Light and Ion Maintenance In Treatment for Depression (LIMIT-D): Feasibility Study

The purpose of this study is to evaluate the feasibility of a multicentre, randomized, trial of light therapy and negative ion therapy as substitutes for antidepressants for maintenance treatment for patients with recurrent major depressive disorder (MDD). The study design for this feasibility study mirrors the full LIMIT-D protocol: a 28-week, double-blind (participant and outcome rater) relapse prevention study with 100 participants randomized 1:1 to one of two study treatments, light therapy or negative ion therapy, and assessed for relapse over 28 weeks. Half the study devices are modified to be inactive. After 2 weeks of study treatment, the participant's antidepressant will be tapered and discontinued between Week 2 and Week 8. Participants are assessed for relapse at each scheduled study visit (every 2 weeks during antidepressant taper until week 8, then every 4 weeks until end of study treatment at Week 28) by blind outcome raters. In addition, they complete an online Personal Health Questionnaire (PHQ-9) self-rated depression symptom scale bi-weekly; if total score is 10 or higher OR the suicide item score is 2 or higher, participants are booked for a relapse-assessment visit and relapse-verification study visit at least 1 week apart. Relapse will be defined as any of the following: 1. MADRS total score 20 or higher for at least 2 consecutive weeks and Diagnostic and Statistical Manual (DSM-5) criteria for major depressive episode at the Relapse-Verification visit. 2. Hospitalization for worsening of depression. 3. Suicidal ideation with intent or plan, or suicidal behaviour. 4. Any change in treatment for depression (e.g., starting an antidepressant). At each visit, clinician-rated and self-rated symptom, side effect, and functioning measures are completed. The primary feasibility outcome is recruitment rate; secondary feasibility outcomes include adherence to study treatment, successful discontinuation of antidepressants rate, and all-cause dropout rate. Secondary clinical outcomes include relapse rate, time to relapse, adverse events, and safety profiles. Participants will wear an actigraph at home during the 28-week study treatment period to assess sleep, light and activity/circadian rhythms. There is a final observational visit by Zoom videoconference at Week 52.