Original Investigation | PsychiatryLong-term Trends in Mental Health Disorders Afterthe 2011 Great East Japan Earthquake and Tsunami
Shiho Kino, PhD; Jun Aida, DDS, PhD; Katsunori Kondo, MD, PhD; Ichiro Kawachi, MD, PhD

Abstract
IMPORTANCE Posttraumatic stress symptoms (PTSS) and depressive symptoms are common
among survivors of a major disaster, yet few longitudinal studies have documented their long-term
persistence at the community level.
OBJECTIVE To examine the trajectories of PTSS and depressive symptoms for as long as 5.5 years
after the 2011 Great East Japan earthquake and tsunami.

Key Points
Question What is the persistence ofmental illness symptoms amongindividuals affected by the 2011 Great
East Japan earthquake and tsunami 5.5
years after the disaster?
Findings In a cohort study of 2781
community-dwelling older adults,

DESIGN, SETTING, AND PARTICIPANTS This cohort study used data from 2781 participants in 3

approximately half of the individuals

waves of the Iwanuma Study (2010, 2013, and 2016), a cohort of community-dwelling older adults

who reported posttraumatic stress(ⱖ65 years in August 2010) in Iwanuma, Japan, who were directly affected by the 2011 disaster. The

symptoms and depression after thebaseline assessment of mental health predated the disaster by 7 months, and survivors weredisaster had recovered by 5.5 years. The

followed up for 5.5 years after the disaster. Data analysis was performed from October 2019 to

overall prevalence of depression

February 2020.

remained stable between predisasterand postdisaster data.

EXPOSURES The March 11, 2011, Great East Japan earthquake and tsunami.

Meaning In this study, although mental
illness symptoms persisted for more

MAIN OUTCOMES AND MEASURES PTSS were measured by 9 questions on the Screening
Questionnaire for Disaster Mental Health, while depressive symptoms were measured by 15 items on
the Geriatric Depression Scale short form.

than 5 years among half of disastersurvivors, the community-wide
prevalence of depression remained
unchanged, suggesting that the

RESULTS The analytic samples for trajectories of PTSS and depressive symptoms included 2275 andcommunity itself was resilient.

1735 respondents, respectively. In the study population at baseline, there were slightly more women(1262 of 2275 [55.5%] and 882 of 1735 [50.8%]), and most participants were aged 65 to 74 years(1533 [67.4%] and 1224 [70.5%]) and married (1664 [76.2%] and 1319 [77.7%]). Overall, there was a
13.6% (95% CI, 11.7%-15.6%) incidence of depression among individuals who did not have depression

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

before the disaster, while a further 11.1% (95% CI, 9.8%-12.4%) reported PTSS after the disaster. By
5.5 years of follow-up, approximately half of the survivors with new depressive symptoms in 2013(85 of 168 [50.6%]) and PTSS (147 of 253 [58.1%]) had recovered. The prevalence of depression in
the community remained remarkably stable (between 504 participants [29.0%] and 506
participants [29.2%]) comparing predisaster and postdisaster data.
CONCLUSIONS AND RELEVANCE In this study, mental illness symptoms persisted for more than 5
years among half of disaster survivors, but the community-wide prevalence of depression remained
stable, suggesting that the community itself was resilient.
JAMA Network Open. 2020;3(8):e2013437. doi:10.1001/jamanetworkopen.2020.13437

Open Access. This is an open access article distributed under the terms of the CC-BY License.
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JAMA Network Open | PsychiatryLong-term Trends in Mental Health Disorders After the 2011 Great East Japan Earthquake and Tsunami

Introduction
It is well established that disasters are associated with an increase in many psychological problems,
including depressive symptoms and posttraumatic stress symptoms (PTSS).1 However, the long-term
prognosis of mental disorders following disaster remains sparsely documented. Few studies havefollowed survivors for more than 3 years.2,3 Even fewer studies have managed to capture the mental
health status of survivors predating their disaster experiences,2,3 so we cannot determine whether
the disaster caused worsening of mental health or whether poor mental health already predated
disaster exposure in affected populations.
Absent a predisaster assessment of mental health status, accurate estimates of the incidence ofmental illness are difficult to obtain.4 Asking survivors to retrospectively recall their mental healthprior to disaster is obviously hampered by recall bias. In 1 of the few existing studies to document
predisaster mental health, Fergusson et al5 followed survivors of the Canterbury earthquakes in New
Zealand during 2010 and 2011. The researchers used the Christchurch Health and Development
Study, a 35-year longitudinal birth cohort (with 635 men and 630 women), in which predisastermental health information was available among survivors. The study found that the prevalence ofsome types of mental disorders (ie, major depression, posttraumatic stress disorder, other anxiety
disorders, and nicotine dependence) was significantly elevated among people who experienced
traumatic events during the earthquakes. However, after adjusting for confounders that wereassessed prior to the earthquakes, the excess risk of mental disorders stemming from disasterrelated experiences was substantially attenuated, with the exception of nicotine dependence.
Turning to the issue of long-term prognosis of mental illness in the aftermath of a disaster,Morina et al3 conducted a systematic review of remission rates from posttraumatic stress disorder in
adults. Among 42 studies with a mean follow-up period of 40 months, they found that posttraumaticstress disorder following disaster-related trauma had the highest mean remission rate (60.0%)
compared with remission of symptoms related to physical disease (31.4%).3 More specifically, 5natural disaster–related studies were found, with an mean period between the disaster event andfollow-up assessment of 21 months (the range for the period between trauma and baseline
assessment was 1.5-6.5 months, and the range for the period between baseline assessment andfollow-up was 12-30 months.).3 However, none of those studies assessed mental health status prior
to the disaster.6-10
According to the findings from a seminal review by Norris et al,11 psychological symptoms peakin the first year after the disaster and tend to improve as time passes, while a delayed onset of thedisorder is less common. Twelve years after Hurricane Katrina, Raker et al12 found that 39% and 29%of people had recovered from PTSS and depressive symptoms, respectively, while 3% and 9%
experienced delayed onset of PTSS and incident depressive symptoms. On the other hand, 14% and
28% had persistent PTSS and depressive symptoms even 12 years after the disaster.12
The factors associated with persistence vs remission of mental illness symptoms remain poorly
understood, especially with regard to risk and protective factors that predate the disaster
experience. Iwanuma city in Miyagi prefecture was 1 of the localities directly affected by the tsunami
on March 11, 2011. The Iwanuma Study is a community-based longitudinal cohort established in 2010that has collected information every 3 years. A unique feature of the Iwanuma Study is that baseline
information from participants was assessed 7 months before the disaster and the follow-up rate
among survivors remains very high. In a series of previous reports,13-16 we documented that levels ofsocial capital predating the disaster were associated with a lower incidence of PTSS and depressive
symptoms. However, our previous reports involved relatively short observation periods(approximately 2.5 years postdisaster) while most of the survivors were still housed in temporary
accommodation. In the present study, we sought to examine long-term prognosis of PTSS anddepressive symptoms among older individuals who experienced the 2011 disaster.

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Methods
Study Population
The Iwanuma Study is a community-based longitudinal cohort established in 2010, when the city of
Iwanuma in Miyagi prefecture (population 44 187 in 2010) was selected as 1 of 31 field sites for anationwide cohort study of healthy aging in Japan, called the Japan Gerontological Evaluation Study(JAGES).17 The baseline of the Iwanuma Study was collected in August 1 to 20, 2010, when a census
was undertaken of all the city’s residents aged 65 years or older. The names and addresses ofresidents were obtained from municipal records, and the baseline postal survey inquired aboutsociodemographic information, health habits, health status, and people’s social connections toothers. The response rate to the baseline survey was 59.0% (5058 of 8576 residents), which iscomparable to similar surveys of community-dwelling residents. Comparison of the baselinecharacteristics of our sample with the general population of the city (assessed from the local
government census) confirmed that the Iwanuma Study participants were representative withrespect to sex and age distribution as well as employment status.14
As summarized in the flowchart (Figure 1), a total of 4957 individuals responded to the baseline(predisaster) survey, 3567 individuals responded to the second (postdisaster) survey (October 1,
2013, to January 31, 2014), and 2810 individuals to the third survey (November 14, 2016, toDecember 5, 2016). We excluded people whose answers of sex and age were substantially different
because the same people might not have answered.
A total of 34 original participants died on the day of the disaster. Among the 2781 valid
responders to the 2016 survey, 506 participants (18.2%) did not complete the PTSS questions oneither second or third survey, while another 1046 participants (37.6%) did not complete depressive
symptoms either at baseline, second survey, or third survey. This left 2275 and 1735 individuals forthe analyses of trajectories of PTSS and depressive symptoms, respectively, across 3 survey waves.
The research protocol was reviewed and approved by the human participants committees ofthe Harvard T.H. Chan School of Public Health, Tohoku University, Nihon Fukushi University, andChiba University. Participants provided written informed consent. All data were deidentified. This
study followed the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE)
reporting guideline for cohort studies.

Outcomes
PTSS
PTSS was measured with the Screening Questionnaire for Disaster Mental Health, which was
originally developed to screen for posttraumatic stress disorder and depression and subsequently
validated for older populations in the 1995 Great Hanshin Earthquake in Japan.18 PTSS was assessedwith 9 questions with binary answers (ie, yes/no) (Box). Affirmative responses were summed (range,0-9), and the guideline suggests that a score of 6 or more is considered severely affected by theevent and possibly with posttraumatic stress disorder, with an area under the receiver operating
curve of 0.91 (95% CI, 0.83, 0.99) compared with the criterion-standard Clinician Administered
Posttraumatic Stress Disorder Scale. Thus, the reliability and validity of this measure are reasonably
high, and this measure was used in our previous studies.14,16
Depressive Symptoms
Depressive symptoms were measured by the Geriatric Depression Scale Short Form, which wasdeveloped to measure depressive symptoms among older adults.19,20 The form has 15 items withbinary answers (ie, yes/no) (Box Responses were summed (range, 0-15) to assess depressive
symptoms, with higher scores indicating more severe depressive symptoms. This scale was validated
to screen major depressive symptoms (ie, a score of 5 or more) with an area under the receiver
operating characteristic curve of 0.94 (sensitivity, 92%; specificity, 87%) against the Structured
Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders, Third Edition, Revised,

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as the criterion standard.21 This measure has been validated to assess depressive symptoms amongolder Japanese populations.13-15
Trajectories of PTSS and Depressive Symptoms
Following Norris et al11 and Raker et al,12 we categorized mental health trajectories into 4 types: neverexperienced PTSS or depressive symptoms, recovered from PTSS or depressive symptoms, had

Figure 1. Study Flowchart8576 Enrolled in first survey
3518 Did not respond
5058 Respondents to first survey(59.0% participation rate)
101 Respondents excluded for invalid
identification, sex, or age
4957 Valid respondents
577 Lost to follow-up
34 Death from Great East Japan
earthquake and tsunami
400 Death from other causes
95 Before the disaster
305 After the disaster
92 Moved out
17 Address unknown
34 Illness
4380 Respondents eligible forsecond survey
786 Did not respond3594 Respondents to second survey(82.1% participation rate)
27 Invalid consent
3567 Valid respondents
244 Lost to follow-up
243 Death from all causes
1 Moved out
3323 Respondents eligible for thirdsurvey513 Did not respond
2810 Respondents (84.6%
participation rate)
29 Excluded for invalid identification
2781 Valid respondents

506 Respondents missing values on
posttraumatic stress symptoms
149 Second survey
397 Third survey

1046 Respondents missing values
on depressive symptoms
348 Baseline
333 Second survey
721 Third survey

2275 Respondents included in
posttraumatic stresssymptoms sample

1735 Respondents included indepressive symptoms
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Summing the individuals with missing values does notmatch the total number because some individuals had
missing values on more than 1 covariate.

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delayed onset of PTSS or depressive symptoms, and had persistent PTSS or depressive symptoms.
For PTSS, the never group included individuals who did not report PTSS in either 2013 or 2016, while
the delayed onset group included individuals who did not report PTSS in 2013 but had developed
symptoms in 2016. The recovered group included those with PTSS in 2013 but not in 2016. Finally,
the persistent group included those reporting PTSS in both 2013 and 2016.
Questions regarding depressive symptoms were asked in all 3 waves; therefore, following themethods of Raker et al,12 we categorized the possible trajectories as follows: the never group
included individuals without depressive symptoms in any of the 3 waves (2010, 2013, and 2016). The
delayed onset group included people who did not report depressive symptoms in 2010 or 2013 but
developed symptoms by 2016. The recovered group consisted of individuals who reported
significant depressive symptoms (ie, Geriatric Depression Scale score of ⱖ5) in 2010 and/or 2013 but
did not report them (ie, Geriatric Depression Scale score of ⱕ4) in 2016, ie, their symptoms had
remitted. The persistent group included those reporting depressive symptoms at least once in 2010or 2013 as well as in 2016, meaning that this group included those with depressive symptoms in 2010
and 2016, in 2013 and 2016, and in 2010, 2013, and 2016.

Statistical Analysis
First, we examined the overall community prevalence of mental illness symptoms at each survey.
Then we described the within-individual trajectories of PTSS across the 2 waves and depressive
symptoms across the 3 waves. We conducted paired t tests to examine the statistical significance inthe prevalence of mental illness symptoms.
We imputed the missing values of covariates through the Markov chain Monte Carlo methods
using mi command in Stata. We created 20 imputed data sets and used the mi estimate command to
estimate model parameters from multiply imputed data. All the analyses were performed using Stata
version 15 (StataCorp) from October 2019 to February 2020. Statistical significance was set at
P < .05, and all tests were 2-tailed.

Box. Questions to Measure Posttraumatic Stress Symptoms (PTSS) and Depressive Symptoms
The Screening Questionnaire for Disaster Mental
Health–9 items for PTSS

Have you dropped many of your activities andinterests?

Do you have trouble falling asleep or sleeping
through the night?

Do you feel that your life is empty?

Do you have nightmares about the event?

Are you in good spirits most of the time?aDo you feel irritable?

Are you afraid that something bad is going tohappen to you?

Do you feel that you are hypersensitive to small
noises or tremors?
Do you avoid places, people, topics related tothe event?
Do you think about the event when you do notwant to?
Do you have trouble enjoying things you used
to enjoy?
Do you get upset when something reminds you ofthe event?
Do you notice that you are making an effort to try
not to think about the event, or are trying toforget it?
The Geriatric Depression Scale Short Form–15
items

Do you often get bored?

Do you feel happy most of the time?aDo you often feel helpless?
Do you prefer to stay at home, rather than going out
and doing new things?
Do you feel you have more problems with memory
than most?
Do you think it is wonderful to be alive now?aDo you feel pretty worthless the way you are now?
Do you feel full of energy?a
Do you feel that your situation is hopeless?
Do you think that most people are better off than
you are?

Are you basically satisfied with your life?aaThese questions were reverse coded, ie, a lower score indicated more severe depressive symptoms.

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Results
The analytic samples for trajectories of PTSS (from 2013-2016) and depressive symptoms (from2010-2016) included 2275 and 1735 respondents, respectively (Figure 1). The Table exhibits thecharacteristics of the samples for each analysis. At baseline, there were slightly more women (1262
of 2275 [55.5%] and 882 of 1735 [50.8%]), and most participants were aged 65 to 74 years (1533[67.4%] and 1224 [70.5%]) and married (1664 [76.2%] and 1319 [77.7%]). Nearly 70% had more than
9 years of schooling (1550 [68.8%]) and 1205 [70.0%]), and most had equivalized household incomeof ¥200 million or more (ⱖ$1 869 050) (1381 [52.8%] and 1054 [54.7%]).

Trends in Community Prevalence of Mental Illness
Figure 2 presents the trends in community prevalence of PTSS and depressive symptoms in
Iwanuma from 2010 (before the disaster) to 2016 (5 years after the disaster). The prevalence ofpeople with depressive symptoms was remarkably stable between 2010 and 2016 (approximately

Table. Demographic Characteristics of Analytic Sample
Participants, No (%)
Characteristic

For PTSS trajectory (n = 2275)

For DEP trajectory (n = 1735)

Men

1013 (44.5)

853 (49.2)

Women1262 (55.5)

882 (50.8)

65-741533 (67.4)

1224 (70.5)≥75742 (32.3)

511 (29.5)≤9710 (31.2)

514 (30.0)>91550 (68.8)

1205 (70.0)<200

894 (47.2)

681 (45.3)≥2001381 (52.8)

1054 (54.7)

Single542 (23.8)

387 (22.3)

Married1664 (76.2)

1319 (77.7)

Never1913 (84.1)

962 (55.4)

Delayed109 (4.8)

101 (5.8)

Recovered147 (6.5)

268 (15.4)

Persistent

106 (4.7)

404 (23.3)

Sex

Baseline age, y

Education, yBaseline equivalized income, millions of ¥Baseline marital status

Trajectory group

Abbreviations: DEP, depressive symptoms; PTSS,
posttraumatic stress symptoms.

Figure 2. Prevalence of Posttraumatic Stress Symptoms (PTSS) and Depressive Symptoms
3530

Prevalence, %25
Depressive symptoms
PTSS

20
15
10
5
0
2010

2013

2016

Year

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Error bars indicate 95% CIs.

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JAMA Network Open | PsychiatryLong-term Trends in Mental Health Disorders After the 2011 Great East Japan Earthquake and Tsunami29%), which was statistically confirmed (2010 vs 2013, 504 [29.0%] vs 506 [29.2%]; P = .91; 2013vs 2016, 506 [29.2%] vs 505 [29.1%]; P = .96). The prevalence of PTSS declined from 2013 to 2016,
from 253 (11.1%) to 215 (9.5%) (P = .02). Combining the prevalence of depressive symptoms andPTSS, approximately 40% of survivors were experiencing significant mental health symptoms (PTSSor depressive symptoms) more than 5 years after the disaster. However, this observation is temperedby the fact that the prevalence of depressive symptoms was already quite high before the disaster(504 [29.0%]), so we cannot attribute most of the excess mental illness symptoms to the disaster.

Within-Individual Trajectories of Mental Illness Symptoms
Figure 3 summarizes the within-individual trajectories of PTSS and depressive symptoms between
2010 and 2016. Overall, there was a 13.6% (95% CI, 11.7%-15.6%) incidence of depression amongpeople who did not have depression before the disaster (n = 168). However, among 504 people whoreported significant depressive symptoms before the disaster, 166 (32.9%) experienced symptom
remission by 2013. Between 2013 and 2016, a further 165 people remitted, while 164 people
experienced delayed onset of depression. Among those with preexisting depressive symptoms atbaseline in 2010, 338 (67.1%) had persistent depressive symptoms in 2013, and more than half had
persistent depressive symptoms in 2013 and 2016 (258 [51.2%]). By 2016, 85 of 168 participants(50.6%) who first reported depressive symptoms in 2013 had recovered.
A total of 253 survivors (11.1%; 95% CI, 9.8%-12.4%) reported serious PTSS in 2013, of whom
106 (41.9%) still had PTSS in 2016, while 147 (58.1%) had recovered by 2016. Of 2022 with no PTSS
in 2013, 109 (5.3%) had developed symptoms by 2016. We compared the prevalence of PTSS in 2013(11.1%) and in 2016 (9.5%) and found that null hypothesis was rejected with a P = .02 from a 2-tailed
paired t test. Therefore, we concluded that the prevalence of PTSS in 2013 was statistically associatedwith its prevalence in 2016. Overall, 1913 participants (84.1%) did not have PTSS either in 2013 or2016. We also conducted a sensitivity analysis to examine the prevalence of PTSS only among thosewith information on depressive symptoms. We found that 163 out of 1686 (9.7%) in 2013 and 127 of
1583 (8.0%) in 2016 had PTSS, indicating a similar trend as our main findings. In addition, to consider
selection bias owing to missing data, we conducted inverse-probability weighting as a sensitivity
analysis. We found that the prevalence of depressive symptoms was 29.5% (95% CI, 27.3%-31.7%)
in 2010, 29.6% (95% CI, 27.4%-31.8%) in 2013, and 29.2% (95% CI, 27.0%-31.4%) in 2016 and the

Figure 3. Trajectories of Posttraumatic Stress Symptoms (PTSS) Among 2275 Participants andDepressive Symptoms (DEP) Among 1735 Participants
2013

253 PTSS

2022 No PTSS

2013

106 PTSS

147 No PTSS

109 PTSS

1913 No PTSS

Trajectorygroups

106 Persistent (4.7%)

147 Recovered (6.5%)

109 Delayed (4.8%)

1913 Never (84.1%)

2010

2013

2013
Trajectorygroups504 DEP338 DEP

258 DEP

80 No DEP

404 Persistent (23.3%)

1231 No DEP

166 No DEP

63 DEP

103 No DEP

268 Recovered (15.4%)

168 DEP

83 DEP

85 No DEP

101 Delayed (5.8%)

1063 No DEP

101 DEP

962 Never (55.4%)

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prevalence of PTSS was 11.1% (95% CI, 9.7%-12.4%) in 2013 and 9.2% (95% CI, 8.0%-10.4%) in 2016.
These findings are in line with our main findings.

Discussion
The mental health of survivors of a traumatic event, such as a natural disaster, has been extensively
studied.22 However, owing to the lack of predisaster information, very few studies have been able totease out the consequences of disaster exposure from preexisting conditions. In this study, we
examined the community-level prevalence of mental health disorders as well as the within-individual
trajectories of depressive symptoms and PTSS following the 2011 Great East Japan earthquake andtsunami. We have previously reported13,14 that personal exposure to trauma (loss of relatives,
housing damage) was associated with new onset depressive symptoms and PTSS. In contrast tothese individual experiences, from a community-wide perspective, we found little evidence in thepresent study of an epidemic of depressive symptoms after the disaster.
There are 3 possible reasons for the apparent stability in the prevalence of depression between
predisaster to postdisaster surveys. First, the prevalence of depressive symptoms was already highin this community before the disaster (29%). Although this figure seems high, our data are consistent
with previous studies among older Japanese populations using the same instrument and the same
cutoff point (eg, Wada et al23 reported 33.5% and Sasaki et al24 reported between 21.5% and 36.2%).
Interestingly, in the absence of predisaster information, researchers might have been tempted toconclude that the high prevalence of depression in the community was attributable to the traumatic
experiences associated with the disaster. The second reason why the community prevalence ofdepressive symptoms appeared to be stable over time is because even though 13.6% of residents
experienced new onset of depression after the disaster, this was offset by individuals who weredepressed before the disaster but whose symptoms had remitted by follow-up. A third possible
explanation for the stability of the prevalence of depression may be due to posttraumatic growth thatsome individuals experience after a disaster.25 For example, some reports suggest that people may
become more socially active following disaster experiences and that increased social capital might
promote improved mental resilience.26
There are 2 caveats to this interpretation. First, we did not observe the immediate
consequences of the disaster in the very short term (eg, within the first year), during which people
were more likely to suffer from acute grief and distress given the fact that the first year after adisaster is the peak of psychological symptoms.11 Second, there may have been some selective
attrition of individuals who were depressed before the disaster. In a previous report, we found that
individuals who were severely depressed on the day of the earthquake and tsunami were twice as
likely to lose their life, possibly as a result of delayed evacuation.27 The selective mortality of these
individuals would tend to underestimate the true counterfactual prevalence of depression in thecommunity after the disaster. On the other hand, the consequence of this bias is likely to be small,given that a total of 34 of the baseline sample of 4857 participants died (yielding a 0.69% mortality
rate on the day of the disaster).
Regarding PTSS, we found that approximately 60% of people who reported PTSS in 2013 hadrecovered by 2016. This is consistent with the findings of the meta-analysis among natural disastersurvivors by Morina et al.3
When the figures for depressive symptoms and PTSS are combined, our data suggest thatnearly 40% of survivors were still experiencing significant mental health symptoms (PTSS ordepressive symptoms) more than 5 years after the disaster. While this figure presents a scenario of
persistent, long-term mental health problems in the wake of the disaster, much of it cannot be
attributed to the disaster trauma given that nearly one-third of the sample reported significant
depressive symptoms preceding the March 11, 2011, event. In other words, we did not find evidenceof a community-wide epidemic of mental illness following a major disaster.

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Strengths and Limitations
The major strength of this study was that we collected the baseline mental health data before thedisaster. As Galea et al4 have argued, study designs featuring only postdisaster assessments areunable to distinguish between mental health consequences of disaster vs the persistence ofpredisaster conditions. Our 3-wave analysis also allowed us to examine the within-individual
trajectories of mental illness symptoms during a longer period than in most previous studies.
There are some limitations of our study. First, the response rate at the baseline survey was
59.0%, which is quite similar compared with other community-dwelling surveys. Furthermore, thecharacteristics of the baseline sample were very similar to 2010 National Census population in thearea.14 The response rates at follow-up surveys were very high (82.1% and 84.6% for the 2 follow-up
survey waves, respectively). Second, there might be a chance of selection bias due to loss tofollow-up during 3 years. People who were most depressed or had severe PTSS were more likely tohave dropped out, which could potentially inflate the recovery rates. However, our sensitivity
analysis showed similar results as our main findings.

Conclusions
In this study, approximately 40% of survivors from the Great East Japan earthquake and tsunami still
experienced PTSS or depressive symptoms or both 5.5 years after the disaster. However, the mental
resilience at the community level was remarkably stable, suggesting that the community itself wasresilient.

ARTICLE INFORMATION
Accepted for Publication: May 26, 2020.
Published: August 14, 2020. doi:10.1001/jamanetworkopen.2020.13437
Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2020 Kino S et al.
JAMA Network Open.
Corresponding Author: Shiho Kino, PhD, Harvard T.H. Chan School of Public Health, Department of Social and
Behavioral Sciences, 401 Park Dr, West Fourth Floor, Boston, MA 02215 (shkino@hsph.harvard.edu).
Author Affiliations: Harvard T.H. Chan School of Public Health, Department of Social and Behavioral Sciences,
Boston, Massachusetts (Kino, Kawachi); Tohoku University Graduate School of Dentistry, Department ofInternational and Community Oral Health, Sendai, Japan (Aida); Chiba University, Center for Preventive Medical
Sciences, Chiba, Japan (Kondo); Department of Gerontological Evaluation, Center for Gerontology and Social
Science, National Center for Geriatrics and Gerontology, Aichi, Japan (Kondo).
Author Contributions: Drs Kino 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: Kino, Kawachi.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Kino, Aida.
Critical revision of the manuscript for important intellectual content: Kondo, Kawachi.
Statistical analysis: Kino.
Obtained funding: Aida, Kondo, Kawachi.
Administrative, technical, or material support: Kondo.
Supervision: Kawachi.
Conflict of Interest Disclosures: Dr Kondo reported receiving grants from the NEC Corp, grants from Resol Seimei
No Mori, and Ryobi Systems outside the submitted work. No other disclosures were reported.
Funding/Support: This work was supported by grant R01 AG042463 from the National Institutes of Health;grants KAKENHI 15H01972, KAKENHI 23243070, KAKENHI 22390400, KAKENHI 22592327, and KAKENHI
24390469 from the Japan Society for the Promotion of Science; grants H22-Choju-Shitei-008, H24-ChojuWakate-009, and H28-Chouju-Ippan-002 from the Japanese Ministry of Health, Labour and Welfare; and grant

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S0991035 from the Strategic Research Foundation Grant-Aided Project for Private Universities from the Japanese
Ministry of Education, Culture, Sports, Science and Technology.
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.
Additional Contributions: We appreciate the support and cooperation of the Iwanuma Mayor’s office, the staff ofthe Department of Health and Welfare of Iwanuma city government, and the cooperation of the Iwanuma Study
participants.
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