Ashley Craig

A critical review of the psychophysiology of driver fatigue

Driver fatigue is a major cause of road accidents and has implications for road safety. This review discusses the concepts of fatigue and provides a summary on psychophysiological associations with driver fatigue. A variety of psychophysiological parameters have been used in previous research as indicators of fatigue, with electroencephalography perhaps being the most promising. Most research found changes in theta and delta activity to be strongly linked to transition to fatigue. Therefore, monitoring electroencephalography during driver fatigue may be a promising variable for use in fatigue countermeasure devices. The review also identified anxiety and mood states as factors that may possibly affect driver fatigue. Furthermore, personality and temperament may also influence fatigue. Given the above, understanding the psychology of fatigue may lead to better fatigue management. The findings from this review are discussed in the light of directions for future studies and for the development of fatigue countermeasures.

Driver fatigue: Electroencephalography and psychological assessment

Fatigue has major implications for transportation system safety; therefore, investigating the psychophysiological links to fatigue could enhance our understanding and management of fatigue in the transport industry. This study examined the psychophysiological changes that occurred during a driver simulator task in 35 randomly selected subjects. Results showed that significant electroencephalographic changes occur during fatigue. Delta and theta activity were found to increase significantly during fatigue. Heart rate was significantly lower after the driving task. Blink rate also changed during the fatigue task. Increased trait anxiety, tension-anxiety, fatigue-inertia and reduced vigor-activity were shown to be associated with neurophysiological indicators of fatigue such as increased delta and theta activity. The results are discussed in light of directions for future studies and for the development of a fatigue countermeasure device.

DEVELOPMENT OF AN ALGORITHM FOR AN EEG-BASED DRIVER FATIGUE COUNTERMEASURE

PROBLEM Fatigue affects a drivers ability to proceed safely. Driver-related fatigue and/or sleepiness are a significant cause of traffic accidents, which makes this an area of great socioeconomic concern. Monitoring physiological signals while driving provides the possibility of detecting and warning of fatigue. The aim of this paper is to describe an EEG-based fatigue countermeasure algorithm and to report its reliability. METHOD Changes in all major EEG bands during fatigue were used to develop the algorithm for detecting different levels of fatigue. RESULTS The software was shown to be capable of detecting fatigue accurately in 10 subjects tested. The percentage of time the subjects were detected to be in a fatigue state was significantly different than the alert phase (P<.01). DISCUSSION This is the first countermeasure software described that has shown to detect fatigue based on EEG changes in all frequency bands. Field research is required to evaluate the fatigue software in order to produce a robust and reliable fatigue countermeasure system. IMPACT ON INDUSTRY The development of the fatigue countermeasure algorithm forms the basis of a future fatigue countermeasure device. Implementation of electronic devices for fatigue detection is crucial for reducing fatigue-related road accidents and their associated costs.

Psychological morbidity and spinal cord injury: a systematic review

Study Design:A systematic review of the literature concerning the nature of the psychological morbidity in people with spinal cord injury (SCI).Objectives:SCI is believed to place the individual at a high risk of psychological morbidity. The objective of this paper was to examine systematically the prevalence of negative psychological states in people with SCI, as well as to explore mediating and contextual factors.Methods:Search engines such as Medline and PsycInfo were systematically searched using specific key words, such as SCI, depression, anxiety and so on. Only studies that fulfilled certain criteria such as the use of valid measures in assessing psychological morbidity were used in the review process.Results:The systematic review revealed that clarification is still needed concerning the psychological consequences of people with SCI. However, findings suggest that approximately 30% of people with SCI are at risk of having a depressive disorder although in rehabilitation, and approximately 27% are at risk of having raised depressive symptoms when living in the community. The review also established that people with SCI have higher comparative risks of anxiety disorder, elevated levels of anxiety, feelings of helplessness and poor quality of life (QOL).Conclusion:People with SCI have an increased risk of suffering debilitating levels of psychological morbidity. Future research needs to clarify the extent and nature of psychological morbidity following SCI by conducting prospective and comprehensive research in large heterogeneous samples of people with SCI during the rehabilitation phase and following reintegration into the community.

The impact of stuttering on the quality of life in adults who stutter.

UNLABELLED Stuttering is an involuntary fluency disorder that is not uncommon in society. However, the impact of stuttering on a composite measure such as quality of life has rarely been estimated. Quality of life (QOL) assesses the well-being of a person from a multidimensional perspective, and valid and reliable general QOL measures are available that can be used to estimate the impact of stuttering on QOL. This study involved the use of a general measure of QOL called the Medical Outcomes Study Short Form-36 (SF-36) in order to assess the impact of stuttering in 200 adults who stutter (AWS). Comparisons to 200 adults of similar age and sex ratio who do not stutter were made so that the unique contribution of stuttering on QOL could be estimated. Findings indicated that stuttering does negatively impact QOL in the vitality, social functioning, emotional functioning and mental health status domains. Results also tentatively suggest that people who stutter with increased levels of severity may have a higher risk of poor emotional functioning. These findings have implications for treatment such as the necessity to address the emotional and psychological aspects of QOL in AWS and the need for additional clinical resources to be invested in stuttering treatment. EDUCATIONAL OBJECTIVES The reader will be able to: (a) summarize the method used in quality of life assessment using the SF-36; (b) describe the impact of stuttering on the quality of life of adults who stutter; (c) compare the impact of stuttering to the quality of life of adults who do not stutter; (d) describe the relationship between frequency of stuttering and quality of life.

SOCIAL ANXIETY DISORDER IN ADULTS WHO STUTTER

Background: The nature and prevalence of social anxiety disorder (social phobia (SP)) in people who stutter is uncertain, and DSM‐IV differential diagnosis guidelines make it difficult to classify an adult who stutters (AWS) with SP as it is assumed any social anxiety symptoms will be a consequence of their stuttering. The aim of this study was to determine the spot prevalence of SP in AWS and to investigate differences in social anxiety between AWS and controls who do not stutter. Methods: The study involved a comprehensive assessment of 200 AWS and 200 adults who do not stutter similar in age and sex ratio. Measures included stuttering severity, health status, self‐report measures of social anxiety as well as a structured diagnostic interview for SP for randomly selected sub‐group of 50 from each group. Results: The AWS were found to have significantly raised trait and social anxiety, as well as significantly increased risk of SP in comparison to the controls. Findings indicated a SP spot prevalence of at least 40% in AWS, and for them to be at high risk of having Generalized SP. Conclusions: It is concluded that the DSM‐IV diagnostic guidelines for diagnosing SP in AWS could result in professional confusion and have possible negative mental health ramifications. Implications for the psychological and medical treatment of AWS are discussed. Depression and Anxiety, 2010.

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.

Anxiety and depression over the first year of spinal cord injury: a longitudinal study.

The literature concerning the psychological consequences following spinal cord injury (SCI) indicates a discordance between clinical impressions and empirical research. Although many studies report that psychological morbidity is not an inevitable consequence of SCI, much of this research is characterised by methodological inadequacies and the conclusions are therefore tenuous. The present study assessed 41 persons with SCI for depression and anxiety using objective psychological measures on three occasions over the first year of SCI and compared them with 41 able bodied controls matched for age, sex, education and, as far as possible, occupation. Results demonstrated significant differences between the two groups, with the SCI group being more anxious and depressed. However, psychological morbidity was not an inevitable consequence of SCI, with group means reflecting mild levels of depression and anxiety. No significant differences were found across time and no interactions between groups and time were detected. Implications for the treatment of SCI are discussed.

Electroencephalographic slowing and reduced reactivity in neuropathic pain following spinal cord injury.

Study Design:Brain wave activity in people with paraplegia, with and without neuropathic pain, was compared to brain wave activity in matched able-bodied controls.Objectives:To investigate whether spinal cord injury with neuropathic pain is associated with a slowing of brain wave activity.Setting:Australia.Methods:Electroencephalographic (EEG) data were collected in the eyes open (EO) and eyes closed (EC) states from 16 participants with paraplegia (eight with neuropathic pain and eight without pain) and matched able-bodied controls. Common EEG artefacts were removed using independent component analysis (ICA). Peak frequency in the θ–α band and EEG power in the δ, θ, α and β frequency bands were compared between groups.Results:The results show significant slowing of the EEG in people with neuropathic pain, consistent with the presence of thalamocortical dysrhythmia (TCD). Furthermore, people with neuropathic spinal cord injury (SCI) pain had significantly reduced EEG spectral reactivity in response to increased or decreased sensory input flowing into the thalamocortical network, as modulated by the eyes open and eyes closed states.Conclusion:The results provide further evidence for alterations in brain electric activity that may underlie the development of neuropathic pain following SCI.

Electroencephalography Activity Associated with Driver Fatigue: Implications for a Fatigue Countermeasure Device

Abstract This paper reviews the association between electroencephalography (EEG) activity and driver fatigue. The current literature shows substantial evidence of changes in brain wave activity, such as simultaneous changes in slow-wave activity (e.g., delta and theta activity) as well as alpha activity during driver fatigue. It is apparent from the literature review that EEG is a promising neurophysiological indicator of driver fatigue and has the potential to be incorporated into the development of a fatigue countermeasure device. The findings from this review are discussed in the light of directions for future fatigue research studies.