Evaluation of Trust Within a Community After Survivor Relocation Following the Great East Japan Earthquake and Tsunami

IMPORTANCE: Trust is a core component of social cohesion, facilitating cooperation and collective action in the face of adversity and enabling survivors to remain resilient. Residential stability is an important prerequisite of developing trusting relations among community members. However, little is known about whether the movement of internally displaced persons (IDPs) after a disaster might change community relations. OBJECTIVE: We explored perceived changes in trust within 1 community directly impacted by the 2011 Great East Japan Earthquake and Tsunami. DESIGN, SETTING, AND PARTICIPANTS: This prospective cohort study examined survey data from 3594 residents of Iwanuma City, Japan, aged 65 years or older. Data were obtained from the Iwanuma Study—part of the Japan Gerontological Evaluation Study, a nationwide cohort study established in 2010—approximately 7 months before the disaster. All Iwanuma City residents age 65 years or older (8576 residents) were eligible to participate in 2010. The response rate was 59.0% (5058 residents). A follow-up survey was conducted in 2013, approximately 2.5 years after the disaster. Of the 4380 remaining participants who answered the baseline survey, 3594 were recontacted (follow-up rate, 82.1%). Data analysis was performed from July 1, 2019, to January 9, 2020. EXPOSURES: The number of temporarily relocated Iwanuma City survivors within 100 m and 250 m of a nonrelocated resident’s home address. MAIN OUTCOMES AND MEASURES: Perceived changes in particularized trust (ie, trusting people from the same community) and generalized trust (trusting people from other communities) measured on a 5-point Likert scale. RESULTS: Among 3250 nonrelocated residents (1808 [55.6%] women; mean [SD] age, 76.5 [6.2] years) of Iwanuma City included in the analytic sample, multivariable-adjusted multinomial logistic regression analyses found that each standard deviation increase in the influx of internally displaced persons (1 SD = 11 IDPs) within 250 m of a resident’s home address was associated with higher odds of a decrease in the resident’s particularized and generalized trust (odds ratio, 1.17; 95% CI, 1.04-1.32). CONCLUSIONS AND RELEVANCE: The influx of IDPs in the host community appeared to be associated with an erosion of trust among locals. To avoid the erosion of social cohesion after a disaster, it may be crucial to provide opportunities for social interaction between old and new residents of communities.