Effects of Transcranial Direct Current Stimulation (tDCS) and Approach Bias Modification training (ABM) on food cravings in people taking antipsychotic medication

Abstract

Background Antipsychotic drug induced weight gain puts individuals with schizophrenia at increased cardiometabolic risk. As a potential intervention for this problem we describe the theoretical background and a protocol for a feasibility randomised controlled trial (RCT) of approach bias modification training (ABM) combined with real versus sham (placebo) transcranial direct current stimulation (tDCS). The primary aim of this trial is to obtain information that will guide decision making and protocol development in relation to a future large-scale RCT of ABM and tDCS in this group of participants. Secondly, the study will assess the preliminary efficacy of [ABM + tDCS] in reducing food cravings in people who take antipsychotic medication. Methods Thirty adults with a DSM-V diagnosis of schizophrenia or schizoaffective disorder treated with anti-psychotic medication will be randomly allocated to receive 5 sessions that will combine ABM and real or sham tDCS, in a parallel group design. In this feasibility study a broad range of outcome variables will be examined. Measures will include food craving, psychopathology (e.g. symptoms of schizophrenia and depression), neuropsychological processes (such as attentional bias, and impulsiveness) and the tolerability and acceptability of tDCS. The feasibility of conducting a large-scale RCT of [ABM + tDCS] and appropriateness of tDCS as a treatment for antipsychotic drug induced weight gain will be evaluated by assessment of recruitment and retention rates, acceptability of random allocation, blinding success (allocation concealment), completion of treatment sessions and research assessments (baseline, post-treatment and follow-up). Discussion The effect sizes generated and other findings from this trial will inform a future large-scale RCT with respect to decisions on primary outcome measures and other aspects of protocol development. In addition, results from this study will provide a preliminary indication of the efficacy of [ABM + tDCS] treatment for antipsychotic drug induced weight gain.