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Biomedical subjects

Alexander C McFarlane

Publications and source records attributed to Alexander C McFarlane.

At least 19 recordsLinked to original sources
PubMed2006

Hazardous or harmful alcohol use in Royal Australian Navy veterans of the 1991 Gulf War: identification of high risk subgroups.

Elevated alcohol use disorders have been observed in 1991 Gulf War veterans from a variety of countries. This study used a self-report instrument, the Alcohol Use Disorders Identification Test (AUDIT), to ascertain whether any subgroups of 1232 male Royal Australian Navy (RAN) Gulf War veterans were at higher risk of hazardous or harmful alcohol use. Recursive partitioning/classification and regression tree (CART) analysis, followed by logistic regression, found five subgroups among the veterans, with differing risks of AUDIT caseness. The highest risk subgroup comprised current smokers. The other two high risk groups both consisted of former or never smokers of lower rank who were (1) not married, or (2) married, with a current diagnosis of major depression. The above subgroups were over three times as likely to exhibit AUDIT caseness than those who were former or never smokers of higher rank. The findings have important implications for effective development of public health initiatives designed to encourage safe alcohol use among veterans.

Adult↗
PubMed2006

Integrative assessment of brain function in PTSD: brain stability and working memory.

Posttraumatic Stress Disorder (PTSD) is characterized by symptoms of hyperarousal, avoidance and intrusive trauma-related memories and deficits in everyday memory and attention. Separate studies in PTSD have found abnormalities in electroencephalogram EEG, in event-related potential (ERP) and behavioral measures of working memory and attention. The present study seeks to determine whether these abnormalities are related and the extent to which they share this relationship with clinical symptoms. EEG data were collected during an eyes-open paradigm and a one-back working memory task. Behavioral and clinical data (CAPS) were also collected. The PTSD group showed signs of altered cortical arousal as indexed by reduced alpha power and an increased theta/alpha ratio, and clinical and physiological measures of arousal were found to be related. The normal relationship between theta power and ERP indices of working memory was not affected in PTSD, with both sets of measures reduced in the disordered group. Medication appeared to underpin a number of abnormal parameters, including P3 amplitude to targets and the accuracy, though not speed, of target detection. The present study helps to overcome a limitation of earlier studies that assess such parameters independently in different groups of patients that vary in factors such as comorbidity, medication status, gender and symptom profile. The present study begins to shed light on the relationship between these measures and suggests that abnormalities in brain working memory may be linked to underlying abnormalities in brain stability.

Adult↗
PubMed2006

Psychiatric disorder and separation from military service: a 10-year retrospective study.

OBJECTIVE: This study investigated the association between the onset of psychiatric morbidity and separation from military service over a 10-year period (1991-2001). METHOD: The prevalence of affective, anxiety, somatic, and substance use disorders was assessed in 2,215 male Australian Navy personnel with the Composite International Diagnostic Interview. RESULTS: The onset of a psychiatric disorder during military service was related to a 19% greater risk of separation overall. The majority of those leaving military service did so in the first year after symptom onset. Personnel who remained in service past this period had no significantly elevated risk of separation in subsequent years. CONCLUSIONS: Psychiatric morbidity represents a significant potential cost to defense forces. Improved recognition and early management of mental health problems among military personnel may improve retention rates.

Australia↗
PubMed2006

The extent and impact of mental health problems after disaster.

Disasters are events that challenge the individual's ability to adapt, which carries the risk of adverse mental health outcomes including serious posttraumatic psychopathologies. While risk is related to degree of exposure to psychological toxins, the unique vulnerabilities of special populations within the affected community as well as secondary stressors play an important role in determining the nature and amount of morbidity. Disasters in developing countries and those associated with substantial community destruction are associated with worse outcome. Although acute responses are ubiquitous, few disasters lead to posttraumatic psychopathology in the majority of people exposed. However, the shortage of human resources in psychiatry, particularly in developing countries, places a considerable burden on psychiatric services even without the additional constraints imposed by disaster. Hence, disasters are events that invite a public health approach to mental health that better serves the needs of the individual and the affected community. Such an approach considers all available human resources and is intended to mitigate the effects of disaster before serious psychopathologic sequelae arise. This community mental health strategy allows peripheral mental health workers to mediate between survivors and specialized mental health professionals while assisting in removing barriers to treatment. To be effective when disaster occurs, this approach requires careful planning in conjunction with community consultation before implementation of formal disaster mitigation policies.

Community Mental Health Services↗
PubMed2006

Symptomatology and psychopathology of mental health problems after disaster.

A variety of reactions are observed after a major trauma. In the majority of cases these resolve without any long-term consequences. In a significant proportion of individuals, however, recovery may be impaired, leading to long-term pathological disturbances. The most common of these is post-traumatic stress disorder (PTSD), which is characterized by symptoms of reexperiencing the trauma, avoidance and numbing, and hyperarousal. A range of other disorders may also be seen after trauma, and there is considerable overlap between PTSD symptoms and several other psychiatric conditions. Risk factors for PTSD include severe exposure to the trauma, female sex, low socioeconomic status, and a history of psychiatric illness. Although PTSD may resolve in the majority of cases, in some cases risk factors outweigh protective factors, and symptoms may persist for many years. PTSD often coexists with other psychiatric disorders, such as depression, anxiety disorders, and substance abuse, and with physical (somatization) symptoms. There is growing evidence that PTSD does not merely represent a normal response to stress, but rather is mediated by specific neurobiological dysfunctions.

Bereavement↗
PubMed2005

Abnormal frontal and parietal activity during working memory updating in post-traumatic stress disorder.

This study used event-related potentials (ERPs) to investigate the timing and scalp topography of working memory in post-traumatic stress disorder (PTSD). This study was designed to investigate ERPs associated with a specific working memory updating process. ERPs were recorded from 10 patients and 10 controls during two visual tasks where (a) targets were a specific word or (b) targets were consecutive matching words. In the first task, nontarget words are not retained in working memory. In the second task, as in delay-match-to-sample tasks, a non-target word defines a new target identity, so these words are retained in working memory. This working memory updating process was related to large positive ERPs over frontal and parietal areas at 400-800 ms, which were smaller in PTSD. Estimation of cortical source activity indicated abnormal patterns of frontal and parietal activity in PTSD, which were also observed in regional cerebral blood flow [Clark, C.R., McFarlane, A.C., Morris, P., Weber, D.L., Sonkkilla, C., Shaw, M., Marcina, J., Tochon-Danguy, H., Egan, G., 2003. Cerebral function in posttraumatic stress disorder during verbal working memory updating: a positron emission tomography study. Biological Psychiatry 53, 474-481]. Frontal and parietal cortex are known to be involved in distributed networks for working memory processes, interacting with medial temporal areas during episodic memory processes. Abnormal function in these brain networks helps to explain everyday concentration and memory difficulties in PTSD.

Brain Mapping↗
PubMed2005

War zone stress without direct combat: the Australian naval experience of the Gulf War.

This study examines psychological stressors reported by Australian Navy Gulf War veterans in relation to the 1991 Gulf War and other military service. Using a 44-item questionnaire, veterans reported few direct-combat encounters during the Gulf War; however, they reported many other stressful experiences, including fear of death and perceived threat of attack, more frequently in relation to the Gulf War than other military service. Reporting of stressful experiences was associated with younger age, lower rank, and deployment at the height of the conflict. These experiences may partly explain increased rates of psychological disorders previously demonstrated in this Navy veteran population. Findings highlight the importance of documenting war experiences in close proximity to deployment, and developing war exposure instruments which include naval activities and which reflect stressors other than those related to direct combat.

Adult↗
PubMed2005

Clozapine improves working memory updating in schizophrenia.

This study investigated the effect of clozapine on working memory in 15 subjects with schizophrenia, using an event related potential paradigm designed to separate components reflecting working memory updating from components related to target detection and response. Compared to matched controls and prior to treatment with clozapine, subjects with schizophrenia had N1, P3 and Late Slow Wave abnormalities indicating impairment in early stimulus evaluation and subsequent working memory functions. Treatment with clozapine was associated with normalization of the P3 and Late Slow Waves, indicating improvement in working memory updating and executive processing. There was also a partial normalization of N1 amplitude, suggesting improvement in early stimulus evaluation.

Adult↗
PubMed2005

Psychopathology following trauma: the role of subjective experience.

BACKGROUND: The DSM-IV definition of posttraumatic stress disorder (PTSD) widened the stressor criterion to include objective (A1) and subjective (A2) components. The prevalence of Criterion A2, and its association with traumatic memory and psychopathology, was examined in a large community sample. METHOD: The presence of Criterion A2 and traumatic memories, as well as DSM-IV anxiety, affective and substance use disorders, were examined in a community sample of 6104 adults with a history of traumatic exposure. RESULTS: Most individuals met Criterion A2 (76%), with higher prevalence in females (81%) than males (69%). A2 was more common following certain traumas (such as assaultive violence). Excluding those people with PTSD, prevalence of most psychiatric disorders was higher in those who met Criterion A2 than in those who only met Criterion A1. Only 3% of those who did not meet A2 went on to suffer persistent traumatic memories. The prevalence of psychiatric disorders was higher in those with A2 and traumatic memories than in those with A2 and no traumatic memories. LIMITATIONS: The retrospective nature of the data raises the potential for reporting biases. The data set allowed only one of several possible predictors of posttraumatic adjustment to be examined and only 12-month, and not lifetime, prevalence of psychiatric conditions was available. CONCLUSIONS: The experience of powerful emotions at the time of traumatic exposure is common and is associated with increased prevalence not only of PTSD, but also of a range of other psychiatric conditions. Traumatic memories may mediate this association.

Adult↗
PubMed2005

Integrative assessment of brain and cognitive function in post-traumatic stress disorder.

The present study combined neuropsychological and electrophysiological measures to obtain a comprehensive profile of the everyday attentional and memory dysfunction reported in PTSD. The event-related potential (ERP) literature has consistently found abnormalities in late components (N2, P3) reflecting working memory (WM) function. However, the neuropsychological profile reported in the literature has considerable variation. The present study examined ERP activity in 33 PTSD participants and matched controls during a standard two-tone auditory oddball task. Neuropsychological assessment was carried out using a task battery assessing a wide range of cognitive functions. Consistent with previous work, the PTSD group showed delayed N2 latency and reduced P3 target amplitude, together with slower and less accurate target detection. Scalp topography provided evidence of widespread abnormality during WM function, but with strongest effects broadly over the left hemisphere. Neuropsychological testing found concomitant difficulties on factorial measures of verbal memory retention/access and sustained attention but enhanced performance on measures of immediate recall. This integrative pattern of effects reflects a specific impairment in the operation of working memory systems that guide ongoing, planned behavior and that facilitate the acquisition and retention of new memories.

Adult↗
PubMed2004

War-related psychological stressors and risk of psychological disorders in Australian veterans of the 1991 Gulf War.

BACKGROUND: Questions remain about the long-term health impacts of the 1991 Gulf War on its veterans. AIMS: To measure psychological disorders in Australian Gulf War veterans and a military comparison group and to explore any association with exposure to Gulf War-related psychological stressors. METHOD: Prevalences of DSM-IV psychological disorders were measured using the Composite International Diagnostic Interview. Gulf War-related psychological stressors were measured using a service experience questionnaire. RESULTS: A total of 31% of male Gulf War veterans and 21% of the comparison group met criteria for a DSM-IV disorder first present in the post-Gulf War period. The veterans were at greater risk of developing post-Gulf War anxiety disorders including post-traumatic stress disorder, affective disorders and substance use disorders. The prevalence of such disorders remained elevated a decade after deployment. The findings can be explained partly as a 'war-deployment effect'. There was a strong dose-response relationship between psychological disorders and number of reported Gulf War-related psychological stressors. CONCLUSIONS: Service in the 1991 Gulf War is associated with increased risk of psychological disorders and these are related to stressful experiences.

Adult↗
PubMed2003

Cerebral function in posttraumatic stress disorder during verbal working memory updating: a positron emission tomography study.

BACKGROUND: This study examined cerebral function in posttraumatic stress disorder (PTSD) during the updating of working memory to trauma-neutral, verbal information. METHODS: Ten PTSD and matched control subjects completed a visuoverbal target detection task involving continuous updating (Variable target condition) or no updating (Fixed target condition) of target identity, with updating activity estimated by condition comparison. RESULTS: Normal updating activity using this paradigm involved bilateral activation of the dorsolateral prefrontal cortex (DLPFC) and inferior parietal lobe. The PTSD group lacked this activation in the left hemisphere and was significantly different from control subjects in this regard, but showed additional activation in the superior parietal lobe, bilaterally. CONCLUSIONS: The pattern of parietal activation suggests a dependence on visuospatial coding for working memory representation of trauma-neutral, verbal information. Group differences in the relative involvement of the DLPFC indicate less dependence in PTSD on the executive role normally attributed to the left DLPFC for monitoring and manipulation of working memory content in posterior regions of the brain.

Female↗
PubMed2003

Prevalence of psychiatric disorder following the 1988 Yun Nan (China) earthquake--the first 5-month period.

BACKGROUND: There is a continuing need to examine the psychiatric impact of natural disasters for the development of an understanding of the determinants of morbid outcomes. The study of culturally distinct groups provides evidence as to the robustness of psychopathology emerging in the context of traumatic exposures. METHOD: In this study, 1294 people were examined at 5 months after the 1988 Yun Nan earthquake in order to explore the psychiatric impact of this disaster. They were assessed with a number of instruments, including the General Health Questionnaire (28-item version), the Life Event Inventory, and the Post-traumatic Stress Disorder section of the Diagnostic Interview Schedule. Three groups were examined according to their distance from the epicenter of the quake. Their responses were compared with an additional sample of 908 people from a general population living 520 kilometers away from the epicenter. RESULTS: GHQ 'caseness' in the three disaster groups, from those closest to those more distant from the epicenter, were 60.4, 48.2 and 44.0%. These rates were significantly higher than the non-exposed control group (36.2). Among the three disaster groups, taking those who achieved GHQ 'caseness' criteria, the PTSD prevalence was 23, 13 and 16%, respectively. For the overall population experiencing the earthquake (the combined disaster group), a conservative estimate of disaster-related PTSD prevalence was 8.9%. CONCLUSION: The varied rate of morbidity (both general and PTSD-specific) could be attributed to the relative impact of the earthquake as represented by epicenter proximity and as measured by the rate of property damage and loss in the three earthquake-affected areas.

Adolescent↗
PubMed2003

Posttraumatic stress disorder and its impact on the economic and health costs of motor vehicle accidents in South australia.

BACKGROUND: Motor vehicle accident studies thus far have focused primarily on psychiatric consequences and outcomes and medicolegal and treatment aspects, particularly of posttraumatic stress disorder (PTSD). This study aimed to determine the impact of motor vehicle accident-related psychiatric disorders on health and economic costs in quantitative terms. METHOD: Of the 3088 victims of motor vehicle accidents who made a claim through the State Insurance Commission, South Australia, between November 27, 1996, and March 23, 1999, 391 responded to the study and were assessed using the 28-item General Health Questionnaire, the PTSD Checklist-Civilian Version, and the Dissociative Experiences Scale. At the end of the study period, computerized cost records and accounting data on the health and economic costs incurred were obtained for each of the subjects. RESULTS: The total health and economic cost in Australian dollars for the 391 motor vehicle accident victims was A$6,369,519.52. At about 9 months after the accident, of the 391 subjects who replied to the questionnaires, 31% were identified as depressed and 62% as anxious, while 29% met criteria for PTSD. PTSD cases incurred significantly higher health care costs compared with non-PTSD cases (p <.001). Untreated PTSD cases incurred significantly higher economic losses compared with treated PTSD and non-PTSD cases (p <.05). CONCLUSION: The health and economic costs associated with motor vehicle accidents are enormous. Psychiatric morbidity among victims was high, and motor vehicle accident-related PTSD significantly contributed to increased overall health care and economic costs.

Accidents, Traffic↗
PubMed2002

Howard Florey, Alexander Fleming and the fairy tale of penicillin.

The public myth of the discovery of penicillin is an archetypal "quest story" of the type common to every human culture. But the real story of the discovery, testing and refinement of penicillin is a complex tale of accident, serendipity, oversight, conflict, the pressure of war, idiosyncratic personalities and even--the invention of history.

Australia↗
PubMed2002

Abnormal functional connectivity in posttraumatic stress disorder.

This study investigated the efficacy of a combined multivariate/resampling procedure for the analysis of PET activation studies. The covariance-based multivariate analysis was used to investigate distributed brain systems in posttraumatic stress disorder (PTSD) patients and matched controls during performance of a working memory task. The results were compared to univariate results obtained in an earlier study. We also examined whether the PTSD patients demonstrated a breakdown in functional connectivity that may be associated with working memory difficulties often experienced by these patients. A resampling procedure was used specifically to test the reliability of measured between-group effects, to avoid mistaken inference on the basis of random intersubject differences. Significant and reproducible differences in network connectivity were obtained for the two groups. The functional connectivity pattern of the patient group was characterized by relatively more activation in the bilateral inferior parietal lobes and the left precentral gyrus than the control group, and less activation in the inferior medial frontal lobe, bilateral middle frontal gyri and right inferior temporal gyrus. The resampling procedure provided direct evidence that working memory updating was abnormal in PTSD patients relative to matched controls. This work focuses on the need to identify extended brain networks (in addition to regionally specific changes) for the full characterization of brain responses in neuroimaging experiments. Our multivariate analysis explicitly measures the reliability of the patterns of functional connectivity we obtain and demonstrates the potential of such analyses for the study of brain network dysfunction in psychopathology.

Adult↗
PubMed2002

Biologic models of traumatic memories and post-traumatic stress disorder. The role of neural networks.

Neural networks and their behavior provide an information-processing model for initiation and maintenance of the biologic aspects of post-traumatic stress disorder (PTSD). The repeated replaying of the intrusive and distressing recollections that follow a trauma modifies the structure of the neural networks involved in the processing of traumatic memories. The hypothesis is proposed that this repetition instigates the mechanisms of iterative learning, top-down activation and pruning. The development of the symptoms of PTSD can be explained by current knowledge about modeling disturbances of parallel distributing processing. The noradrenergic neurons play a central role in coordinating the interaction of multiple cortical regions, which is an essential aspect of parallel distributed processing. Disturbances of this system in PTSD are likely to be manifest as a dysfunctional modulation of working memory and involuntary traumatic recollection. Modifications of neural networks have a secondary effect of kindling in the hippocampus that further moderates the individual's sensitivity to a range of stressors. Therefore, a neural network model of PTSD provides a method for conceptualizing the onset of PTSD symptoms and their subsequent modification with the passage of time.

Animals↗