in the PCC in the evaluation session was significantly higher than that in the control session (McNemar test). In addition, the intensities of the ECDs were positively associated with the extent to which the participants successfully evaluated the fatigue in their right hand in the evaluation session. These data suggest that the PCC is involved in the neural substrates associated with self-evaluation of physical fatigue.

Potential Biomarkers of Fatigue Identified by Plasma Metabolome Analysis in Rats

In the present study, prior to the establishment of a method for the clinical diagnosis of chronic fatigue in humans, we validated the utility of plasma metabolomic analysis in a rat model of fatigue using capillary electrophoresis-mass spectrometry (CE-MS). In order to obtain a fatigued animal group, rats were placed in a cage filled with water to a height of 2.2 cm for 5 days. A food-restricted group, in which rats were limited to 10 g/d of food (around 50% of the control group), was also assessed. The food-restricted group exhibited weight reduction similar to that of the fatigued group. CE-MS measurements were performed to evaluate the profile of food intake-dependent metabolic changes, as well as the profile in fatigue loading, resulting in the identification of 48 metabolites in plasma. Multivariate analyses using hierarchical clustering and principal component analysis revealed that the plasma metabolome in the fatigued group showed clear differences from those in the control and food-restricted groups. In the fatigued group, we found distinctive changes in metabolites related to branched-chain amino acid metabolism, urea cycle, and proline metabolism. Specifically, the fatigued group exhibited significant increases in valine, leucine, isoleucine, and 2-oxoisopentanoate, and significant decreases in citrulline and hydroxyproline compared with the control and food-restricted groups. Plasma levels of total nitric oxide were increased in the fatigued group, indicating systemic oxidative stress. Further, plasma metabolites involved in the citrate cycle, such as cis-aconitate and isocitrate, were reduced in the fatigued group. The levels of ATP were significantly decreased in the liver and skeletal muscle, indicative of a deterioration in energy metabolism in these organs. Thus, this comprehensive metabolic analysis furthered our understanding of the pathophysiology of fatigue, and identified potential diagnostic biomarkers based on fatigue pathophysiology.

Fatigue sensation induced by the sounds associated with mental fatigue and its related neural activities: revealed by magnetoencephalography

BackgroundIt has been proposed that an inappropriately conditioned fatigue sensation could be one cause of chronic fatigue. Although classical conditioning of the fatigue sensation has been reported in rats, there have been no reports in humans. Our aim was to examine whether classical conditioning of the mental fatigue sensation can take place in humans and to clarify the neural mechanisms of fatigue sensation using magnetoencephalography (MEG).MethodsTen and 9 healthy volunteers participated in a conditioning and a control experiment, respectively. In the conditioning experiment, we used metronome sounds as conditioned stimuli and two-back task trials as unconditioned stimuli to cause fatigue sensation. Participants underwent MEG measurement while listening to the metronome sounds for 6 min. Thereafter, fatigue-inducing mental task trials (two-back task trials), which are demanding working-memory task trials, were performed for 60 min; metronome sounds were started 30 min after the start of the task trials (conditioning session). The next day, neural activities while listening to the metronome for 6 min were measured. Levels of fatigue sensation were also assessed using a visual analogue scale. In the control experiment, participants listened to the metronome on the first and second days, but they did not perform conditioning session. MEG was not recorded in the control experiment.ResultsThe level of fatigue sensation caused by listening to the metronome on the second day was significantly higher relative to that on the first day only when participants performed the conditioning session on the first day. Equivalent current dipoles (ECDs) in the insular cortex, with mean latencies of approximately 190 ms, were observed in six of eight participants after the conditioning session, although ECDs were not identified in any participant before the conditioning session.ConclusionsWe demonstrated that the metronome sounds can cause mental fatigue sensation as a result of repeated pairings of the sounds with mental fatigue and that the insular cortex is involved in the neural substrates of this phenomenon.

Neural substrates activated by viewing others expressing fatigue: A magnetoencephalography study

The neural substrates of the fatigue sensation have not been totally identified. Several lines of evidence demonstrate that seeing emotional changes in others activates brain regions involved in experiencing similar emotions. We hypothesized that there exists a mirror system regarding the fatigue sensation and that brain regions associated with the fatigue sensation may be activated by viewing other individuals expressing fatigue. In this study, we attempted to identify the neural substrates activated by viewing other fatigued individuals using magnetoencephalography (MEG). Twelve healthy participants were enrolled in our study after providing written informed consent. During MEG recordings, they viewed a set of pictures projected on a screen. The pictures, which were presented in a randomized order, were of a person with a fatigued or neutral facial expression. When participants viewed pictures of people with fatigued expressions, we were able to estimate equivalent current dipoles (ECDs) in the posterior cingulate cortex (PCC) in 9 of 12 participants approximately 300 ms after the onset of each picture presentation. When they viewed pictures of people with neutral expressions, we were not able to estimate corresponding ECDs for any participant. The PCC is the brain region activated by viewing others expressing fatigue, suggesting existence of the shared neural substrates of felt and observed fatigue.

Low visual information-processing speed and attention are predictors of fatigue in elementary and junior high school students

BackgroundFatigue is a common complaint among elementary and junior high school students, and is known to be associated with reduced academic performance. Recently, we demonstrated that fatigue was correlated with decreased cognitive function in these students. However, no studies have identified cognitive predictors of fatigue. Therefore, we attempted to determine independent cognitive predictors of fatigue in these students.MethodsWe performed a prospective cohort study. One hundred and forty-two elementary and junior high school students without fatigue participated. They completed a variety of paper-and-pencil tests, including list learning and list recall tests, kana pick-out test, semantic fluency test, figure copying test, digit span forward test, and symbol digit modalities test. The participants also completed computerized cognitive tests (tasks A to E on the modified advanced trail making test). These cognitive tests were used to evaluate motor- and information-processing speed, immediate and delayed memory function, auditory and visual attention, divided and switching attention, retrieval of learned material, and spatial construction. One year after the tests, a questionnaire about fatigue (Japanese version of the Chalder Fatigue Scale) was administered to all the participants.ResultsAfter the follow-up period, we confirmed 40 cases of fatigue among 118 students. In multivariate logistic regression analyses adjusted for grades and gender, poorer performance on visual information-processing speed and attention tasks was associated with increased risk of fatigue.ConclusionsReduced visual information-processing speed and poor attention are independent predictors of fatigue in elementary and junior high school students.

Cognitive dysfunction in elderly females with depressive symptoms

Summary Background A depressive state is a common symptom in the elderly and often accompanies cognitive impairment. The coexistence of depressive symptoms and cognitive impairment is a serious problem, as it increases adverse outcomes for health, functional status, and mortality. It would thus be of great value to clarify the cognitive dysfunction associated with depressive symptoms. We aimed to identify the cognitive dysfunction, in particular, impairment of the response inhibition component of executive function, associated with depressive symptoms in elderly females using the Simple Color Reaction Test and Modified Stroop Color-Word Test. Material/Methods The study group consisted of 35 elderly women. They performed cognitive function task trials for 9 min. Univariate logistic regression analyses were performed to identify factors associated with the prevalence of the depressive state. Results Longer reaction time and lower correction rate of response inhibition trials were related to the prevalence of the depressive symptoms. Conclusions Impaired function of response inhibition may be a specific feature of the depressive state. Our findings may help clarify the neural mechanisms underlying the depressive state of elderly females.