Original Investigation | Public Health

Evaluation of Trust Within a Community After Survivor Relocation
Following the Great East Japan Earthquake and Tsunami
Krisztina Gero, MD, PhD; Jun Aida, DDS, PhD; Katsunori Kondo, MD, PhD; Ichiro Kawachi, MD, PhD

Abstract
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 mightchange community relations.

Key Points
Question How is the movement ofinternally displaced survivors in theaftermath of a disaster associated withperceived trust towards others within ahost community?
Findings In this cohort study thatOBJECTIVE We explored perceived changes in trust within 1 community directly impacted by the

included 3250 adults aged 65 years or2011 Great East Japan Earthquake and Tsunami.

older, each standard deviation increasein the influx of temporarily relocated

DESIGN, SETTING, AND PARTICIPANTS This prospective cohort study examined survey data fromsurvivors within 100 m of a resident’s

3594 residents of Iwanuma City, Japan, aged 65 years or older. Data were obtained from thehome address was associated with a

Iwanuma Study—part of the Japan Gerontological Evaluation Study, a nationwide cohort study

decrease in their trust in both people

established in 2010—approximately 7 months before the disaster. All Iwanuma City residents age 65

from their community and outside of it.

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 thedisaster. Of the 4380 remaining participants who answered the baseline survey, 3594 wererecontacted (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

Meaning The findings of this study
suggest that opportunities for social
interaction between old and new
residents of host communities may be
crucial for maintaining social trust.

of a nonrelocated resident’s home address.

+ Supplemental content

MAIN OUTCOMES AND MEASURES Perceived changes in particularized trust (ie, trusting people

Author affiliations and article information arelisted at the end of this article.

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 adisaster, it may be crucial to provide opportunities for social interaction between old and new
residents of communities.
JAMA Network Open. 2020;3(11):e2021166. doi:10.1001/jamanetworkopen.2020.21166

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Introduction
The long-term health sequelae of disasters range from mental health problems (eg, depression,anxiety, posttraumatic stress disorder, psychological distress) to functional decline (eg, cognitive
and/or physical disability).1-5 A critical feature of communities that enable survivors to remain
resilient in the face of adversity is the strength of social connections, known as social capital.4,6-8
Tightly knit communities are more effective in mobilizing assistance to the neediest members of thegroup, before even first responders have reached the scene, and long before formal mechanisms of
insurance can become activated. During the recovery phase of disasters, socially cohesive groups are
more effective in giving voice to the needs of the community, and in preventing the exit of members
from disaster-stricken areas.9
Unfortunately, disasters are also commonly associated with major disruptions in social
connections through the residential displacement of survivors. Such disruption of social relations
affects not only the survivors who become separated from their predisaster communities, but also
the host communities, which have to deal with a large influx of internally displaced persons (IDPs).
Previous studies have documented the effects of residential dislocation on the social connections ofdisaster victims.10 However, few studies have focused on the impacts on communities at thereceiving end of large inflows of IDPs. In the 2011 Great East Japan Earthquake and Tsunami, nearly aquarter of a million residents were forced to relocate to new communities. Japanese media at thetime highlighted instances of local friction caused by the large internal flows of disaster victims into
nearby communities.11,12 However, to our knowledge, no systematic attempt has been made to
document the impact of mass residential relocation on the quality of social connections in the hostcommunity.
In this study, we took advantage of a unique natural experiment stemming from the 2011
disaster. The city of Iwanuma (population 44 000) in Miyagi prefecture, located 80 km to the westof the earthquake epicenter, was one of the field sites for a nationwide cohort study of healthy aging,called Japan Gerontological Evaluation Study (JAGES). Our study specifically focused on theassociation of disaster with the erosion of social trust. Generalized trust—the belief that most people,
including strangers, can be trusted—represents a crucial component of social capital, facilitating
cooperation and collective action for mutual benefit.13 In turn, generalized trust has been linked tobetter health outcomes not only in the context of disasters, but in the general population as
well.4,14-19
Previous studies have demonstrated that generalized trust in the community is associated withfactors such as residential stability and ethnic homogeneity.20 Residential stability is recognized as
an important prerequisite for developing community trust. Trust develops over time as a result of
repeated social interactions (eg, the trading of mutual favors) between members of stablecommunities. For example, research suggests that Japanese communities reporting the highest
levels of generalized trust among residents tend to be the oldest communities in continuous
existence based on historical maps.21 Residential homogeneity (eg, by ethnicity) is also correlatedwith levels of trust, especially in the United States, where studies consistently reported a negative
association between ethnic diversity and social cohesion.20
Japan is a notably homogeneous society (by ethnicity) owing to over 2 centuries of exclusion ofpeople born outside of Japan (beginning with the sakoku edict of the Tokugawa era). Nevertheless,the 2011 disaster provides a pertinent natural experiment for examining outcomes associated withthe mass influx of so-called outsiders into existing communities.
In the literature, a critical distinction is drawn between particularized trust (the belief thatcertain known others can be trusted) vs generalized trust, which includes trust of unknown groups
and strangers.20 We hypothesized that the influx of IDPs into a community would be associated witha decrease in generalized trust but not particularized trust. However, previous studies suggest that
community heterogeneity has broader spillover effects in eroding generalized trust.20 Therefore, toJAMA Network Open. 2020;3(11):e2021166. doi:10.1001/jamanetworkopen.2020.21166 (Reprinted)

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address knowledge gaps, we explore potential differences between the associations of disaster withgeneralized vs particularized trust within the host community.

Methods
Study Population
Data were obtained from the Iwanuma Study, a part of the JAGES nationwide cohort study
established in 2010 to examine factors associated with healthy aging of community-dwelling
residents in 31 municipalities throughout Japan. On March 11, 2011, a magnitude 9 earthquake
occurred at the Pacific coast of Tohoku prefecture, affecting one of the participating municipalities,
Iwanuma City, which was located approximately 80 km west of the epicenter and in the direct line of
the resulting tsunami. The disaster claimed the lives of 180 residents, flooded 48% of the town’s landarea, and damaged 5542 housing units.22
In August 2010, around 7 months before the disaster, a census was conducted for every
Iwanuma City resident aged 65 years or older identified through the local official residential registry.
In October 2013, approximately 2.5 years after the disaster, the town’s residents were recontacted,
and an in-home survey was conducted to gather information on the health status and social capital of
the survivors.
Informed consent was obtained from participants at the time of data collection. This study
excluded respondents who incompletely signed consent forms, and the analytic sample wasrestricted to the 3250 individuals (1442 men and 1808 women) who were not relocated due to theearthquake (eFigure in the Supplement). The study protocol was approved by the ethics committeesof Nihon Fukushi University, Chiba University, Tohoku University, and the Harvard T. H. Chan Schoolof Public Health. This study followed the Strengthening the Reporting of Observational Studies in
Epidemiology (STROBE) reporting guideline.

Social Trust
To measure perceived changes in trust in others in the wake of the earthquake, in the JAGES 2013
survey study participants from Iwanuma City were asked the following questions: (1) ”How did yourtrust in people in your community change from before the earthquake?” and (2) “How did your trust inpeople from other communities change from before the earthquake?” Of 3250 nonrelocatedparticipants, 3216 (1787 [55.6%] women) answered the first, and 3210 (1785 [55.6%] women)answered the second question. Possible answers included “became much stronger,” “became
stronger,” “did not change,” “became weaker,” and “became much weaker.”

Number of IDPs in the Host Community
The 2013 survey also asked the following question: “Did you move to a new residence because of theearthquake?” The possible answers were: (1) “No,” (2) “The entire district was relocated to temporary
housing” (kasetsu jutaku: similar to FEMA-style trailer homes in the US), (3) “Moved to temporary
housing, but not by entire district relocation,” (4) “Moved to minashi kasetsu temporary housing”(rental housing on the open market), and (5) “Purchased a new home.” Because of the disaster, 131
study participants were forced to move to temporary housing, either alone (47 participants) or
together with others from their district (84 participants).
Using data from the local residential registry, home address coordinates of everyone in
Iwanuma city aged 65 years or older (including those who did not respond to the JAGES surveys)
were verified both in 2010 and 2013, enabling us to identify a further 303 relocated residents. Using
these home address coordinates for 2013, the geodetic distance between each nonrelocated andrelocated participant was calculated, from which the number of IDPs within a 100 m and 250 m
buffer zone of each nonrelocated resident was determined.

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Covariates
As potential confounders associated with both trust and housing location, the following baselinevariables measured in 2010 were included in the multivariate-adjusted models: education (<10 orⱖ10 years), employment status (paid job, retired, or never been employed), equivalized income(<¥1.49 million or ⱖ¥1.49 million per year [approximately US$ 14 900]), and marital status (married,
divorced, widowed, or single/other). We also adjusted for variables possibly associated withperceptions of trust, including age (measured as a continuous variable in years), sex, living alone,
losing a close relative or friend due to the earthquake, and depressive symptoms, all of which were
measured in 2013. Equivalized income was calculated by dividing the gross annual household incomeby the square root of the number of household members. Depressive symptoms were measured
using the short version of the Japanese Geriatric Depression Scale (GDS-15), a self-administeredquestionnaire consisting of 15 questions with yes or no as possible answers. With higher scoresindicating higher depressive symptomatology, a GDS-15 score of 5 or more was used as a predefined
cut-off point to create a binary variable.23-25

Statistical Analysis
To assess whether IDPs were relocated to areas where residents already had low trust predisaster,levels of particularized trust (ie, measuring agreement with the question, “Do you think people living
in your area can be trusted in general?” on a Likert scale ranging from 1 to 5) and generalized trust (ie,yes, no, or maybe responses to the question, “Do you feel that people can generally be trusted?”)among all participants in Iwanuma city were confirmed using the JAGES 2010 survey. Sequential
regression multiple imputation (or imputation by fully conditional specification or by using chained
equations) was conducted, including all variables of the final analytical model to account for missing
covariate data (missingness, 0%-12.3%). After creating 10 imputed data sets, multinomial logistic
regression models were used to estimate multivariate-adjusted odds ratios (OR) with 95% CIs forperceived change in trust after the earthquake. For better comparability and reliability, exposure
variables were standardized. Considering that outlier values might skew the probability distribution,robust standardization (value = [value − median]/[75th percentile − 25th percentile]) was used.
After confirming that the interaction terms between the explanatory variables and sex were notstatistically significant, data from men and women were combined in all analyses.
Two sets of models were constructed to estimate the association between the number of IDPs
in the proximity of nonrelocated residents within 100 and 250 m and perceived change in trust inothers. Model 1 is a univariate model. Model 2 controlled for equivalent income, education, marital
status, employment status, single residence, the death of a relative as a result of the disaster, thedeath of a friend as a result of the disaster, and depressive symptoms. SAS version 9.4 (SAS InstituteInc) was used to conduct all analyses. The data were analyzed from July 1, 2019, to January 9, 2020.
All tests were 2-tailed, with a significance level of P < .05.

Results
Of 8576 identified residents contacted to participate in 2010 who were aged 65 years or older, 5058
(59.0%) responded. Of 4380 eligible participants who answered the baseline survey, 3594 wererecontacted in 2013, constituting an 82.1% follow-up rate (eFigure in the Supplement).
Table 1 presents the descriptive characteristics of Iwanuma study respondents. Among the3250 nonrelocated participants, the mean (SD) age was 76.5 (6.2) years, and 1808 (55.6%) were
women. At baseline, 1087 participants (33.5%) had less education (<10 years of educational
attainment), and 997 (30.7%) reported low household income (annual income <¥1.49 million). As fordisaster experiences, 808 participants (24.9%) and 464 (14.3%) lost a close relative or friend,
respectively. Approximately one-third (32.6%) also reported depressive symptoms in the follow-up
survey, while 70 (2.2%) had lower trust in people from other areas and 73 (2.3%) had lower trust ofpeople in their own area. Compared with nonrelocated participants, IDPs were more likely to have
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low education levels (63.4% [83 participants] vs 33.5%) and low household income (51.9% [68participants] vs 30.7%) predisaster. They were also more likely to experience the loss of a relative(56.5% [74 participants] vs 24.9%) or friend (32.8% [43 participants] vs 14.3%), and to report
depressive symptoms (61.1% [80 participants] vs 32.6%) and lower trust in people from their own(15.3% [20 participants] vs 2.3%) or other communities (10.7% [14 participants] vs 2.2%) after theearthquake. There were no significant differences between all Iwanuma study respondents and thenonrelocated participants in the examined factors, except for a slightly lower proportion of
nonrelocated residents with low educational attainment (all respondents, 35.8% vs nonrelocatedrespondents, 33.5%; P = .046).
Figure 1 and Figure 2 display the distribution of IDPs within a 100 m and a 250 m buffer zone,
respectively. The number of IDPs generally ranged from 0 to 8 within a 100 m area, and 0 to 26
within a 250 m area of the nonrelocated residents. However, owing to group relocation, some
districts experienced an increased influx of displaced survivors, ranging from 21 to 87 people within a
100 m area, and 89 to 157 individuals within a 250 m buffer zone.

Table 1. Participant Characteristics
Participants, No. (%)
CharacteristicAll(n = 3567)

Nonrelocated(n = 3250)

Internally displaced(n = 131)

Women

2015 (56.5)

1808 (55.6)

80 (61.1)

Low educational attainment (<10 y)1277 (35.8)

1087 (33.5)

83 (63.4)

Retired2228 (62.5)

2060 (63.4)

72 (55.0)

Equivalized household income <¥1.49 million/ya

1152 (32.3)

997 (30.7)

68 (51.9)

Married2517 (70.6)2310 (71.1)

91 (69.5)

Divorced

94 (2.6)

87 (2.7)

3 (2.3)

Widowed868 (24.3)

776 (23.9)

32 (24.4)

Single or other88 (2.5)

77 (2.4)

5 (3.8)Age, mean (SD), y

76.5 (6.2)

76.5 (6.2)

76.9 (6.6)

Living alone

407 (11.4)

374 (11.5)

17 (13.0)

Lost a close relative

936 (26.2)

808 (24.9)

74 (56.5)

Lost a close friend

549 (15.4)

464 (14.3)

43 (32.8)

GDS-15 score ≥51218 (34.1)

1059 (32.6)

80 (61.1)

Low trust in people from other areas

92 (2.6)

70 (2.2)

14 (10.7)

Low trust in people within the area

103 (2.9)

73 (2.3)

20 (15.3)

2010 survey

2013 survey

Abbreviation: GDS-15, Japanese GeriatricDepression Scale.
a

Approximately US$ 14 900.

Figure 1. Distribution of Internally Displaced Persons Within a 100 m Buffer Zone in 2013 in Iwanuma
60

50Percentage

40

30

20

10

0
0

1

2

3

4

5

7

8

21

22

67

87

Internally displaced survivors, No.

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Table 2 shows levels of household income and generalized and particularized trust among
JAGES participants in Iwanuma City before the 2011 Earthquake and Tsunami. Participants living inschool districts with temporary housings built postdisaster were less likely to report low generalized
trust in 2010 compared with those from other school districts. There were no significant differencesin predisaster mean particularized trust scores between residents of group relocation affected andother areas. Residents from flooded communities reported a significantly lower predisaster mean
household income compared with those from communities without postdisaster temporary housing
units. However, there were no significant mean household income differences between the host andthe disaster-effected school districts.
Table 3 provides multivariate-adjusted ORs with 95% CIs for change in trust after theearthquake associated with the number of IDPs in the participants’ proximity. An increase in thenumber of IDPs within 100 or 250 m of participants’ home addresses was associated with higher
odds of a decrease in the trust of nonrelocated residents, both for people from their own and othercommunities. After controlling for all covariates (Model 2), the OR for “much weaker trust” after theearthquake (compared with “no change in trust”) per each standard deviation increase in the numberof relocated people within 100 m (SD = 1 IDP) was 1.08 (95% CI, 1.03-1.13) related to generalized
trust, and 1.08 (95% CI, 1.04-1.14) related to localized trust. The corresponding ORs with each SD
increase within a 250 m radius (SD = 11 IDPs) were 1.17 (95% CI, 1.04-1.32) for both generalized andlocal trust. The OR estimates did not significantly change when covariates were excluded from themodel (Model 1).

Figure 2. Distribution of Internally Displaced Persons Within a 250 m Buffer Zone in 2013 in Iwanuma
20

Percentage

16

12

8

4

0
0

1

2

3

4

5

6

7

8

9

10 11 12 13 14 15 17 21 22 23 24 25 26 89 90 92 154 157

Internally displaced survivors, No.

Table 2. Household Income and Levels of Generalized and Particularized Trust PredisasterAmong JAGES 2010 Panel Participants
Residents, No.
Communities without
temporary housing units(n = 3158)

All host
communities(n = 409)

Main hostcommunity(n = 133)a

Floodedcommunities(n = 565)

3094

393

128

547

Abbreviations: JAGES, Japan Gerontological
Evaluation Study; NR, none reported.

3.8 (0.8)

3.7 (0.8)

3.6 (0.9)

3.7 (0.8)

a

831

49

0

59

The school district with the highest number ofinternally displaced persons.

b

Low trust, No. (%)

76 (9.1)

3 (6.1)NR

6 (10.2)

Equivalized householdincome, ¥10 000c

2535

318

100

433

An extended version of the JAGES 2010 survey
containing a question related to generalized trust
was distributed to a randomly selected 20% of thestudy participants.

235.2 (152.5)

222.1 (164.5)

214.9 (181.2)

201.9 (144.8)cEach unit represents ¥10 000 (approximately
US$ 100).

Particularizedtrust responses
Mean (SD) Likert
score, 1-5
Generalized trust
responsesb

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Discussion
Our study found that after the 2011 Tohoku Earthquake, the influx of IDPs to another community was
associated with weakening of both generalized and local trust, suggesting that the concentration of
IDPs within a temporary shelter village (as happened in Iwanuma) may have a particularly
detrimental effect on social cohesion.
Building trust between residents of a community depends on repeated social interactions overan extended period of time, whereas exposure to outsiders or out-groups can trigger conflict andmistrust.20 In a 2007 study, Putnam26 found that the influx of immigrants in communities can spur
perceived competition over scarce resources (eg, housing, schools), ultimately resulting in reduced
community cooperation and altruism, as well as lower trust not only in people perceived as different,
but also in those who are perceived as similar. This study found that internal forced migration after adisaster, even within the same city from 1 district to another, might also lead to the erosion of thetrust of nonrelocated residents in people from other communities as well as in people from the samecommunity.
Previously, we reported that relocating IDPs together as a group, as opposed to randomly
housing them throughout the community, can be an effective means of preserving social
connections and strengthening the resilience of disaster survivors.10 However, the same policy may
also inadvertently promote erosion of trust between older residents of the host community andnewcomers.
We have therefore identified a potential dilemma in postdisaster resettlement. Our previous
studies10,27,28 have reported that the resettlement of survivors needs to take into account thepreexisting social ties within a disaster-effected community in order to prevent the loss ofcommunality associated with widespread housing destruction. In Iwanuma, the city offered 2
different means of relocation to temporary housing to survivors. People could choose between
individual relocation—moving to public housing by a random lottery or seeking housing in the open
rental market—or group relocation, in which whole communities would be moved together as a

Table 3. Multivariate Adjusted ORs for Change in Trust After the Earthquake Associated With the Number of IDPs Within a 100- to 250-m Area
Trust in people from other areas
Responses

Respondents,
No.

IDPs Within 100 m, OR(95% CI)/1 SD (1 IDP)a

Trust in people from your area
IDPs Within 250 m, OR(95% CI)/1 SD (11 IDPs)a

Respondents,
No.

IDPs Within 100 m, OR(95% CI)/1 SD (1 IDP)a

IDPs Within 250 m, OR(95% CI)/1 SD (11 IDPs)aModel 1b
No change

2706

1 [Reference]

1 [Reference]2554

1 [Reference]

1 [Reference]

Much weaker since
the earthquake

12

1.07 (1.03-1.11)c

1.15 (1.03-1.29)d12

1.07 (1.03-1.11)c

1.16 (1.04-1.29)c

Weaker since
the earthquake

58

0.89 (0.73-1.09)

0.92 (0.71-1.19)

61

0.89 (0.73-1.08)

0.97 (0.80-1.17)

Stronger since
the earthquake

400

0.92 (0.86-0.99)d0.93 (0.85-1.02)

553

0.96 (0.91-1.01)

0.95 (0.89-1.02)

Much stronger since
the earthquake

34

0.80 (0.58-1.10)

0.81 (0.49-1.34)

36

0.84 (0.62-1.12)

0.90 (0.63-1.29)

Model 2e

No change

2706

1 [Reference]

1 [Reference]2554

1 [Reference]

1 [Reference]

Much weaker since
the earthquake12

1.08 (1.03-1.13)f

1.17 (1.04-1.32)d12

1.08 (1.04-1.14)f

1.17 (1.04-1.32)c

Weaker since
the earthquake

58

0.89 (0.73-1.08)

0.94 (0.74-1.20)

61

0.89 (0.74-1.08)

0.98 (0.82-1.17)

Stronger since
the earthquake

400

0.92 (0.86-0.99)d0.94 (0.86-1.03)

553

0.96 (0.91-1.01)

0.95 (0.88-1.02)

Much stronger since
the earthquake

34

0.81 (0.59-1.12)

0.84 (0.53-1.34)

36

0.83 (0.62-1.11)

0.89 (0.60-1.31)

Abbreviations: IDP, internally displaced person; OR, odds ratio.

dP < .05.

aStandard deviation calculated by robust standardization (value = [value − median]/[75th percentile − 25th percentile]) to adjust for potential outliers.

ebModel 1 is a univariate model.

Model 2 adjusted for age, sex, equivalized household income, education, marital status,
employment status, living alone, losing a family member, losing a close friend, anddepressive symptoms.

c

P < .01.

f

P < .001.

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group into prefabricated temporary housing villages (resembling FEMA-style trailer parks in the US).
Families who wanted to escape the emergency shelters as soon as possible selected the individual
option, so they could leave the shelters as soon as their number came up on the lottery. However, thismode of resettlement had the unintended consequence of disrupting existing social connections in
the community and scattering the residents randomly throughout the trailer settlement. We
previously found that people selecting the lottery option reported lower levels of social participationand social support.10,28 By contrast, people selecting group resettlement were even more likely to
be engaged in informal social participation 3 years after the disaster compared with before thedisaster.10 However, as the result of our present analysis suggests, the option of moving large
numbers of IDPs together and concentrating them into 1 location may lead to greater friction withestablished residents of host communities.

Limitations
Several limitations need to be considered while interpreting the findings of this study. First, although
we controlled for socioeconomic status, depressive symptoms, and personal disaster experiences,
there may be residual confounders that we failed to take into account. Second, the number ofnonrelocated participants reporting much weaker trust after the earthquake is quite small (12participants), resulting in relatively wide 95% CIs around the point estimates. Therefore, the results
have to be interpreted with caution. Third, because of the uneven distribution of displaced survivors
in the community, we were unable to determine the precise threshold between 8 and 21 IDPs whenthe erosion of trust began to occur. The results suggest that the resettlement of a few scatteredindividuals in a community was not associated with changes in on local trust. The erosion of trust
seemed to appear when larger numbers of people moved in. Fourth, we do not have information on
the residential movements of people younger than 65 years, which might not be correlated with the
movement of people aged 65 years or older. On the other hand, two-thirds of the population of thecity of Iwanuma were aged 65 years or older before the disaster, and the age structure of IDPs was
similar. Fifth, it is not clear how participants define people from their community and people fromother communities. By 2013, when the question was asked, IDPs had spent approximately 2.5 years
in their new environment. Thus, the respondents may have perceived the displaced population as
either people from their own community or as outsiders. Hence, the 2 questions about trust might
not have distinguished between particularized and generalized trust, which would also explain thesimilarity of the corresponding OR estimates. Also, perceived change in trust was measured based on
1 question instead of a multi-item scale, which hindered a more precise assessment of trust levels
among the respondents. Sixth, the question of the generalizability of our results needs to beconsidered due to the relatively low response rate (59%) on the baseline survey. However, previous
reports based on the JAGES study confirmed that the demographic profile of the participants issimilar to the rest of the residents aged 65 years or more in Iwanuma City.7,10 Moreover, a 59%
response rate is comparable with other studies on community-dwelling respondents.29

Conclusions
In conclusion, while a well-designed group relocation is crucial for preserving social capital andensuring better disaster resilience among displaced survivors, a higher concentration of IDPs mightlead to the erosion of trust among the residents of the host community. To avoid the erosion of social
cohesion, it may be crucial to provide programs for meaningful interactions between the old and new
residents of the community.26 More research is needed to understand the short-term and longterm impact of different relocation practices on both displaced and nondisplaced survivors of
disasters.

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ARTICLE INFORMATION
Accepted for Publication: August 7, 2020.
Published: November 5, 2020. doi:10.1001/jamanetworkopen.2020.21166
Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2020 Gero K et al.
JAMA Network Open.
Corresponding Author: Krisztina Gero, MD, PhD, Department of Health Sciences, Bouvé College of Health
Sciences, Northeastern University, 360 Huntington Ave, 435 International Village, Boston, MA 02115 (k.gero@northeastern.edu).
Author Affiliations: Department of Social and Behavioral Sciences, Harvard T. H. Chan School of Public Health,Boston, Massachusetts (Gero, Kawachi); Department of Health Sciences, Bouvé College of Health Sciences,
Northeastern University, Boston, Massachusetts (Gero); Department of International and Community Oral Health,
Tohoku University Graduate School of Dentistry, Miyagi, Japan (Aida); Center for Preventive Medical Sciences,
Chiba University, Chiba, Japan (Kondo); Center for Gerontology and Social Science, National Center for Geriatrics
and Gerontology, Aichi, Japan (Kondo).
Author Contributions: Drs Gero and Kawachi had full access to all of the data in the study and take responsibility
for the integrity of the data and the accuracy of the data analysis.
Concept and design: Gero, Kawachi.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Gero, Aida.
Critical revision of the manuscript for important intellectual content: Aida, Kondo, Kawachi.
Statistical analysis: Gero.
Obtained funding: Kondo, Kawachi.
Administrative, technical, or material support: Kondo.
Supervision: Aida, Kawachi.
Conflict of Interest Disclosures: Dr Kondo reported receiving grants from the NEC Corporation, Ryobi Systems
Co, Ltd, RESOL SEIMEI NO MORI Co, Ltd, and the National Center for Geriatrics and Gerontology outside thesubmitted work. No other disclosures were reported.
Funding/Support: We appreciate the support and cooperation of the Iwanuma mayor’s office and the staff of the
Department of Health and Welfare of the Iwanuma city government. This work was supported by National
Institutes of Health grant R01 AG042463 and R01 AG042463-06; Grants-in-Aid for Scientific Research from theJapan Society for the Promotion of Science (Nos. KAKENHI 23243070, KAKENHI 22390400, and KAKENHI
24390469); Health Labour Sciences Research Grant from the Japanese Ministry of Health, Labour, and Welfare
Nos. H22-Choju-Shitei-008 and H24-Choju-Wakate-009; grant S0991035 from the Strategic Research
Foundation Grant-Aided Project for Private Universities from the Japanese Ministry of Education, Culture, Sports,
Science, and Technology; and research and development grants for longevity science from the Japan Agency for
Medical Research and Development.
Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection,
management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; anddecision to submit the manuscript for publication.
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SUPPLEMENT.
eFigure. Participant Flow Chart, Iwanuma, Japan, 2010-2013

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