A 15-year longitudinal study of 1,291 Shichigahama residents affected by the 2011 Great East Japan Earthquake finds that changes in trauma symptoms over the first two years after a disaster are stronger predictors of long-term mental health than an initial post-disaster assessment.

These findings imply disaster recovery and public health planning should incorporate dynamic screening tools and early interventions to identify and support those at greatest risk in the years following a disaster.

Prediction models that include symptom trajectories over time are markedly more accurate than models relying on a single early assessment, highlighting the value of regular mental health check-ups after disasters.

Lead researchers stress that continuous follow-up is crucial to identifying those most at risk and guiding timely support and interventions.

Publication: Posttraumatic Stress Dynamics and 15-Year Persistence in Great East Japan Earthquake Survivors in JAMA Network Open.

Authors include Hiroaki Tomita and Xue Li; DOI: 10.1001/jamanetworkopen.2026.29441.

Early post-disaster sleep disturbance emerged as a key risk factor for persistent trauma symptoms and may serve as an early intervention target.

Over 15 years, researchers identified five distinct trajectories of posttraumatic stress reactions, with 14.7% of participants still showing clinically significant symptoms after the period.

Future work includes developing screening tools and early interventions based on symptom dynamics and exploring biological and social factors driving worsening trajectories to strengthen community mental health support after future disasters.