Corin Bourne

Inducing and modulating intrusive emotional memories: a review of the trauma film paradigm.

Highly affect-laden memory intrusions are a feature of several psychological disorders with intrusive images of trauma especially associated with post-traumatic stress disorder (PTSD). The trauma film paradigm provides a prospective experimental tool for investigating analogue peri-traumatic cognitive mechanisms underlying intrusion development. We review several historical papers and some more recent key studies that have used the trauma film paradigm. A heuristic diagram is presented, designed to simplify predictions about analogue peri-traumatic processing and intrusion development, which can also be related to the processing elements of recent cognitive models of PTSD. Results show intrusions can be induced in the laboratory and their frequency amplified/attenuated in line with predictions. Successful manipulations include competing task type (visuospatial vs. verbal) and use of a cognitive coping strategy. Studies show that spontaneous peri-traumatic dissociation also affects intrusion frequency although attempts to manipulate dissociation have failed. It is hoped that further use of this paradigm may lead to prophylactic training for at risk groups and an improved understanding of intrusions across psychopathologies.

Neuropsychological testing of cognitive impairment in euthymic bipolar disorder: an individual patient data meta-analysis.

An association between bipolar disorder and cognitive impairment has repeatedly been described, even for euthymic patients. Findings are inconsistent both across primary studies and previous meta‐analyses. This study reanalysed 31 primary data sets as a single large sample (N = 2876) to provide a more definitive view.

Subcortical volumetric abnormalities in bipolar disorder.

Considerable uncertainty exists about the defining brain changes associated with bipolar disorder (BD). Understanding and quantifying the sources of uncertainty can help generate novel clinical hypotheses about etiology and assist in the development of biomarkers for indexing disease progression and prognosis. Here we were interested in quantifying case–control differences in intracranial volume (ICV) and each of eight subcortical brain measures: nucleus accumbens, amygdala, caudate, hippocampus, globus pallidus, putamen, thalamus, lateral ventricles. In a large study of 1710 BD patients and 2594 healthy controls, we found consistent volumetric reductions in BD patients for mean hippocampus (Cohen’s d=−0.232; P=3.50 × 10−7) and thalamus (d=−0.148; P=4.27 × 10−3) and enlarged lateral ventricles (d=−0.260; P=3.93 × 10−5) in patients. No significant effect of age at illness onset was detected. Stratifying patients based on clinical subtype (BD type I or type II) revealed that BDI patients had significantly larger lateral ventricles and smaller hippocampus and amygdala than controls. However, when comparing BDI and BDII patients directly, we did not detect any significant differences in brain volume. This likely represents similar etiology between BD subtype classifications. Exploratory analyses revealed significantly larger thalamic volumes in patients taking lithium compared with patients not taking lithium. We detected no significant differences between BDII patients and controls in the largest such comparison to date. Findings in this study should be interpreted with caution and with careful consideration of the limitations inherent to meta-analyzed neuroimaging comparisons.

The neural basis of flashback formation: The impact of viewing trauma

Background Psychological traumatic events, such as war or road traffic accidents, are widespread. A small but significant proportion of survivors develop post-traumatic stress disorder (PTSD). Distressing, sensory-based involuntary memories of trauma (henceforth ‘flashbacks’) are the hallmark symptom of PTSD. Understanding the development of flashbacks may aid their prevention. This work is the first to combine the trauma film paradigm (as an experimental analogue for flashback development) with neuroimaging to investigate the neural basis of flashback aetiology. We investigated the hypothesis that involuntary recall of trauma (flashback) is determined during the original event encoding. Method A total of 22 healthy volunteers viewed a traumatic film whilst undergoing functional magnetic resonance imaging (fMRI). They kept a 1-week diary to record flashbacks to specific film scenes. Using a novel prospective fMRI design, we compared brain activation for those film scenes that subsequently induced flashbacks with both non-traumatic control scenes and scenes with traumatic content that did not elicit flashbacks (‘potentials’). Results Encoding of scenes that later caused flashbacks was associated with widespread increases in activation, including in the amygdala, striatum, rostral anterior cingulate cortex, thalamus and ventral occipital cortex. The left inferior frontal gyrus and bilateral middle temporal gyrus also exhibited increased activation but only relative to ‘potentials’. Thus, these latter regions appeared to distinguish between traumatic content that subsequently flashed back and comparable content that did not. Conclusions Results provide the first prospective evidence that the brain behaves differently whilst experiencing emotional events that will subsequently become involuntary memories – flashbacks. Understanding the neural basis of analogue flashback memory formation may aid the development of treatment interventions for this PTSD feature.

Verbal learning impairment in euthymic bipolar disorder: BDI v BDII.

Objectives Cognitive impairment is known to occur in bipolar disorder (BD), even in euthymic patients, with largest effect sizes often seen in Verbal Learning and Memory Tasks (VLT). However, comparisons between BD Type-I and Type-II have produced inconsistent results partly due to low sample sizes. Methods This study compared the performance of 183 BDI with 96 BDII out-patients on an adapted version of the Rey Verbal Learning Task. Gender, age, years of education, mood scores and age at onset were all used as covariates. Current medication and a variety of illness variables were also investigated for potential effects on VLT performance. Results BDI patients were significantly impaired relative to BDII patients on all five VLT outcome measures after controlling for the other variables [Effect Sizes=.13–.17]. The impairments seem to be unrelated to drug treatment and largely unrelated to illness variables, although age of onset affected performance on three outcome measures and number of episodes of mood elevation affected performance on one. Limitations This study used historical healthy controls. Analysis of potential drug effects was limited by insufficient participants not being drug free. Cross-sectional nature of the study limited the analysis of the potential effect of illness variables. Conclusions This study replicates earlier findings of increased verbal learning impairment in BDI patients relative to BDII in a substantially larger sample. Such performance cannot be wholly explained by medication effects or illness variables. Thus, the cognitive impairment is likely to reflect a phenotypic difference between bipolar sub-types.

MVPA to enhance the study of rare cognitive events: An investigation of experimental PTSD

Many cognitive processes are challenging to study due to their scarce occurrence. Here we demonstrate how pattern recognition and brain imaging can enhance the study of such processes by providing fast, sensitive, and non-intrusive detection of these events. This can enable efficient experimental and clinical intervention. We focus on the study of traumatic events producing flashbacks associated with post-traumatic stress disorder (PTSD), using an experimental analogue of trauma (a traumatic film). These events are rare and challenging to reliably elicit in experimental settings. We show that a classifier can be built to predict, based upon brain response, which stimuli are likely to induce these rare flashbacks at the point of exposure. An ability to predict these stimuli makes possible the trialing of context-specific preventative clinical interventions. We present results from two independent datasets, outlining key analytic challenges.

Letter to the Editor: A reply – acknowledged reasonable limitations in a secondary analysis but key conclusions remain in ‘The neural basis of flashback formation: the impact of viewing trauma’

The current letter by Mole (2016) highlights three recent papers from our laboratory that have attempted to investigate how the initial processing of intrusively remembered episodes leads to their formation (Bourne et al. 2013; Clark et al. 2014, 2016). These intrusively remembered episodes are from films with traumatic content. Intrusive memories (referred to as flashbacks in Bourne et al. 2013) are ones which come to mind unbidden, and have particular relevance to post-traumatic stress disorder (PTSD). Mole (2016) suggests that one of the subanalyses performed in Bourne et al. (2013) is methodologically flawed and questions some of our subsequent interpretations. While there are elements of the critique we accept, we would like to refute some of the inferences drawn by Mole (2016). In particular, we argue that the main conclusions of our papers are not affected by the ‘methodological flaw’ raised.

Neuropsychological testing of cognitive impairment in euthymic bipolar disorder

An association between bipolar disorder and cognitive impairment has repeatedly been described, even for euthymic patients. Findings are inconsistent both across primary studies and previous meta‐analyses. This study reanalysed 31 primary data sets as a single large sample (N = 2876) to provide a more definitive view.

Neuropsychological testing of cognitive impairment in euthymic bipolar disorder: an individual patient data meta-analysis

An association between bipolar disorder and cognitive impairment has repeatedly been described, even for euthymic patients. Findings are inconsistent both across primary studies and previous meta‐analyses. This study reanalysed 31 primary data sets as a single large sample (N = 2876) to provide a more definitive view.