Nearly 15 years after the Great East Japan Earthquake, many survivors are still living with the psychological effects of the disaster. A new study from Tohoku University has found that changes in trauma symptoms during the first two years after a disaster are a much better predictor of long-term mental health than a single assessment taken shortly after the event.
Details of the findings were published in JAMA Network Open on August 14, 2026.
“Our findings suggest that disaster survivors should receive regular mental health check-ups during the years following a disaster, rather than relying on one-time screening,” says Hiroaki Tomita, a professor at Tohoku University’s Graduate School of Medicine who helped lead the study. “By identifying people whose symptoms worsen over time, healthcare providers may be able to offer support before problems become long-lasting.”
Tomita and his colleagues followed 1,291 residents of Shichigahama whose homes were severely damaged or destroyed by the 2011 Great East Japan Earthquake and tracked their mental health over a period of 15 years – the longest continuous study of its kind.
Using a statistical method that grouped people according to how their symptoms changed over time, the team identified five different long-term patterns of posttraumatic stress reactions (PTSR). They found that 14.7% of participants continued to experience clinically significant trauma symptoms 15 years after the disaster, highlighting that psychological effects can persist for well over a decade.
The researchers also found that symptom severity immediately after the disaster was not the best indicator of long-term recovery. Instead, whether symptoms improved or worsened during the first two years proved to be far more important.
People whose symptoms became worse between the first and second year after the disaster were more than five times more likely to still experience significant trauma symptoms 15 years later than those whose early symptoms did not persist. This relationship remained strong even after accounting for factors such as age, sex, resilience, sleep problems, and the severity of symptoms at the initial assessment.
When the researchers compared different prediction models, those that included changes in symptoms over time were much more accurate than those based on a single early assessment. This demonstrates the value of repeated follow-up evaluations for identifying people at risk of long-term psychological distress.
The study also identified sleep disturbance during the early post-disaster period as an important risk factor linked to persistent trauma symptoms. Because sleep problems can often be treated, they may provide an opportunity for early intervention that could improve long-term mental health outcomes.
The findings have important implications for disaster recovery and public health. As specialized disaster mental health services eventually transition back to routine community healthcare, people with worsening symptoms may be overlooked if support depends only on an initial screening.
“Our findings show that recovery after a disaster is not a fixed process,” says Xue Li, an assistant professor at Tohoku University’s Graduate School of Medicine who also helped lead the research.” Monitoring how symptoms change during the first two years provides much clearer insight into who may need long-term support. Continuous follow-up, rather than a single assessment, should become a key part of disaster mental healthcare.”
The researchers hope their findings will help improve community mental health programs by supporting the development of screening tools and early intervention strategies that identify people at greatest risk of long-term trauma. They also plan to investigate the biological and social factors that contribute to worsening symptoms, with the goal of strengthening mental health support as communities recover from future disasters.
- Publication Details:
Title: Posttraumatic Stress Dynamics and 15-Year Persistence in Great East Japan Earthquake Survivors
Authors: Xue Li, Hitomi Usukura, Yusuke Utsumi, Moe Seto, Atsushi Sakuma, Kazuho Tomimoto, Terufumi Machida, Yumiko Hamaie, Natsuko Kobayashi, Hiroshi Komatsu, Saya Kikuchi, Shinichi Kuriyama, Naoki Nakaya, Atsushi Hozawa, Yasuto Kunii, Hiroaki Tomita
Journal: JAMA Network Open
