Predicting Medication Nonadherence in Older Adults With Difficult-to-Treat Depression in the IRL-GRey Randomized Controlled Trial

•What is the primary question addressed by this study?We examined sociodemographic, clinical, and treatment factors that may predict antidepressant non-adherence during early (weeks 1–6), late (weeks 7–12), and augmentation (weeks 13–24) treatment.•What is the main finding of this study?Poor cognitive function and early response were predictive of early nonadherence. Poor cognitive function and prior nonadherence were predictive of late nonadherence. Living alone was associated with nonadherence both late and during augmentation treatment.•What is the meaning of the finding?Patient education should focus on the natural history and risk of relapse and recurrence of depression if patients stop taking their antidepressant medications early. Future intervention development should consider the role of evaluating cognitive function and providing psychoeducation regarding depression to help with improving medication adherence, particularly among older adults who live alone.