Abstract
BackgroundAntipsychotic 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 (ABM) training 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. Second, the study will assess the preliminary efficacy of ABM + tDCS in reducing food cravings in people who take antipsychotic medication.MethodsThirty adults with a DSM-V diagnosis of schizophrenia or schizoaffective disorder treated with anti-psychotic medication will be randomly allocated to receive five 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).DiscussionThe 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.Trial registrationISRCTN Registry, ISRCTN13280178. Registered on 16 October 2018.
Highlights
Antipsychotic drug-induced weight gain puts individuals with schizophrenia at increased cardiometabolic risk
Antipsychotic drug-induced weight gain can affect the physical health of people with schizophrenia
Interventions to prevent weight gain have limited effectiveness in acutely unwell patients who may find it hard to engage in diet or exercise behaviours [7]
Summary
Design This is a parallel group, double-blind, two-arm RCT. Participants will be randomly allocated to receive five sessions of either ABM + real tDCS (treatment group) or ABM + sham tDCS (control group) over 3–4 weeks, delivered in addition to treatment as usual. Other clinical outcomes (1) Questionnaires assessing: depression - Depression, Anxiety and Stress Scale (DASS-21) [61], cognitive deficits - Montreal Cognitive Assessment (MoCA) [62], and impulsivity - Barratt Impulsiveness Scale (BIS-11) [63] will be administered at baseline and (1) Acceptability of the intervention will be measured as follows: (a) before and after each treatment session by collecting VAS scores on the levels of tension, stress and anxiety; (b) before and after each treatment session by asking about any comments about the treatment; (c) at the end of the study, by asking participants if they would like to take part in a therapeutic trial of tDCS if this was available; and (d) by the number of recruited participants. Analyses Feasibility The decision as to whether to progress the study to a future large-scale RCT will be based on a number of criteria These include the number of patients we are able to recruit, the proportion of patients retained, the proportion of patients completing the real and sham ABM + tDCS intervention, the acceptability and tolerability of the tDCS and the effect sizes of treatment outcomes.
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