What this Trial Is About

Bipolar depression is a long-lasting and disabling condition, and many people continue to experience depressive symptoms despite standard treatments. Transcranial direct current stimulation (tDCS) is a non-invasive form of brain stimulation that uses a very small electrical current applied through the scalp and has shown promise as a treatment for depression. This study aims to find out whether a home-based tDCS device is effective and safe in reducing symptoms of bipolar depression when compared with a placebo (sham) treatment. The study will also look at how acceptable the treatment is to participants and how well people are able to use the device at home. Who can participate? Adult patients aged 18 years and over who have a diagnosis of bipolar disorder and are currently experiencing a depressive episode. What does the study involve? Participants must meet specific eligibility criteria, which will be assessed by the research team. People who do not meet the study criteria or for whom tDCS is not suitable will not be able to take part. Participants will be randomly assigned to receive either active tDCS or a placebo (sham) treatment. Neither the participant nor the researchers assessing outcomes will know which treatment has been assigned. Participants will use a study device at home over a defined treatment period and will complete a series of assessments at set time points. These include clinician-rated interviews and self-reported questionnaires about mood and well-being. Device use and adherence data will be collected electronically. Participants will also be monitored for any side effects throughout their involvement in the study. Although the study is multi-site, participation is primarily remote, with most study activities completed from the participant's home. What are the possible benefits and risks of participating? Participants may experience an improvement in depressive symptoms. Information gained from this study may help improve future treatments for bipolar depression. tDCS is generally well tolerated. Possible side effects include mild and temporary sensations such as tingling, itching, headache, or skin irritation at the electrode sites. All participants will be monitored for adverse events, and appropriate support will be available if needed. Where is the study run from? The study is run from King's College London in collaboration with NHS research sites across the UK. When is the study starting and how long is it expected to run for? April 2026 to October 2027 Who is funding the study? The National Institute for Health and Care Research (NIHR), UK. Who is the main contact? Professor Cynthia Fu, the Chief Investigator at King's College London, cynthia.fu@kcl.ac.uk

A Study of Home-use Brain Stimulation to Treat Bipolar Depression