Between fact and fantasy : mechanisms and treatment implications of mental imagery in depression

Abstract

While negative and intrusive mental imagery is most commonly associated with posttraumatic stress disorder (PTSD), research findings show it is a transdiagnostic feature present across different psychological disorders. Intrusive imagery is increasingly found to be a phenomenon present in depression, but how it affects depressive disorders is still unknown. Previous studies have focused on different phenomenological properties of imagery such as vividness and frequency, and results have been inconsistent as to which ones are associated with depression. The present research aims to investigate whether intrusive imagery is predictive of depression severity, first by testing which imagery properties are more parsimoniously related to depression as a whole, before investigating avoidance mechanisms that may be underlying their relationship. Based on theories that the abstractevaluative and verbal nature of rumination and worry facilitates avoidance of imagery and emotion, it is argued that such processes may be involved. The first study had a clinical sample of depressive patients undergo a semi-structured interview about their experience of intrusive imagery, as well as complete a battery of questionnaires measuring depressive symptoms, rumination, worry and experiential avoidance. A confirmatory factor analysis tested the factor structure of intrusive imagery, while several mediation models within a structural equation modelling framework investigated possible avoidance processes underlying its relationship with depression. Results not only supported a significant association between intrusive imagery and depression severity, but the mediating role intrusive imagery played in how rumination and worry predicted depression. The experiential avoidance was found to both mediate how rumination and worry predicted depression, as well as predicting depression through intrusive imagery. To further investigate whether targeting intrusive images and the use of imagery processes in treatment would be beneficial to treatment, an imagery-based intervention (imagery rescripting, ImRs) was tested in depression. Comparison with a more commonly used linguistic-based technique (cognitive restructuring, CR) aimed to not only establish the efficacy of ImRs in treating depression, but to assess whether the experiential use of imagery would possibly target the abstract-evaluative, verbal processes of rumination and worry affecting intrusive imagery found in study 1. Results showed that ImRs was equally if not more effective in alleviating depression, demonstrating how it is not logic alone that leads to improvement in mood. Significant differential reductions in the abstract verbal processes of rumination and worry between treatments also add support to the technique’s experiential nature and possibly defusing out of an abstract-evaluative mode of processing. Together, the findings from this research program support the significance of mental imagery in depression, both as a symptom of intrusive imagery in the pathogenesis of depression, as well as its therapeutic potential in the treatment of depression.