Cognitive control training for treatment resistant depression: application, evaluation and augmentation

INTERVENTION: This study is trialling a new behavioural therapy called Cognitive Control Training (CCT). CCT involves repeated practice of targeted cognitive activities that are specifically designed to activate areas of the brain that allow us to control and direct our attention. This study is additionally investigating whether the effectiveness of CCT can be further enhanced using a form of mild brain stimulation called transcranial direct current stimulation (tDCS). tDCS is a safe, non‐invasive, painless technique which has the capacity to temporarily alter cortical excitability. In this study it is delivered to the dorsolateral prefrontal cortex. Participants will be randomised to one of the following four conditions and receive a 25 minute intervention session on fifteen consecutive week days: (a) 25‐minutes of CCT and active tDCS (2 mA) (b) 25‐minutes of CCT and sham tDCS (tDCS that we believe will have no effect) (c) 25‐minutes of a different cognitive training and active tDCS (2 mA) (d) 25‐minutes of a different cognitive training and sham tDCS Stimulation and cognitive training are administered simultaneously. They will be administered by a trained research staff member. Participants will not be informed which condition they have been allocated to until the end of the study. CONDITION: Major depression PRIMARY OUTCOME: The Montgomery Asberg Depression Rating Scale will be used as a primary outcome measure for depression severity. SECONDARY OUTCOME: The 2‐back working memory task will be used as a secondary outcome measure of cognitive control. INCLUSION CRITERIA: 1. Are voluntary and able to provide full informed consent, 2. Are currently in the midst of a Major Depressive Episode as confirmed by structured diagnostic interview with the Mini‐International Interview for DSM‐IV, 3. Are between the ages of 18 and 65 years.