Biomedical subjects

Richard A Bryant

Publications and source records attributed to Richard A Bryant.

At least 19 recordsLinked to original sources

PubMed2006

Keeping memories at an arm's length: vantage point of trauma memories.

This study investigated the relationship between memory vantage point and avoidance following trauma. Sixty trauma survivors with differing levels of avoidance were interviewed about the vantage point of their memory for trauma, a positive memory, and a neutral memory. Avoidant individuals were more likely to remember their trauma from an observer perspective than individuals with a lower level of avoidance. Avoidance did not influence vantage point for positive or neutral memories. These data support the proposal that adoption of the observer vantage point for trauma memories may serve an avoidant function for people affected by trauma.

Adolescent↗

PubMed2006

Does dissociation further our understanding of PTSD?

Peritraumatic dissociation, and other dissociative reactions, refer to alterations in awareness in the context of a traumatic experience. This review provides an overview of the current conceptualization of dissociation, critiques methodological approaches to studying dissociation, and reviews the evidence for the purported relationship between dissociative reactions and posttraumatic stress disorder. The evidence challenges the notion that a linear relationship exists between dissociation and psychiatric morbidity. Future research should abandon the global construct of dissociation, and study the specific responses that involve altered awareness under experimental conditions.

Acute Disease↗

PubMed2006

How time flies: a study of novice skydivers.

Although time distortion is commonly reported during a traumatic experience, there is little research addressing the phenomenon. This study investigated the role of affect in time perception in a very stressful experience by indexing novice tandem skydivers' (N=76) levels of fear and excitement before the skydive and soon after landing. Estimations of how long skydivers thought their experience lasted were obtained after landing. Whereas increased fear was associated with the perception of time passing slowly, increased excitement was associated with the perception of time passing quickly. These data support models of time perception based on avoidance and approach motivations influencing time distortion.

Adolescent↗

PubMed2006

The tendency to suppress, inhibiting thoughts, and dream rebound.

Ironic control theory proposes that suppressing thoughts leads to increased occurrence of the suppressed thought because monitoring for the unwanted thought leads to intrusions. This study investigated the influence of suppressing unwanted thoughts on dream content. One hundred participants who had high or low levels of tendency to suppress unwanted thoughts nominated an intrusive thought, and half of the participants were instructed to suppress that thought for 5 min prior to sleeping. Participants completed a dream diary upon waking, which was subsequently rated by independent raters for dream content. In terms of the 79 participants who reported dreaming, more high suppressors who were instructed to suppress dreamt about the intrusive thought than high suppressors in the control condition. There was no difference between low suppressors in the suppression and control conditions. These results suggest that dream content can be influenced by attempted suppression prior to sleep, and this is particularly apparent in people with a tendency to suppress unwanted thoughts.

Adult↗

PubMed2006

Amygdala-prefrontal dissociation of subliminal and supraliminal fear.

Facial expressions of fear are universally recognized signals of potential threat. Humans may have evolved specialized neural systems for responding to fear in the absence of conscious stimulus detection. We used functional neuroimaging to establish whether the amygdala and the medial prefrontal regions to which it projects are engaged by subliminal fearful faces and whether responses to subliminal fear are distinguished from those to supraliminal fear. We also examined the time course of amygdala-medial prefrontal responses to supraliminal and subliminal fear. Stimuli were fearful and neutral baseline faces, presented under subliminal (16.7 ms and masked) or supraliminal (500 ms) conditions. Skin conductance responses (SCRs) were recorded simultaneously as an objective index of fear perception. SPM2 was used to undertake search region-of-interest (ROI) analyses for the amygdala and medial prefrontal (including anterior cingulate) cortex, and complementary whole-brain analyses. Time series data were extracted from ROIs to examine activity across early versus late phases of the experiment. SCRs and amygdala activity were enhanced in response to both subliminal and supraliminal fear perception. Time series analysis showed a trend toward greater right amygdala responses to subliminal fear, but left-sided responses to supraliminal fear. Cortically, subliminal fear was distinguished by right ventral anterior cingulate activity and supraliminal fear by dorsal anterior cingulate and medial prefrontal activity. Although subcortical amygdala activity was relatively persistent for subliminal fear, supraliminal fear showed more sustained cortical activity. The findings suggest that preverbal processing of fear may occur via a direct rostral-ventral amygdala pathway without the need for conscious surveillance, whereas elaboration of consciously attended signals of fear may rely on higher-order processing within a dorsal cortico-amygdala pathway.

Adult↗

PubMed2006

Hypnotically induced emotional numbing: the roles of hypnosis and hypnotizability.

This study investigated the roles of hypnotizability and hypnosis in suggested emotional numbing. Thirty-two high hypnotizable and 32 low hypnotizable participants were administered either a hypnotic or wake induction and were then presented with emotionally distressing and neutral images during a suggestion for emotional numbing or a control condition. Emotional response was indexed through self-report and EMG corrugator-muscle activity. High hypnotizable participants, in both the hypnosis and wake conditions, reported more diminished emotional responses on self-report and EMG corrugator-muscle activity than low hypnotizable participants during the emotional-numbing suggestion. These findings suggest that elevated hypnotic susceptibility, rather than hypnosis, is an important mediator of emotional numbing. The importance of individual differences in emotional numbing is discussed.

Adult↗

PubMed2006

Hypnotic conflict: a brief report.

Two studies investigated management of conflict in hypnosis by subtly increasing the brightness of a visual stimulus during a suggestion for hypnotic blindness to the stimulus. In Study 1, 23 high hypnotizable participants were administered a hypnotic suggestion for blindness to a projected light. For half the participants, the brightness of the light was intensified during the suggestion. Behavioral ratings and online analog-dial measurement indicated that participants reported decreased hypnotic blindness during the increased conflict condition. In Study 2, 20 participants were administered the nonexperimental procedure to investigate the impact of demand characteristics in this paradigm. Parallel findings in Studies 1 and 2 indicated that demand characteristics may explain the response to hypnotic conflict. Limitations in applying the nonexperimental procedure to this paradigm and the need for further investigation are discussed.

Adult↗

PubMed2006

Enhancing thought suppression with hypnosis.

Much research indicates that attempts to suppress thoughts lead to increased accessibility of those thoughts, especially when additional cognitive load is present. On the premise that hypnosis may permit more effective management of cognitive load, it was hypothesized that hypnosis may enhance more effective thought suppression. The present research examined whether the obstacle of cognitive load could be bypassed using hypnosis to facilitate successful thought suppression. Thirty-nine high and 40 low hypnotizable participants were hypnotized and received either a suppression instruction or no instruction for a memory of an embarrassing experience and subsequently completed a sentence-unscrambling task that indexed accessibility of embarrassing thoughts. Whereas lows instructed to suppress displayed a delayed increase in suppressed thoughts, highs did not. These findings support the proposition that hypnosis facilitates thought suppression.

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

Predicting severity of non-clinical depression: preliminary findings using an integrated approach.

INTRODUCTION: Depression is characterized by disturbances in affect, cognition, brain and body function, yet studies have tended to focus on single domains of dysfunction. An integrated approach may provide a more complete profile of the range of deficits characterized by depressed individuals, but it is unclear whether this approach is able to predict depression severity over and above that predicted by single tasks or domains of function. In this study, we examined the value of combining multiple domains of function in predicting depression severity. METHODS: Participants contained in the International Brain Database, (http://www.brainresource.com) had completed three testing components including a web-based questionnaire of Personal History, the Brain Resource Cognition battery of Neuropsychological tests, Personality assessment and Psychophysiological testing. Two hundred and sixty six of these participants were able to be classified as either non-depressed, mild-moderately or severely (non-clinically) depressed, based on a depression screening questionnaire. Analysis of variance identified variables on which the categorized participants differed. Significant variables were then entered into a series of stepwise regressions to examine their ability to predict depression scores. RESULTS: An integrated model including measures of affect (increased Neuroticism; decreased Emotional Intelligence), cognition (increased variability of reaction time during a working memory task; decreased "name the word component score" in the verbal interference task), brain (decreased left-lateralized P150 ERP component during a working memory task) and body function (increased negative skin conductance level gradient) were found to predict more of the variation in depression severity than any single domain of function. DISCUSSION: On the basis of behavioral as well as Psychophysiological findings reported in this study, it was suggested that deficits in subclinically depressed individuals are more pronounced during automatic stages of stimulus processing, and that performance in these individuals may improve (to the level displayed by controls) when task demands are increased. Findings also suggest that it is important to consider disturbances across different domains of function in order to elucidate depression severity. Each domain may contribute unique explanatory information consistent with an integrative model of depression, taking into account the role of both behavior and underlying neural changes.

Acoustic Stimulation↗

PubMed2006

Longitudinal psychophysiological studies of heart rate: mediating effects and implications for treatment.

Fear conditioning models of posttraumatic stress disorder (PTSD) propose that noradrenergic activation at the time of trauma leads to over-consolidation of trauma memories and contributes to PTSD. This model suggests that resting heart rate (HR) in the acute phase after trauma may reflect the strength of the noradrenergic response and may represent an initial marker of those who are at risk of PTSD development. Ten prospective studies are reported that assessed the relationship of resting HR within 1 week of trauma and subsequent PTSD. Whereas 8 of the 10 studies found that elevated HR in the acute phase was associated with increased risk of subsequent PTSD, there was much variability in the HR levels and subsequent PTSD. The current data suggest multiple pathways to PTSD development that may not necessarily involve elevated HR. The data indicate that HR in the acute phase cannot be accurately used to identify people who are at risk for PTSD. The association between HR and PTSD does suggest that HR is a useful means to test fear conditioning models of trauma response.

Biomarkers↗

PubMed2006

Intrusive experiences and hyperarousal in acute stress disorder.

OBJECTIVE: This study investigated the relationship between hyperarousal, intrusions, and dissociative experiences in acute stress disorder (ASD). METHOD: Trauma survivors with ASD (n=30) and without ASD (n=30) completed either a hyperventilation provocation test (HVPT) or a non-hyperventilating control procedure whilst monitoring intrusive experiences. Participants then completed the Physical Reactions Scale and the Peritraumatic Dissociative Experiences Questionnaire. RESULTS: Whereas the hyperventilation procedure resulted in an increase in the number of intrusions for ASD participants, the hyperventilation procedure resulted in a decrease in the number of intrusions for non-ASD participants. Contrary to expectations, there was no differences in dissociative reactions across group or condition. CONCLUSIONS: These findings provide evidence that intrusive phenomenon are directly associated with elevated states of arousal for individuals with ASD.

Adult↗

PubMed2006

Early life stress and adult emotional experience: an international perspective.

Early life stress (ELS) has been linked to adult psychopathology, though few studies have examined the universality of specific adverse childhood events (ACEs) in healthy adults. We examined the co-occurrence of specific ACEs and their relationship to current emotional distress in an international sample of adults without psychopathology. Participants were 1659 men and women recruited for an international neurocognitive-neuroimaging database from sites in the United States, Australia, England, and the Netherlands. Participants had no current or prior diagnosis of major depression, anxiety, substance abuse, or neurological brain disorder. The occurrence and age on onset of 19 ACEs was assessed by a self-report questionnaire (ELSQ), and current symptoms of stress, depression, and anxiety by the Depression Anxiety Stress Scale (DASS). The relationship of specific ACEs to DASS symptoms was examined. Participants reported relatively high prevalence of ACEs. Only 27.6% of the sample reported no ACEs, while 39.5% reported one or two significant experiences and 32.9% reported more than two ACEs. Rates of most ACEs were quite similar across the three continents. Various ACEs were significantly associated with current DASS severity, particularly ACEs involving emotional abuse, neglect, and family conflict, violence, and breakup. Finding nearly one-third of the sample reported three or more ACEs suggest a high prevalence of ELS in otherwise healthy "normal" adults around the world. Associations between ELS and current emotional distress suggest that these events have functional relevance and deserve further investigation.

Adult↗

PubMed2006

Recovery after the tsunami: timeline for rehabilitation.

In the aftermath of the Asian tsunami, there is potentially a large, traumatized population in need of psychosocial support, but determining which individuals require psychological intervention and knowing how and when to treat them may be the key to positive long-term outcomes. The early identification of people at high risk of developing subsequent psychiatric disorders from among those experiencing a transient stress reaction following trauma is often the initial step in the recovery process. Clinical instruments for screening and/or predicting those most at risk are available and require validating for cultural and linguistic sensitivity. Timely treatment is essential, since inappropriately targeted therapy can compromise recovery and may even exacerbate posttraumatic stress symptoms, particularly if treatment is initiated before grief reactions have subsided. Finally, appropriate treatment interventions, which incorporate cognitive-behavioral therapy and prolonged exposure, offer the best current therapeutic options for the treatment of posttraumatic stress disorder and associated comorbid conditions such as anxiety, depression, and grief. However, since most of the supportive data for the psychosocial consequences of trauma were obtained from small-scale studies of discrete trauma events in Western countries, it may not be possible to extrapolate these findings to a large-scale natural disaster in Asia, such as the Asian tsunami. More data are required to assist in the development of strategies for the effective management of the psychological consequences of trauma worldwide, with emphasis on creating mental health strategies that are culturally sensitive and valid for various trauma events and disaster scenarios.

Anxiety Disorders↗

PubMed2006

Cultural sensitivity: making trauma assessment and treatment plans culturally relevant.

The Asian tsunami on December 26, 2004, has had a profound impact on the mental health of large numbers of people in several South Asian nations. Many psychological interventions with relevance to this disaster have been shown to be effective in a Western context. For these psychological interventions to prove effective in the tsunami-affected regions, they must be understood and accepted by health-care practitioners and patients in their individual cultural settings and must be adapted to these settings on the basis of careful dialogue between health-care professionals, community and religious leaders, and patients. Religious, socioeconomic, and other cultural influences all affect the acceptability and success of various psychological assessment and treatment tools. The cultural specificity of these tools needs careful validation in the tsunami-affected countries. The challenge in each local situation is to find the optimal means of adapting tools such as cognitive-behavioral therapy into appropriate strategies for local communities. We advocate a culturally sensitive approach to ensure that the impact of interventions is optimized to benefit the communities recovering from such a traumatic disaster.

Asia↗

PubMed2005

Hypnotherapy and cognitive behaviour therapy of acute stress disorder: a 3-year follow-up.

The long-term benefits of cognitive behaviour therapy (CBT) for trauma survivors with acute stress disorder were investigated by assessing patients 3 years after treatment. Civilian trauma survivors (n=87) were randomly allocated to six sessions of CBT, CBT combined with hypnosis, or supportive counselling (SC), 69 completed treatment, and 53 were assessed 2 years post-treatment for post-traumatic stress disorder (PTSD) with the Clinician-Administered PTSD Scale. In terms of treatment completers, 2 CBT patients (10%), 4 CBT/hypnosis patients (22%), and 10 SC patients (63%) met PTSD criteria at 2-years follow-up. Intent-to-treat analyses indicated that 12 CBT patients (36%), 14 CBT/hypnosis patients (46%), and 16 SC patients (67%) met PTSD criteria at 2-year follow-up. Patients who received CBT and CBT/hypnosis reported less re-experiencing and less avoidance symptoms than patients who received SC. These findings point to the long-term benefits of early provision of CBT in the initial month after trauma.

Adolescent↗

PubMed2005

Trauma modulates amygdala and medial prefrontal responses to consciously attended fear.

Effective fear processing relies on the amygdala and medial prefrontal cortex (MPFC). Post-trauma reactions provide a compelling model for examining how the heightened experience of fear impacts these systems. Post-traumatic stress disorder (PTSD) has been associated with excessive amygdala and a lack of MPFC activity in response to nonconscious facial signals of fear, but responses to consciously processed facial fear stimuli have not been examined. We used functional MRI to elucidate the effect of trauma reactions on amygdala-MPFC function during an overt fear perception task. Subjects with PTSD (n = 13) and matched non-traumatized healthy subjects (n = 13) viewed 15 blocks of eight fearful face stimuli alternating pseudorandomly with 15 blocks of neutral faces (stimulus duration 500 ms; ISI 767 ms). We used random effects analyses in SPM2 to examine within- and between-group differences in the MPFC and amygdala search regions of interest. Time series data were used to examine amygdala-MPFC associations and changes across the first (Early) versus second (Late) phases of the experiment. Relative to non-traumatized subjects, PTSD subjects showed a marked bilateral reduction in MPFC activity (in particular, right anterior cingulate cortex, ACC), which showed a different Early-Late pattern to non-traumatized subjects and was more pronounced with greater trauma impact and symptomatology. PTSD subjects also showed a small but significant enhancement in left amygdala activity, most apparent during the Late phase, but reduction in Early right amygdala response. Over the time course, trauma was related to a distinct pattern of ACC and amygdala connections. The findings suggest that major life trauma may disrupt the normal pattern of medial prefrontal and amygdala regulation.

Adult↗

PubMed2005

Distinct amygdala-autonomic arousal profiles in response to fear signals in healthy males and females.

The amygdala has a key role in regulating arousal and vigilance, and responds to both visual and vocal signals of fear, including facial expressions of fear. In this study, we used functional MRI to examine sex differences in the magnitude, extent, lateralization and time course of amygdala responses to facial signals of fear, in a relatively large sample of males and females. Skin conductance was recorded simultaneously with functional imaging to examine concomitant changes in emotional arousal, and to provide an independent index of response attenuation. Scanning and skin conductance recording was undertaken during perception of facial fear stimuli. Sex differences were apparent in the laterality and time course of fear perception. In males, the right amygdala and autonomic arousal attenuated over the late half of the experiment. By contrast, females showed persistent bilateral amygdala responses, with a tendency towards greater left amygdala engagement during the late phase. Females also showed a greater general extent of amygdala response. We suggest that distinct evolutionary pressures might contribute to a lower threshold for vigilance to signals of danger in females, reflected in a profile of sustained amygdala-arousal interaction.

Adult↗