The mechanisms and effects of modifying attentional biases to threatening information

Patients with both depression and anxiety show an increased tendency to deploy attention towards negative information. Cognitive models of the illnesses predict that these negative attentional biases are causally related to the symptoms of the disorders. Consistent with this, modifying attentional bias using either antidepressant medication or simple, computer based training tasks has previously been associated with altered symptomatology in both non-clinical and clinical populations. The current thesis aimed to investigate the mechanisms by which attentional bias training tasks alter attention. The investigations were conducted within an experimental neuroscience framework which has previously been successfully deployed in studies of antidepressant medication. The thesis then sought to use these initial results to improve the basic understanding of attentional control processes and, ultimately, guide the development of novel treatment strategies. The initial studies of the thesis characterised the behavioural and neural effects of attentional bias training. Behaviourally, a high degree of generalisation of the training effect was found across a range of emotional stimuli. Neurally, training was found to alter activity in a network of prefrontal regions known to be involved in the control of attention. Further analysis, utilising a computational learning model, suggested that the attentional control systems identified in this study could be understood in terms of expectation based processes. These studies therefore indicated that, in contrast to the predominately limbic effects of antidepressant medication, training initially altered the response of frontal control circuitry. The later studies of the thesis investigated possible strategies for extending the use of attentional bias training. Firstly, combining training with antidepressant medication was found to produce an interference effect on emotional memory suggesting that administering both interventions concurrently is likely to erode their cognitive impact. Lastly, attentional bias training was found not to alter attention in patients with bipolar disorder, with the results of the study indicating that standard assessments of attentional bias in this clinical population are likely to be unreliable. Overall, these studies indicate that attentional bias training may be used to alter the top-down control of attention to emotional information and suggest that such effects may interfere with the bottom-up effects of antidepressant drugs. More generally the work demonstrates the utility of using a cognitive-neuroscientific framework to explore the mechanisms and impact of novel therapeutic strategies.This thesis is not currently available via ORA