Nirupama Wijesuriya

Regional brain wave activity changes associated with fatigue

Assessing brain wave activity is a viable strategy for monitoring fatigue when performing tasks such as driving, and numerous studies have been conducted in this area. However, results of a systematic review on changes in brain wave activity associated with fatigue have revealed equivocal findings. This study investigated brain wave activity associated with fatigue in 48 nonprofessional healthy drivers as they participated in a simulated driving task until they fatigued. The results showed that as a person fatigues, slow wave activity increased over the entire cortex, in theta and in alpha 1 and 2 bands, while no significant changes were found in delta wave activity. Substantial increases also occurred in fast wave activity, though mostly in frontal sites. The results suggest that as a person fatigues, the brain loses capacity and slows its activity, and that attempts to maintain vigilance levels lead to increased beta activity.

Developing a model of associations between chronic pain, depressive mood, chronic fatigue, and self-efficacy in people with spinal cord injury.

UNLABELLED Chronic pain, chronic fatigue, and depressive mood are prevalent conditions in people with spinal cord injury (SCI). The objective of this research was to investigate the relationship between these conditions in adults with SCI. Multivariate analysis of variance, contingency analyses, and hierarchical regression were used to determine the nature of the relationship, as well as the contribution to this relationship of self-efficacy, a potential mediator variable. Seventy participants with SCI living in the community completed an assessment regimen of demographic and psychometric measures, including validated measures of pain, fatigue, depressive mood, and self-efficacy. Results indicated that participants with high levels of chronic pain had clinically elevated depressive mood, confusion, fatigue, anxiety and anger, low vigor, and poor self-efficacy. Participants with high chronic pain had 8 times the odds of having depressive mood and 9 times the odds of having chronic fatigue. Regression analyses revealed that chronic pain contributed significantly to elevated depressive mood and that self-efficacy mediated (cushioned) the impact of chronic pain on mood. Furthermore, both chronic pain and depressive mood were shown to contribute independently to chronic fatigue. Implications of these results for managing chronic pain in adults with SCI are discussed. PERSPECTIVE The relationship between pain, negative mood, fatigue, and self-efficacy in adults with SCI was explored. Results support a model that proposes that chronic pain lowers mood, which is mediated (lessened) by self-efficacy, whereas pain and mood independently increase chronic fatigue. Results provide direction for treating chronic pain in SCI.

A controlled investigation into the psychological determinants of fatigue.

Driver fatigue is associated with risks of road accidents that result in injury and death. Research has been limited by several issues such as confusion over definitions, how best to measure fatigue, and the contribution of psychological factors to fatigue. This study addressed these limitations by investigating the relationship between psychological factors and fatigue. Participants were assessed and were required to perform a monotonous task till they tired. Results found few psychological factors to be related to physiological and performance decrement fatigue outcome measures. However, psychological factors were found to correlate consistently with self-reported fatigue. The results suggest that fatigue is associated with a predisposition to be anxious, depressive, less self-assured, more conscientious (rule bound), less socially bold, less adaptable and low vigour. The results indicate that future research should employ a range of fatigue outcome measures in order to best understand what factors contribute to fatigue.

Fatigue and tiredness in people with spinal cord injury

OBJECTIVE Fatigue is a common symptom in people with neurological injury such as spinal cord injury (SCI), though its nature and occurrence in people with SCI are not well understood. The objective of this research was to investigate fatigue and its relationship to factors such as mood states and self efficacy in adult people with SCI compared to able-bodied controls. METHODS Participants included 41 adults with SCI living in the community and 41 able-bodied controls matched for age and sex ratios and education. All participants first completed a comprehensive psychological assessment and were then asked to take part in a 2-3 hour session composed of a regimen of cognitive tasks that required constant concentration and attention. Participants were assessed after completing this task. RESULTS The SCI group was found to have significantly elevated levels of fatigue, as well as elevated depressive mood, anxiety and poor self-efficacy. The SCI group was also found to suffer excessive levels of tiredness as a consequence of the 2-3 hour task. Factors such as depressive mood and poor self-efficacy were shown to increase the risk of excessive tiredness. CONCLUSION People with a neurological injury such as SCI have a high risk of having fatigue and are susceptible to experiencing excessive tiredness when performing extended tasks, and the presence of elevated depressive mood or poor expectations towards self management will increase this susceptibility. Implications for managing fatigue and improving social access in SCI populations are discussed.

Impact of Fatigue on the Health-Related Quality of Life in Persons With Spinal Cord Injury

OBJECTIVE To study the impact of fatigue on health-related quality of life (HR-QOL) associated with spinal cord injury (SCI). DESIGN Matched group design with several independent measures. SETTING University-based laboratory. PARTICIPANTS Persons with SCI (n=41) and an average 16.5 years duration of community living with SCI and a group of able-bodied controls (n=41) with similar sex ratio, age, and level of education. Participants with SCI were enrolled through rehabilitation unit contacts and through advertising in newsletters. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES The main independent measures reported in this article include the Iowa Fatigue Scale and the Medical Outcomes Study 36-Item Short-Form Health Survey. RESULTS As expected, persons with SCI were found to have significantly lower HR-QOL. Fatigue was found to be more prevalent in the SCI group, and was associated with lower HR-QOL in both groups. Factorial analysis of variance indicated significant interactions in which persons with SCI with low fatigue levels had similar HR-QOL to the able-bodied controls regardless of their fatigue level, while persons with SCI with elevated fatigue had significantly reduced HR-QOL. Factors such as age, education, completeness and level of lesion, and community integration were not associated with increased fatigue levels. However, a shorter time since injury was found to be significantly associated with higher levels of fatigue. CONCLUSIONS The Iowa Fatigue Scale data suggest over 50% of the SCI group had elevated fatigue, which was associated with significantly reduced HR-QOL. Research is needed that identifies factors that raise vulnerability to fatigue, and strategies designed to address the negative impacts of fatigue need to be evaluated.

The Relationship Between Spectral Changes in Heart Rate Variability and Fatigue

Fatigue is a prevalent problem in the workplace and a common symptom of many diseases. However, its relationship with the autonomic nervous system, specifically with sympathetic arousal, needs clarification. The objective of this study was to determine the association between fatigue and heart rate variability (HRV). HRV is regarded as an indicator of the autonomic regulation activity of heart rate, specifically sympathetic and parasympathetic activity. Spectral changes in low-frequency (LF; 0.04–0.15 Hz) and high-frequency (HF; 0.15–0.4 Hz) components of HRV have been reported to be associated with distressing conditions such as hemorrhagic shock, acute myocardial infarction, elevated anxiety, and depressed mood. While HRV changes have been found in persons with chronic fatigue syndrome, its association with fatigue in healthy individuals still needs clarification. HRV was assessed in a total of 50 participants who were asked to perform a task until becoming fatigued. Low-frequency HRV activity increased...

Improving classification rates for use in fatigue countermeasure devices using brain activity

Fatigue can be defined as a state that involves psychological and physical tiredness with a range of symptoms such as tired eyes, yawning and increased blink rate. It has major implications for work place and road safety as well as a negative symptom of many acute and chronic illnesses. As such there has been considerable research dedicated to systems or algorithms that can be used to detect and monitor the onset of fatigue. This paper examines using electroencephalography (EEG) signals to classify fatigue and alert states as a function of subjective self-report, driving performance and physiological symptoms. The results show that EEG classification network for fatigue improved from 75% to 80% when these factors are applied, especially when the data is grouped by subjective self-report of fatigue with classification accuracy improving to 84.5%.

Central correlates of impaired information processing in people with spinal cord injury

Summary: This investigation examined the impact of spinal cord injury (SCI) on task-relevant processing using event-related potentials. Thirty-seven participants with chronic SCI and 37 healthy able-bodied controls were tested in this study. An auditory two-tone button press oddball discrimination paradigm was used to evoke the N100, P200, N200, and P300 components of the event-related potential. During the early sensory/perceptual stages of target stimulus processing, the SCI group showed an earlier right posterior P200 latency relative to the controls. In the later more cognitive stages, a pattern of diminished left and right posterior P300 amplitude was also evident. This was further coupled with increased false-positive errors and greater variability of response time in the SCI group. The results of this study indicate that people with SCI show disturbances in inhibitory function and alterations in both early perceptual encoding processes and in later executive functioning that engages contextual/memory-updating operations.

Effects of mental fatigue on 8–13Hz brain activity in people with spinal cord injury

Brain computer interfaces (BCIs) can be implemented into assistive technologies to provide ‘hands-free’ control for the severely disabled. BCIs utilise voluntary changes in ones brain activity as a control mechanism to control devices in the persons immediate environment. Performance of BCIs could be adversely affected by negative physiological conditions such as fatigue and altered electrophysiology commonly seen in spinal cord injury (SCI). This study examined the effects of mental fatigue from an increase in cognitive demand on the brain activity of those with SCI. Results show a trend of increased alpha (8–13Hz) activity in able-bodied controls after completing a set of cognitive tasks. Conversely, the SCI group showed a decrease in alpha activity due to mental fatigue. Results suggest that the brain activity of SCI persons are altered in its mechanism to adjust to mental fatigue. These altered brain conditions need to be addressed when using BCIs in clinical populations such as SCI. The findings have implications for the improvement of BCI technology

The Influence of Self-Efficacy on Mood States in People with Spinal Cord Injury

Objective. Negative mood is prevalent in people with a neurological injury such as spinal cord injury (SCI). However, research is needed for determining those people with SCI who are vulnerable to negative mood states, as well as establishing the influence of self-efficacy, that is, expectations of their control over their lives. The objective of this research was to investigate the protective role that self-efficacy may play in adult people with SCI compared to able-bodied controls. Methods. Participants included 41 adults with SCI living in the community and 41 able-bodied controls similar in age, sex ratio, and education. All participants completed a psychological assessment regimen in a relaxed environment. Measures consisted of validated measures of self-efficacy and negative mood states. Results. The SCI group was found to have significantly elevated levels of depressive mood, anxiety, stress, and poor self-efficacy. SCI participants with low levels of self-efficacy were shown to have significantly elevated levels of depressive mood and anxiety in comparison to those SCI participants with high levels of self-efficacy and able-bodied controls. Conclusions. People with a neurological injury such as SCI are vulnerable to experiencing clinically elevated negative mood states if they have poor expectations of control over their lives. Implications for SCI rehabilitation are discussed.