Several large-scale cohort studies have focused on the mental health of residents affected by the Great East Japan Earthquake (GEJE), but no study has clarified details of the long-term course of mental health after the disaster. Therefore, the present study investigated the long-term trajectories of psychological distress among residents of GEJE-affected areas using data from an annual cohort survey conducted over a 10-year period after the disaster. We used data from a community-based cohort study included in the Shichigahama Health Promotion Project for residents of the town of Shichigahama, Miyagi Prefecture, which was affected by the GEJE. Included in the analysis were 1,083 subjects aged ≥20 years at the time of the first survey and who had responded at least five times between 2011 and 2020, including the first survey. Psychological distress was evaluated using the K6 scale. Group-based trajectory modeling revealed the following four-trajectory model characterized by longitudinal alterations in psychological distress: resistant trajectory (n=275,25.4%), subthreshold trajectory (n=455,42.0%), moderately affected trajectory (n=291,26.9%), and severely affected trajectory (n=62,5.7%) (BIC=-25,159.5, log Bayes factor=309.4).
 The overall psychological distress alterations showed a tendency to decrease gradually and suggested that the degree of psychological distress in the early phase of the disaster was maintained over a long time. Therefore, it is necessary to provide long-term, focused support to those who experience severe psychological distress in the early phase of a disaster.
 Authors' abstract