Efficacy of a video‐viewing intervention of smartphone‐based positive word stimulation on depressive symptoms in individuals with subthreshold depression: Protocol for a randomized controlled trial. - Uchida, Hiroyuki; Igusa, Takumi; Machida, Chihaya; Shimada, Tomohiro; Hirao, Kazuki (Psychiatry & Clinical Neurosciences Reports, 2026)