Reducing depressive symptoms after the Great East Japan Earthquake in older survivors through group exercise participation and regular walking: a prospective observational study

OBJECTIVES Survivors of the 2011 Great East Japan Earthquake have an increased risk of depressive symptoms. We sought to examine whether participation in group exercise and regular walking could mitigate the worsening of depressive symptoms among older survivors. DESIGN Prospective observational study. SETTING Our baseline survey was conducted in August 2010, ∼7 months prior to the Great East Japan Earthquake and tsunami, among people aged 65 or older residing in Iwanuma City, Japan, which suffered significant damage in the disaster. A 3-year follow-up survey was conducted in 2013. PARTICIPANTS 3567 older survivors responded to the questionnaires predisaster and postdisaster. PRIMARY OUTCOME MEASURES Change in depressive symptoms was assessed using the 15-item Geriatric Depression Scale (GDS). RESULTS From predisaster to postdisaster, the mean change in GDS score increased by 0.1 point (95% CI -0.003 to 0.207). During the same interval, the frequency of group exercise participation and daily walking time also increased by 1.9 days/year and 1.3 min/day, respectively. After adjusting for all covariates, including personal experiences of disaster, we found that increases in the frequency of group exercise participation (B=-0.139, β=-0.049, p=0.003) and daily walking time (B=-0.087, β=-0.034, p=0.054) were associated with lower GDS scores. Interactions between housing damage and changes in group exercise participation (B=0.103, β=0.034, p=0.063) and changes in walking habit (B=0.095, β=0.033, p=0.070) were marginally significant, meaning that the protective effects tended to be attenuated among survivors reporting more extensive housing damage. CONCLUSIONS Participation in group exercises or regular walking may mitigate the worsening of depressive symptoms among older survivors who have experienced natural disaster.