Yonago Acta medica 2014;57:73–83

Original Article

Psychological Factors and Mortality Risk in a Rural Area of Japan
Yasuko Tokushima,* Takenobu Hosoda,† Mikizo Okamoto† and Youichi Kurozawa†*Department of Nursing Care Environment and Mental Health, School of Health Science, Tottori University Faculty of Medicine,
Yonago 683-8503, Japan and †Division of Health Administration and Promotion, Department of Social Medicine, School of Medicine,
Tottori University Faculty of Medicine, Yonago 683-8503, Japan

ABSTRACT

To our knowledge, there is no equivalent term in English. Ikigai is defined in Japanese dictionaries as something to live for, the joy and goal of living, a life worth
living, and the happiness and benefit of being alive. It isalso understood to be a comprehensive concept including not only pleasure and happiness but also the meaning of one’s life and self-realization.2, 3 In the present
study, we defined ikigai as “that which most makes one’s
life seem worth living” and defined persons with ikigai
as those with a positive sense of psychological well-being. Previous studies1–9 suggested that lack of ikigai wasassociated with increased mortality risk from all causes.
Psychological stress is considered to be associated withincrease risks for disease, especially for cardiovasculardisease.15–18 Time urgency is also one of components of
the Type A behavior pattern, but there is little information on the association of time urgency with mortality
risk.19 Information on the association time urgency withmortality is also little.1
Only 2 investigations1, 4 have looked at the relationship between the feeling of being trusted and mortality
risk. These studies suggested that in those who had no
feeling of being trusted, mortality risk of all causes increased. However, the adjusted confounding factors wereless in both studies. Tanno and Sakata1 adjusted for age
and residence of confounding factors the subject. Sakata
et al.4 adjusted age, smoking status, drinking status andpast hypertension.
The purpose of the present study is to assess the association between psychological factors and mortality
risk from all causes. This research attempted to clarify
the level of influence of various psychological factors
after multivariate adjustment on mortality risk from allcauses, on the basis of a long-term cohort study.

Background

The purpose of this study is to assess theassociation between psychological factors and mortality
risk from all causes.
Methods We used follow-up data for 4,181 persons
from 40 to 79 years over a period of 17.6 years from onepart of the Japan Collaborative Cohort Study (JACC
Study). The status of the individuals comprising the dataof the study as of the end of December 2006 was determined from their registration cards and death records.
We calculated the proportions of selected variables
among 5 psychological factors by sex. Cox’s proportional hazards model was used to evaluate the associations
between psychological factors and mortality risk fromall causes. Data were adjusted for age, medical history,
education, job status, marital status, drinking, smoking,physical activity, sleeping duration, body mass index andbreakfast.
Results
During the follow-up period, a total of 791
deaths were recorded. Men who reported feelings of being trusted had a decreased risk for mortality risk fromall causes compared with the risk of those who reported“maybe”, whereas those without feelings of being trusted
had increased risk for mortality risk from all causes.
Conclusion This study suggests that the absence offeelings of being trusted increases the risk of all causesof mortality among middle-aged and elderly men in arural area. Our findings suggest that interpersonal relationships comprise an important factor in longevity.
Key words

feeling of being trusted; long-term cohort
study; mortality risk; psychological factor; survival
analysisSome previous studies have suggested that positive psychological factors, such as well-being, life satisfaction
and optimism, contribute to reduction of mortality risk
from all causes.1–14 In Japan, ikigai is a Japanese wordthat is considered to express one’s personal well-being.1

SUBJECTS AND METHODS
The present study began in 1989 in Nichinan Town, an
agricultural community located in the southwest area of
Tottori Prefecture. About 90% of the town is forest. The
birth rate is low while longevity progresses.20 The mainindustries of the town are agriculture and construction
accounting for about 50% of the economy of the town,
the local labor force being mainly engaged in these occupations. At that time, the town had a total population

Corresponding author: Yasuko Tokushima
y-tokushima@med.tottori-u.ac.jp
Received 2013 December 6
Accepted 2014 January 29
Abbreviations: BMI, body mass index; HR, hazard ratio; JACC
Study, the Japan Collaborative Cohort Study73

Y. Tokushima et al.

of 7,943, of whom 26.3% aged 65 years or older. By
2005, because of the steadily declining birth rate and aging, the town population had decreased to 44.9% of the
1989 level according to the national census.21
We used 17.6-year follow-up data (1,979 men and
2,430 women from 40 to 79 years) from one area of theJapan Collaborative Cohort Study (JACC Study).11, 12, 22,
23
The status of the individuals comprising the data of
the study at the end of December 2006 was determinedfrom their registration cards and death records. To conserve personal information, the names of all individuals
were coded. Privacy concerns were noted and the study
was approved by the Ethics Committee of Tottori University (approval number, 1380).

The group of “maybe yes” was defined as the referencegroup.
The responses related to medical history (stroke, hypertension, myocardial infarction, kidney disease, liverdisease, cholecystitis or cholelithiasis, diabetes mellitus,
gastric ulcer or duodenal ulcer, tuberculosis or pleurisy
or cancer) were classified into 2 categories: “yes” or “no.”Alcohol use status was classified into 3 categories: “current drinker,” “past drinker” or “non-drinker.” Smoking status was also classified into 3 categories: “current
smoker,” “past smoker” or “non-smoker.” Physical activity was classified into 2 categories: “exercise ≥ 1 h/week”
or “exercise rarely.” Sleep duration was classified into 3
categories: “< 7 h,” “≥ 7 h and < 9 h,” “≥ 9 h.” BMI wasclassified into 3 categories: “< 18.5,” “≥ 18.5 and < 25,”“≥ 25.” Breakfast was classified into 2 categories: “I eat”
and “I rarely eat.”
About social factors, education was classified into 2
categories: “age at graduation of < 18 years” or “higher
age at final graduation.” Job was classified into 3 categories: “unemployed” (including “housewife”), “employee”(including “office worker” and “self-employed”) or“farmer” (including “contracted worker”). Marital status
was classified into 2 categories: “living with a spouse” or“other” (single, divorced or widowed).

Survey items and classifications

The baseline survey contents in 1989 were elicited by
self-administered questionnaire: medical history (stroke,
hypertension, myocardial infarction, kidney disease,liver disease, cholecystitis or cholelithiasis, diabetes
mellitus, gastric ulcer or duodenal ulcer, tuberculosis or
pleurisy or cancer), eating habits, movement, rest, healthcondition, psychological condition, drinking habit,smoking habit, height, weight, marriage history, school
education and occupation. In the present study, we used
the following items out of the above; psychological factors, medical history, alcohol use status, smoking status,
physical activity, sleep duration, body mass index (BMI),
breakfast, education level, job status and marital status.
Psychological factors involved getting data on “ikigai,”“psychological stress,” “sense of hurry,” “a feeling of being trusted” and “life satisfaction.” Ikigai was assessed
through the subject’s response to the question “Do you
have ikigai in your life?” We classified the items related
to ikigai into 2 categories by combining positive answers
such as “definitely yes” and “yes” into one category andnegative answers such as “maybe yes” and “unknown”
into the other because the answers are similar. The negative category formed the reference group for ikigai.
Psychological stress was assessed through the subject’s response to the question “Do you feel stress during your daily life?” The sense of hurry was assessed
through the subject’s response to the question “Do you
hurry to complete your daily work?” The feeling of being trusted was assessed through the subject’s responseto the question “Do you feel you are trusted by someone?” Life satisfaction was assessed through the subject’s response to the question “Do you wish you could
live your life over again?” We classified answers to these4 items into 3 categories by combining positive answers
such as “definitely yes” and “yes” into one category, negative answers such as “no” and “maybe yes” to another.

Statistical analysis

We excluded 227 persons who died within 5 years after
the study began. As for persons transferring, the period
to transfer was analyzed as a pursuit period. We calculated the proportions of the selected variables for the
5 psychosocial factors by sex at baseline. The abovementioned categorical variables were compared usinga chi-squared test between each psychological factor bysex. We calculated Spearman’s correlation coefficientfor each psychological factor at baseline. Cox’s proportional hazards model was used to evaluate the associations between each psychological factor and mortality
risk from all causes. Data were adjusted for age, medical
history, education, job status, marital status, drinking
status, smoking status, physical activity, sleep duration,
BMI and breakfast by sex. We used IBM SPSS Statistics
Ver.19 (IBM, Chicago, IL) for analysis.
RESULTS
During the follow-up period (average 15.7 years; total
65,660.5 person years), a total of 791 deaths (482 men
and 309 women) were recorded. Tables 1 to 5 show selected baseline characteristics of the subjects according
to the psychological factors by sex. Each psychologicalfactor was observed significant differences mutually.
The relations with items other than psychological factors
74

Psychological factors and mortality risk
Table 1. Selected baseline characteristics of the subjects according to ikigai by sex

Age, yr

Medical history
Drinking status
Smoking status
Physical activity
Sleep duration, h
BMIBreakfast
Education
Job status
Marital status
PsychologicalstressSense of hurry
Feeling of
being trusted
Life satisfaction

40–49
50–59
60–69
70–79
Absence
Existence
Never
Past
Current
Never
Past
Current
Exercise rarely
Exercise ≥ 1 h/week≥ 7 and < 9<7≥9≥ 18.5 and < 25
< 18.5≥ 25
Eat rarelyEat
Age at graduation of < 18 years
Higher age at final graduation
Unemployed
Employed-worker or self-employed worker
FarmerSingle, divorced or widowed
Living with a spouse
Maybe yes
Definitely yes or yes
No
Maybe yes
Definitely yes or yes
No
Maybe yes
Definitely yes or yes
No
Maybe yes
Definitely yes or yes
No

IkigaiMen				Maybe yes
Definitely yesor unknown or yes
n
(%)
n
(%)

Women
Maybe yesor unknownn(%)

Definitely yesor yesn(%)

156 (47.1)
322 (55.6)
280 (52.0)
138 (60.0)
304 (49.6)
238 (54.0)
154 (58.8)
86 (61.9)647 (51.5)
205 (50.2)
234 (55.2)
434 (53.4)
689 (55.6)
149 (43.2)
604 (52.0)
153 (51.5)
115 (62.5)
648 (52.1)
46 (64.8)
139 (51.7)
88 (57.1)
808 (53.0)
553 (53.2)
263 (54.6)
176 (66.2)
351 (47.4)
300 (52.4)
76 (69.1)
624 (49.8)
598 (56.0)
203 (50.2)
79 (44.1)
418 (59.5)
378 (45.3)
85 (70.2)593 (54.9)
71 (24.7)
222 (76.0)
441 (58.8)
104 (28.8)
329 (62.4)

248 (62.5)
483 (66.1)
459 (72.5)240 (71.0)
558 (66.0)
264 (68.4)
939 (69.5)
25 (73.5)271 (60.0)1140 (67.4)
20 (74.1)
40 (72.7)
1151 (69.3)
151 (62.1)
923 (67.9)
367 (64.4)
98 (84.5)
969 (67.2)
69 (69.0)276 (68.5)
155 (68.0)1275 (68.1)
844 (68.8)
467 (67.5)
602 (71.4)
480 (63.8)
180 (65.5)
224 (73.4)
884 (65.6)
949 (69.3)
316 (70.7)
108 (50.0)
719 (74.0)
570 (61.0)
121 (70.3)
910 (69.3)
102 (38.9)374 (79.4)
632 (71.7)
138 (44.2)
616 (72.6)

149 (37.5)*
248 (33.9)
174 (27.5)
98 (29.0)
287 (34.0)
122 (31.6)
412 (30.5)**
9 (26.5)181 (40.0)552 (32.6)
7 (25.9)15 (27.3)
511 (30.7)*
92 (37.9)
437 (32.1)**
203 (35.6)
18 (15.5)474 (32.8)
31 (31.0)
127 (31.5)
73 (32.0)596 (31.9)
382 (31.2)
225 (32.5)
241 (28.6)*
272 (36.2)
95 (34.5)
81 (26.6)*
463 (34.4)
421 (30.7)**
131 (29.3)
108 (50.0)
252 (26.0)**365 (39.0)
51 (29.7)
403 (30.7)**
160 (61.1)
97 (20.6)
249 (28.3)**
174 (55.8)
233 (27.4)

175 (52.9)*257 (44.4)
258 (48.0)
92 (40.0)309 (50.4)
203 (46.0)
108 (41.2)*
53 (38.1)
610 (48.5)
203 (49.8)
190 (44.8)
379 (46.6)
550 (44.4)**
196 (56.8)
557 (48.0)*
144 (48.5)
69 (37.5)
595 (47.9)
25 (35.2)
130 (48.3)
66 (42.9)716 (47.0)
486 (46.8)
219 (45.4)
90 (33.8)**389 (52.6)
273 (47.6)
34 (30.9)**629 (50.2)
470 (44.0)*
201 (49.8)
100 (55.9)
284 (40.5)**457 (54.7)
36 (29.8)487 (45.1)**
217 (75.3)
70 (24.0)313 (41.2)**
257 (71.2)
198 (37.6)

BMI, body mass index.
*P < 0.05.
**P < 0.001.

are shown below. As for ikigai, significant differenceswere observed in the category of age, drinking status,
physical activity, sleep duration, job status and marital
status among men and women (Table 1). As for psychological stress, the same results as ikigai among women(Table 2). As for sense of hurry, significant differenceswere observed in the category of age, drinking status,
job status and marital status among men and women(Table 3). As for feeling of being trusted, there was no

significant difference in the category of age among both
men and women (Table 4). As for life satisfaction, significant differences were observed in the category of age
and job status among men and women (Table 5). There
were observed significant differences between 5 psychological factors and job status among men and women.
Only among women, significant differences were observed between 5 psychological factors and marital
status. Table 6 shows correlation coefficients between
75

Y. Tokushima et al.
Table 2. Selected baseline characteristics of the subjects according to psychological stress by sex
Psychological stressMen						 Women
Maybe
Definitely 			
Maybe
yes		
yes or yes
No		
yes		
n (%)
n (%)
n (%)
n (%)
Age, yr

Medical history
Drinking status
Smoking status
Physical activity
Sleep duration, h
BMIBreakfast
Education
Job status

Marital status
Ikigai
Sense of hurry
Feeling of
being trusted
Life satisfaction

40–49
190 (57.1)
50–59
371 (63.6)
60–69
371 (69.3)
70–79
159 (69.1)
Absence395 (64.1)
Existence
285 (64.0)
Never
179 (68.1)
Past
86 (62.8)
Current
814 (64.7)
Never
268 (65.7)
Past
275 (64.6)
Current
524 (64.7)
Exercise rarely
794 (64.0)
Exercise ≥ 1 h/week
228 (66.1)≥ 7 and < 9753 (64.8)<7
182 (61.1)≥9128 (70.3)≥ 18.5 and < 25
823 (66.1)< 18.546 (64.8)≥ 25
164 (60.1)
Eat rarely
99 (63.9)
Eat
992 (65.0)
Age at graduation of < 18 years 676 (64.4)
Higher age at final graduation 310 (64.7)
Unemployed
182 (68.4)
Employed-worker or
470 (63.1)
self-employed worker
Farmer367 (64.7)
Single, divorced, or widowed
70 (65.4)
Living with a spouse
798 (63.7)
Maybe yes or unknown
598 (68.0)
Definitely yes or yes
470 (61.0)
Maybe yes
523 (74.4)
Definitely yes or yes
489 (58.4)
No
69 (57.5)
Maybe yes
747 (69.0)
Definitely yes or yes
156 (53.6)
No
175 (60.6)
Maybe yes
531 (70.8)
Definitely yes or yes
227 (62.4)
No
305 (57.4)

Definitely
yes or yes
n (%)

No
n (%)

117 (35.1)
166 (28.5)
97 (18.1)
28 (12.2)
147 (23.9)
120 (27.0)
49 (18.6)
34 (24.8)319 (25.3)
91 (22.3)
100 (23.5)
210 (25.9)
322 (26.0)
69 (20.0)279 (24.0)
91 (30.5)
31 (17.0)
289 (23.2)
16 (22.5)
80 (29.3)
42 (27.1)
366 (24.0)
255 (24.3)
123 (25.7)
47 (17.7)

26 (7.8)** 236 (58.7)
46 (7.9)507 (69.0)
67 (12.6)451 (70.9)
43 (18.7)
229 (69.0)
74 (12.0)582 (68.2)
40 (9.0)254 (65.5)
35 (13.3)
960 (70.8)
17 (12.4)
19 (55.9)
126 (10.0)
260 (57.1)
49 (12.0) 1134 (67.0)
51 (11.9)
20 (74.1)
76 (9.4)
31 (54.4)
124 (10.0)* 1123 (66.8)
48 (13.9)
166 (69.5)
130 (11.2)
957 (69.8)
25 (8.4)353 (62.0)
23 (12.7)
74 (64.9)
133 (10.7)
964 (66.7)
9 (12.7)
70 (69.3)
29 (10.6)
280 (68.3)
14 (9.0)147 (64.2)
168 (11.0)
1276 (68.0)
118 (11.3)
850 (69.2)
46 (9.6)455 (65.4)
37 (13.9)* 593 (70.8)

137 (34.1)
164 (22.3)
113 (17.8)
39 (11.7)
177 (20.8)
100 (25.8)
259 (19.1)
9 (26.5)
137 (30.1)
369 (21.8)
4 (14.8)
21 (36.8)
383 (22.8)
38 (15.9)
268 (19.5)
160 (28.1)
15 (13.2)
318 (22.0)
19 (18.8)
88 (21.5)
54 (23.6)
399 (21.3)
244 (19.9)
169 (24.3)
138 (16.5)

29 (7.2)**
64 (8.7)
72 (11.3)
64 (19.3)
94 (11.0)
34 (8.7)
136 (10.1)**
6 (17.6)
58 (12.8)
189 (11.2)
3 (11.1)
5 (8.8)174 (10.4)*
35 (14.6)
146 (10.7)**
56 (9.9)25 (21.9)
163 (11.3)
12 (11.9)42 (10.2)
28 (12.2)
201 (10.7)
134 (10.9)
72 (10.3)
107 (12.7)**

195 (26.2)

80 (10.7)488 (64.4)

195 (25.7)

75 (9.9)

189 (66.8)
181 (59.7)
927 (68.7)
949 (69.1)
421 (63.8)
739 (76.0)
576 (61.5)
96 (55.2)
949 (71.6)
147 (55.9)
289 (61.8)
644 (73.3)
220 (70.1)
521 (60.9)

75 (26.5)
70 (23.1)
300 (22.2)
316 (23.0)
131 (19.8)
136 (14.0)
288 (30.8)
25 (14.4)
260 (19.6)
79 (30.0)106 (22.6)
157 (17.9)
38 (12.1)
250 (29.2)

19 (6.7)
52 (17.2)**
122 (9.1)
108 (7.9)**108 (16.4)
98 (10.0)**72 (7.7)
53 (30.4)
116 (8.8)**37 (14.1)
73 (15.6)
77 (8.8)**
56 (17.8)
85 (9.9)147 (25.9) 53 (9.4)
20 (18.7)
17 (15.9)322 (25.7) 132 (10.6)
203 (23.0) 79 (9.0)*
201 (26.0) 100 (13.0)
101 (14.4) 79 (11.2)**
280 (33.5) 68 (8.1)
22 (18.3) 29 (24.2)
223 (20.6) 112 (10.4)**
102 (35.1)
33 (11.3)
79 (27.3) 35 (12.1)
152 (20.3) 67 (8.9)**
83 (22.8) 54 (14.8)
167 (31.5) 59 (11.1)

BMI, body mass index.
*P < 0.05.
**P < 0.001.

Ikigai

psychological factors by sex. Correlations were foundamong each of the psychological factors, but the strengthof the association was weak.
Table 7 shows the age-adjusted and multivariate-adjusted hazard ratios (HRs) and 95% confidence levels of
all causes mortality risk according to the 5 psychologicalfactors among men, and Table 8 shows among women,in each follow-up period.

For men who reported “definitely yes” or “yes” in response to the question of whether they had ikigai, theirrisk for mortality from all causes after adjusting for age,the multivariate statistic (age-adjusted HR = 0.64, multivariate HR = 0.76) decreased compared with that for
men who reported “maybe” or “no.” However, the riskadjusted multivariate HR was not significant (P > 0.05).
76Psychological factors and mortality risk
Table 3. Selected baseline characteristics of the subjects according to sense of hurry by sex
Sence of hurry
Men						 Women
Maybe
Definitely 			
Maybe
yes		
yes or yes
No		
yes		
n (%)
n (%)
n (%)
n (%)
Age, yr

Medical history
Drinking status
Smoking status
Physical activity
Sleep duration, h
BMIBreakfast
Education
Job status

Marital status
Ikigai
PsychologicalstressFeeling of
being trusted
Life satisfaction

40–49
142 (42.9)
50–59
231 (39.4)
60–69
246 (45.1)
70–79
105 (44.9)
Absence
266 (43.0)
Existence
186 (41.7)
Never
127 (48.1)
Past
62 (44.6)
Current
527 (41.4)
Never
180 (44.1)
Past
184 (43.0)
Current
341 (41.4)
Exercise rarely
521 (41.9)
Exercise ≥ 1 h/week
146 (42.2)≥ 7 and < 9503 (43.1)<7
118 (39.3)≥9
82 (43.4)≥ 18.5 and < 25
532 (42.6)< 18.533 (45.2)≥ 25
112 (40.9)
Eat rarely
69 (44.8)
Eat655 (42.4)
Age at graduation of < 18 years 457 (43.2)
Higher age at final graduation 194 (40.1)
Unemployed
118 (44.7)
Employed-worker or
303 (40.3)
self-employed worker
Farmer251 (43.7)
Single, divorced or widowed
50 (46.3)
Living with a spouse
510 (40.4)
Maybe yes or unknown
418 (47.5)
Definitely yes or yes
284 (36.6)
Maybe yes
523 (48.4)
Definitely yes or yes
101 (25.1)
No
79 (44.9)
Maybe yes
492 (45.1)
Definity yes or yes
94 (32.1)
No
125 (43.1)
Maybe yes
318 (41.8)
Definitely yes or yes
156 (42.4)
No
231 (43.6)

Definitely
yes or yes
n (%)

No
n (%)

177 (53.5) 12 (3.6)**323 (55.0) 33 (5.6)
257 (47.2)
42 (7.7)
93 (39.7) 36 (15.4)
314 (50.8) 38 (6.2)
225 (50.4) 35 (7.9)
115 (43.6) 22 (8.3)*
61 (43.9)
16 (11.5)667 (52.4) 80 (6.2)
201 (49.3) 27 (6.6)
213 (49.8)
31 (7.2)
420 (51.0)
63 (7.6)623 (50.1) 99 (8.0)
181 (52.3) 19 (5.5)
590 (50.5) 75 (6.4)
159 (53.0) 23 (7.7)
86 (45.5) 21 (11.1)
628 (50.2) 90 (7.2)
31 (42.5)
9 (12.3)
148 (54.0) 14 (5.1)
81 (52.6)
4 (2.6)769 (49.8) 119 (7.8)
529 (50.0) 72 (6.8)
249 (51.4)
41 (8.5)
104 (39.4) 42 (15.9)**180 (44.4)
335 (44.7)
331 (50.7)
171 (49.1)
418 (48.5)
177 (45.2)
697 (50.3)
14 (41.2)
169 (36.6)
810 (47.0)
11 (40.7)
19 (32.8)
798 (46.8)
118 (48.4)
665 (47.7)
258 (44.4)
54 (45.4)
679 (46.1)
55 (51.4)
189 (45.8)
114 (47.5)
903 (47.1)
608 (48.2)
316 (44.5)
412 (48.1)

207 (51.2)
369 (49.2)
269 (41.2)
115 (33.0)
394 (45.7)
177 (45.2)
568 (41.0)
16 (47.1)
260 (56.3)
771 (44.7)
12 (44.4)
29 (50.0)765 (44.9)
104 (42.6)
629 (45.1)
271 (46.6)
43 (36.1)
690 (46.9)
40 (37.4)
180 (43.6)
111 (46.3)
849 (44.3)
555 (44.0)
325 (45.8)
333 (38.9)

18 (4.4)**
46 (6.1)
53 (8.1)
62 (17.9)
50 (5.8)*
38 (9.6)
120 (8.7)**
4 (11.7)
33 (7.1)
142 (8.3)
4 (14.9)
10 (17.2)
142 (8.3)
22 (9.0)101 (7.2)**
52 (9.0)22 (18.5)
103 (7.0)*
12 (11.2)
44 (10.6)
15 (6.2)
164 (8.6)
99 (7.8)
69 (9.7)
111 (13.0)**402 (53.5)

46 (6.2)

359 (46.6)

378 (49.1)

33 (4.3)

296 (51.6)
40 (37.0)
667 (52.9)
378 (42.9)
457 (58.8)
489 (45.2)
280 (69.5)
68 (38.6)
537 (49.2)
188 (64.2)
117 (40.3)
390 (51.4)
195 (53.0)
247 (46.6)

27 (4.7)
116 (40.7)
18 (16.7)** 129 (41.9)
84 (6.7)
631 (46.4)
85 (9.6)** 719 (51.0)
36 (4.6)
252 (37.7)
69 (6.4)** 739 (52.3)
22 (5.4)
136 (30.3)
29 (16.5)
98 (43.9)
63 (5.7)** 683 (50.7)
11 (3.7)
88 (33.2)
48 (16.6)
216 (44.8)
52 (6.8)*475 (53.0)
17 (4.6)
124 (38.9)
52 (9.8)383 (43.8)

153 (53.7)
16 (5.6)
131 (42.5) 48 (15.6)**632 (46.4) 98 (7.2)
570 (40.4) 121 (8.6)**
365 (54.6) 51 (7.7)
576 (40.8) 96 (6.9)**288 (43.1)
25 (26.6)
72 (32.3) 53 (23.8)
589 (43.7)
75 (5.6)**
166 (62.6) 11 (4.2)
179 (37.1)
87 (18.1)
365 (40.7) 57 (6.3)**
169 (53.0) 26 (8.1)
403 (46.1) 88 (10.1)

BMI, body mass index.
*P < 0.05.
**P < 0.001.

Sense of hurry

Women respondents showed no significant results (P >0.05) for any of the above adjustments.

Respondents who reported that they had a sense of hurryin completing their daily work had a reduced risk of mortality from all causes after adjusting for age (HR = 0.78)
compared with those who reported “maybe.” However,multivariate analyses were not significant (P > 0.05) inmen. In addition, there was no significant association (P >0.05) between sense of hurry and mortality risk from allcauses among women.

Psychological stressNo significant association was found between psychological stress and mortality risk from all causes for both
sexes across all of the adjustments described above.
77

Y. Tokushima et al.
Table 4. Selected baseline characteristics of the subjects according to feeling of being trusted by sex
Feeling of being trusted
Men						 Women
Maybe
Definitely 			
Maybe
yes		
yes or yes
No		
yes		
n (%)
n (%)
n (%)
n (%)
Age, yr

Medical history
Drinking status
Smoking status
Physical activity
Sleep duration, h
BMIBreakfast
Education
Job status

Marital status
Ikigai
PsychologicalstressSense of hurryLife satisfaction

40–49
216 (65.3)
50–59
380 (65.0)
60–69
362 (66.7)
70–79
143 (60.1)
Absence415 (67.6)
Existence
276 (62.0)
Never
159 (60.7)
Past
93 (66.4)
Current
837 (65.7)
Never
270 (66.2)
Past
273 (63.6)
Current
534 (65.0)
Exercise rarely
805 (64.8)
Exercise ≥ 1 h/week
229 (66.0)≥ 7 and < 9765 (65.4)<7
195 (65.4)≥9116 (61.0)≥ 18.5 and < 25
803 (64.2)< 18.546 (62.2)≥ 25
186 (68.4)
Eat rarely
103 (66.5)
Eat
998 (64.7)
Age at graduation of < 18 years 684 (65.1)
Higher age at final graduation 314 (64.1)
Unemployed
173 (63.6)
Employed-worker or
482 (64.3)
self-employed worker
Farmer366 (64.7)
Single, divorced or widowed
70 (64.2)
Living with a spouse
806 (63.9)
Maybe yes or unknown
593 (66.9)
Definitely yes or yes
487 (62.9)
Maybe yes
747 (69.3)
Definitely yes or yes
223 (55.2)
No
112 (62.2)
Maybe yes
492 (69.2)
Definitely yes, or yes
537 (63.8)
No
63 (51.6)
Maybe yes
533 (70.2)
Definitely yes or yes
225 (61.1)
No
319 (59.8)

Definitely
yes or yes
n (%)

No
n (%)

62 (18.7)
103 (17.6)
84 (15.5)45 (18.9)
108 (17.6)
94 (21.1)
44 (16.8)
25 (17.9)
222 (17.4)
69 (16.9)
81 (18.9)
138 (16.8)
202 (16.3)
75 (21.6)
215 (18.4)
56 (18.8)
18 (9.5)231 (18.5)
8 (10.8)47 (17.3)
29 (18.7)
265 (17.2)
185 (17.6)
83 (16.9)
31 (11.4)

53 (16.0)
261 (65.3)
102 (17.4)
469 (63.9)
97 (17.8)424 (65.1)
50 (21.0)
211 (62.4)
91 (14.8)570 (66.9)
75 (16.9)
242 (61.9)
59 (22.5)
904 (65.9)
22 (15.7)
15 (44.1)
215 (16.9)
293 (63.8)
69 (16.9)1111 (65.1)
75 (17.5)
17 (63.0)
150 (18.2)
26 (45.6)
235 (18.9)* 1069 (63.3)
43 (12.4)
163 (67.6)
190 (16.2)** 908 (65.6)
47 (15.8)345 (61.1)
56 (29.5)
74 (62.2)
216 (17.3)
937 (64.4)
20 (27.0)
72 (67.9)
39 (14.3)
258 (63.1)
23 (14.8)
143 (60.9)
279 (18.1)
1222 (64.7)
182 (17.3)
803 (64.7)
93 (19.0)440 (62.9)
68 (25.0)** 529 (62.5)

57 (14.3)
100 (13.6)
73 (11.2)
36 (10.7)
107 (12.6)
63 (16.1)
160 (11.7)
5 (14.7)
72 (15.7)
223 (13.1)
4 (14.8)
9 (15.8)
209 (12.4)
37 (15.4)
167 (12.1)
89 (15.8)
6 (5.0)182 (12.5)
11 (10.4)
62 (15.2)
27 (11.5)
239 (12.7)
161 (13.0)
90 (12.9)
96 (11.3)

82 (20.4)
165 (22.5)
154 (23.7)
91 (26.9)
175 (20.5)
86 (22.0)
307 (22.4)*
14 (41.2)
94 (20.5)373 (21.8)*
6 (22.2)
22 (38.6)
412 (24.3)*
41 (17.0)309 (22.3)*
131 (23.1)
39 (32.8)337 (23.1)
23 (21.7)
89 (21.7)
65 (27.6)
427 (22.6)
278 (22.3)
170 (24.2)
222 (26.2)*

158 (21.1)

110 (14.6)

494 (65.3)

111 (14.7)

152 (20.0)

97 (17.1)
10 (9.2)
254 (20.1)
71 (8.0)217 (28.0)
156 (14.5)
102 (25.2)
33 (18.3)
94 (13.2)
188 (22.3)
11 (9.0)106 (14.0)
116 (31.5)
68 (12.8)

103 (18.2)
29 (26.6)*201 (16.0)
222 (25.1)**
70 (9.1)
175 (16.2)**
79 (19.6)
35 (19.5)
125 (17.6)**
117 (13.9)
48 (39.4)
120 (15.8)**
27 (7.4)
146 (27.4)

189 (66.8)
176 (58.1)
881 (65.3)
910 (65.7)
403 (61.1)
949 (68.5)
260 (58.4)
116 (51.3)
683 (69.2)
589 (63.1)
75 (43.4)
613 (68.8)
216 (68.1)
502 (58.0)

35 (12.4)
28 (9.2)
193 (14.3)
102 (7.3)
160 (24.2)
147 (10.6)
79 (17.8)
37 (16.4)
88 (8.9)166 (17.8)
11 (6.4)
93 (10.4)
69 (21.8)
99 (11.4)

59 (20.8)
99 (32.7)**
275 (20.4)
374 (27.0)**
97 (14.7)
289 (20.9)**106 (23.8)
73 (32.3)
216 (21.9)**179 (19.1)
87 (50.2)
185 (20.8)**
32 (10.1)
265 (30.6)

BMI, body mass index.
*P < 0.05.
**P < 0.001.

Feeling of being trusted

Life satisfaction

Men who had feeling of being trusted had a decreased
mortality risk from all causes compared with those whoreported “maybe,” whereas in those who lacked the feelingof being trusted, mortality risk from all causes increased(age-adjusted HR = 1.59, multivariate HR = 1.67). However, there was no significant difference among women.

There was no significant association between feeling oflife satisfaction and mortality risk from all causes forboth sexes across all adjustments as described above.

78

Psychological factors and mortality risk
Table 5. Selected baseline characteristics of the subjects according to life satisfaction by sex
Life satisfaction
Men						 Women
Maybe
Definitely 			
Maybe
yes		
yes or yes
No		
yes		
n (%)
n (%)
n (%)
n (%)
Age, yr

Medical history
Drinking status
Smoking status
Physical activity
Sleep duration, h
BMIBreakfast
Education
Job status

Marital status
Ikigai
PsychologicalstressSense of hurry
Feeling of
being trusted

Definitely
yes or yes
n (%)

No
n (%)

40–49
143 (42.8)
50–59
291 (50.3)
60–69
225 (42.1)
70–79
109 (47.0)
Absence278 (45.6)
Existence
215 (48.3)
Never
130 (50.4)
Past
52 (37.7)
Current
579 (45.8)
Never
192 (47.8)
Past
181 (42.7)
Current
380 (46.4)
Exercise rarely
576 (46.8)
Exercise ≥ 1 h/week
145 (42.0)≥ 7 and < 9541 (46.7)<7
122 (40.9)≥990 (48.1)≥ 18.5 and < 25
567 (45.8)< 18.537 (50.7)≥ 25
116 (42.8)
Eat rarely
72 (46.2)
Eat
696 (45.7)
Age at graduation of < 18 years 491 (46.9)
Higher age at final graduation 216 (44.8)
Unemployed
112 (41.8)
Employed-worker or
340 (46.1)
self-employed worker
Farmer265 (46.2)
Single, divorced or widowed
45 (40.5)
Living with a spouse
585 (46.7)
Maybe yes or unknown
441 (50.5)
Definitely yes or yes
313 (40.8)
Maybe yes
531 (50.0)
Definitely yes or yes
152 (37.8)
No
67 (37.2)
Maybe yes
318 (45.1)
Definitely yes or yes
390 (46.9)
No
52 (43.0)

56 (16.8)
101 (17.5)
150 (28.0)
65 (28.0)
130 (21.3)
94 (21.1)
45 (17.4)
39 (28.3)
281 (22.2)
90 (22.4)
95 (22.4)
175 (21.4)
247 (20.0)
95 (27.5)
250 (21.6)
71 (23.8)
42 (22.5)283 (22.8)
11 (15.1)
58 (21.4)
32 (20.5)340 (22.3)
227 (21.7)
95 (19.7)
65 (24.3)

135 (40.4)**
186 (32.2)
160 (29.9)
58 (25.0)
202 (33.1)
136 (30.6)
83 (32.2)
47 (34.0)403 (32.0)
120 (29.8)
148 (34.9)
264 (32.2)
409 (33.2)*
105 (30.5)368 (31.7)
105 (35.3)
55 (29.4)
389 (31.4)
25 (34.2)
97 (35.8)
52 (33.3)
487 (32.0)
328 (31.4)
171 (35.5)
91 (33.9)*

166 (41.5)
299 (40.5)
297 (46.2)
146 (43.1)
388 (45.5)
168 (43.2)
603 (44.2)
16 (47.1)
180 (39.3)
738 (43.4)
16 (57.1)
17 (30.9)722 (43.0)
98 (40.3)
611 (44.6)
226 (39.2)
45 (39.1)
617 (42.6)
43 (40.6)
179 (44.1)
97 (41.8)811 (43.0)
532 (42.9)
305 (43.6)
382 (45.0)

45 (11.3)
108 (14.6)
98 (15.2)
72 (21.2)
130 (15.3)
43 (11.1)
210 (15.4)
1 (2.9)65 (14.2)
253 (14.9)
4 (14.3)
9 (16.4)
238 (14.2)
42 (17.3)
204 (14.9)
89 (15.5)
22 (19.1)
219 (15.1)
12 (11.3)
62 (15.3)
34 (14.7)
289 (15.3)
181 (14.6)
110 (15.7)
149 (17.6)

189 (47.2)**
331 (44.9)
248 (38.6)
121 (35.7)
334 (39.2)*
178 (45.7)
550 (40.4)
17 (50.0)
213 (46.5)
708 (41.7)
8 (28.6)
29 (52.7)
721 (42.8)
103 (42.4)
556 (40.5)
261 (45.3)
48 (41.8)614 (42.3)
51 (48.1)
165 (40.6)
101 (43.5)
788 (41.7)
527 (42.5)
285 (40.7)
317 (37.4)**

187 (25.3)

211 (28.6)

316 (41.8)

101 (13.4)

339 (44.8)

100 (17.5)
20 (18.0)
268 (21.4)
104 (11.9)
257 (33.5)
227 (21.4)
83 (20.6)
54 (30.0)156 (22.1)
195 (23.4)
17 (14.0)

208 (36.3)
46 (41.5)
401 (31.9)
329 (37.6)**
198 (25.7)
305 (28.6)**
167 (41.6)
59 (32.8)231 (32.8)*
247 (29.7)
52 (43.0)

101 (35.9)
110 (36.3)
593 (44.1)
632 (45.6)
249 (38.0)644 (46.5)
157 (35.3)
77 (35.3)
475 (48.4)
365 (39.0)
57 (33.3)

39 (13.9)
31 (10.2)215 (16.0)
138 (10.0)
174 (26.5)
220 (15.9)
38 (8.5)
56 (25.7)
124 (12.6)
169 (18.0)
26 (15.2)

141 (50.2)
162 (53.5)**
538 (39.9)
616 (44.4)**
233 (35.5)
521 (37.6)**250 (56.2)
85 (39.0)383 (39.0)**403 (43.0)
88 (51.5)

Maybe yes

533 (49.5)

225 (20.9)

319 (29.6)**613 (46.1)

216 (16.2)

502 (37.7)**

Definitely yes or yesNo

106 (36.6)
120 (41.0)

116 (40.0) 68 (23.4)
27 (9.2) 146 (49.8)

93 (35.6)
185 (38.4)

69 (26.5)
32 (6.6)

99 (37.9)
265 (55.0)

BMI, body mass index.
*P < 0.05.
**P < 0.001.

causes was not significant.
Previous studies1–9 reported that the presence ofikigai decreased mortality risk from all causes. But, thepresent study did not support the results of these studies, presumably because the adjusted confounders in thestudies1, 2, 4–9 were less than in our study. Sone et al.3
followed up 43,391 Japanese adults over 7 years, andDISCUSSION
In this study of Japanese men and women from 40 to
79 years, those who denied a feeling of being trusted
showed an increased mortality risk from all causes.
However, among both men and women who reported
having ikigai, psychological stress, sense of hurry or life
satisfaction, the relationship to mortality risk from all79

Y. Tokushima et al.
Table 6. Correlation coefficients between psychological factors by sex
Psychological stress
Men

Women

Sense of hurry

Feeling of being trusted

Ikigai–0.0030.167**
0.304**
Psychological stress		
0.211**
0.046
Sense of hurry			
0.163**
Feeling of being trusted				Ikigai–0.093**0.122**
0.226**
Psychological stress		
0.218**
0.044*
Sense of hurry			
0.169**
Feeling of being trusted				Life satisfaction
0.223**–0.084**0.063**
0.229**
0.152**–0.152**0.023
0.163*** P < 0.05.
** P < 0.001.
Table 7. Age-adjusted and multivariate HRs and 95% CIs for death according to psychological factors among men		Alive		n(%)
Do you have “ikigai” in your life?
1,239 (100.0)
Maybe yes or unknown
620 (50.0)
Definitely yes or yes
619 (50.0)
Do you feel stress during your daily life?
1,249 (100.0)
Maybe yes
794 (63.6)
Definitely yes or yes
327 (26.2)
No
128 (10.2)
Do you hurry to complete your daily work?
1,255 (100.0)
Maybe yes
515 (41.0)
Definitely yes or yes
660 (52.6)
No
80 (6.4)
Do you feel you are trusted by someone?
1,249 (100.0)
Maybe yes
830 (66.5)
Definitely yes or yes
225 (18.0)
No
194 (15.5)
Do you wish you could live your life over again? 1,240 (100.0)
Maybe yes
574 (46.3)
Definitely yes or yes
255 (20.6)
No
411 (33.1)

Dead
		
n (%)
439 (100.0)
276 (62.9)
163 (37.1)
432 (100.0)
297 (68.7)
81 (18.8)
54 (12.5)
442 (100.0)
209 (47.3)
190 (43.0)
43 (9.7)
448 (100.0)
271 (60.5)
69 (15.4)
108 (24.1)
439 (100.0)
194 (44.2)
117 (26.7)
128 (29.1)

Observed
HR [95% CI]
person-years Age-adjusted HR

Multivariate HR

2,996
1,855

1.00
1.00
0.64 [0.53–0.78]** 0.76 [0.56–1.04]

3,321
895
559

1.00
0.97 [0.76–1.24]
1.01 [0.76–1.34]

1.00
0.85 [0.57–1.26]
0.95 [0.59–1.53]

2,297
2,154
426

1.00
0.78 [0.65–0.94]*
1.20 [0.87–1.65]

1.00
0.80 [0.58–1.09]
0.73 [0.40–1.33]

3,034
763
1,133

1.00
1.00
0.81 [0.63–1.05]
0.76 [0.50–1.16]
1.59 [1.28–1.97]** 1.67 [1.13–2.45]*

2,154
1,320
1,352

1.00
1.10 [0.89–1.36]
1.04 [0.84–1.28]

1.00
1.10 [0.75–1.61]
0.97 [0.67–1.39]

		BMI, body mass index; CI, confidence interval; HR, hazard ratio.
† Multivariate HR was adjusted for age, medical history‡ (yes or no), education (age at graduation of < 18 years or higher age at final
graduation), job status (unemployed, employed or farmer), marital status (living with a spouse or other), drinking status (current
drinker, past drinker or non-drinker), smoking status (current smoker, past smoker or non-smoker), physical activity (exercise ≥ 1h/week or exercise rarely), sleep duration (< 7 h, ≥ 7 and < 9 h, ≥ 9 h), BMI (< 18.5, ≥ 18.5 and < 25, ≥ 25) and breakfast (eat or eat
rarely).
‡ Medical history: stroke, hypertension, myocardial infarction, kidney disease, liver disease, cholecystitis or cholelithiasis, diabetes
mellitus, gastric ulcer or duodenal ulcer, tuberculosis or pleurisy or cancer.
* P < 0.05.
** P < 0.001.

found that the mortality risk of all causes was significantly higher among subjects who had no ikigai after
adjustment of age, sex, marital status, education, job,
self-rated health, perceived mental stress, physical function, BMI, smoking, alcohol consumption, time spentwalking, sleep duration and medical history. The study
had a larger number of subjects, a larger number of decedents and more adjusted confounding factors than thepresent study. The reason for the different results may be

explained by the difference in classification of levels of
psychological factors and the reference group.
As for psychological stress, sense of hurry and life
satisfaction, the classification of levels of psychologicalfactors in a prior study1 was the same as in the present
study. But our study did not support their results except
age-adjusted sense of hurry among men and women.
The cause may be the difference of number of adjusted
confounding factors in the analysis.
80Psychological factors and mortality risk
Table 8. Age-adjusted and multivariate HRs and 95% CIs for death according to psychological factors among
women		
Alive		n(%)
Do you have “ikigai” in your life?
1,832 (100.0)
Maybe yes or unknown
1,243 (67.8)
Definitely yes or yes
589 (32.2)
Do you feel stress during your daily life?
1,841 (100.0)
Maybe yes
1,233 (67.0)
Definitely yes or yes
416 (22.6)
No
192 (10.4)
Do you hurry to complete your daily work?
1,883 (100.0)
Maybe yes
885 (47.0)
Definitely yes or yes
865 (45.9)
No
133 (7.1)
Do you feel you are trusted by someone?
1,851 (100.0)
Maybe yes
1,201 (64.9)
Definitely yes or yes
237 (12.8)
No
413 (22.3)
Do you wish you could live your life over again? 1,857 (100.0)
Maybe yes
801 (43.1)
Definitely yes or yes
275 (14.8)
No781 (42.1)

Dead
		
n (%)
268 (100.0)
187 (69.8)
81 (30.2)
265 (100.0)
190 (71.7)
38 (14.3)
37 (14.0)274 (100.0)
133 (48.5)
95 (34.7)
46 (16.8)
273 (100.0)
164 (60.1)
30 (11.0)
79 (28.9)264 (100.0)
107 (40.5)
48 (18.2)
109 (41.3)

Observed
HR [95% CI]
person-years Age-adjusted HR

Multivariate HR

2,097
912

1.00
0.99 [0.76–1.29]

1.00
1.10 [0.67–1.78]

2,155
420
398

1.00
0.90 [0.63–1.28]
0.98 [0.69–1.40]

1.00
0.84 [0.43–1.63]
1.04 [0.56–1.95]

1,467
1,086
520

1.00
0.82 [0.64–1.05]
1.46 [1.06–2.02]*

1.00
0.82 [0.50–1.33]
0.79 [0.38–1.61]

1,821
360
903

1.00
0.82 [0.56–1.20]
1.07 [0.78–1.46]

1.00
1.33 [0.67–2.62]
1.54 [0.93–2.53]

1,226
517
1,204

1.00
1.07 [0.78–1.46]
1.18 [0.92–1.50]

1.00
1.24 [0.61–2.54]
1.35 [0.83–2.20]

BMI, body mass index; CI, confidence interval; HR, hazard ratio.
† Multivariate HR was adjusted for age, medical history‡ (yes or no), education (age at graduation of < 18 years or higher age at final
graduation), job status (unemployed, employed or farmer), marital status (living with a spouse or other), drinking status (current
drinker, past drinker or non-drinker), smoking status (current smoker, past smoker or non-smoker), physical activity (exercise ≥ 1h/week or exercise rarely), sleep duration (< 7 h, ≥ 7 and < 9 h, ≥ 9 h), BMI (< 18.5, ≥ 18.5 and < 25, ≥ 25) and breakfast (eat or eat
rarely).
‡ Medical history: stroke, hypertension, myocardial infarction, kidney disease, liver disease, cholecystitis or cholelithiasis, diabetes
mellitus, gastric ulcer or duodenal ulcer, tuberculosis or pleurisy or cancer.
* P < 0.05.

aggravation of longevity prognoses.24–28 During the
6-year interval, having poor self-rated health and poorsocial roles were identified as significant predictors for
total mortality among both men and women.26 In addition, an 8-year follow-up study that surveyed 519 homebound elderly people aged 65 and over reported thatmale elderly individuals who did not leave their home
for travel, picnics or brief outings had a higher mortality
risk compared with those who did go out regularly. As
for women, because they often assume the roles of bothhousewife and mother, it is predicted that comparedwith males, continued opportunities for interactions
with others are beneficial until the individual becomes
senile.27 The feeling of being trusted, along with having
opportunities for interpersonal relationships and certain
roles, is considered an important factor in enjoying andsustaining a healthy end-of-life period. In addition, toprevent isolation or loneliness of individuals who retired,community’s support is considered necessary in maintaining interpersonal relations and having certain roles,
especially among men.

We found associations between feeling of being
trusted and mortality risk from all causes only amongmen. According to Tanno and Sakata,1 the mortality risk
from all causes for those who had no feeling of being
trusted increased 1.19 times for men and 1.17 times for
women compared with the risk for those who reported“maybe” to the feeling of being trusted. Sakata et al.4
showed that only among women, the mortality risk fromall causes in those who had no feeling of being trusted
increased compared with in those who had. We included
some adjustment factors such as life style habits and social factors to our analysis, and found more meaningful
results relevant to feeling of being trusted and mortality
risk.
The mechanism which underlies the preventive
effects of feeling of being trusted on mortality risk remains unclear. However, we have identified some possible explanations. There are domestic and international
reports on the effectiveness of talking and visiting withfriends and others through the participation in neighborhood and other social activities on preventing the81

Y. Tokushima et al.

There are several limitations to this study. First, thefeeling of being trusted was evaluated by a single question. Thus, because of the lack of contextual information
available to the respondents, we feel that the question
could be interpreted in both positive and negative ways.
Therefore, the reliability and validity of the questions
used in the present study should be more carefully evaluated. Second, because we assessed only one point in
time, changes in psychological status were not evaluated.
A previous study on the association between changes inikigai and mortality risk over a period of 6 years, however, showed that the loss of ikigai during the 6-year interval resulted in an increased risk of mortality.7 Therefore,such possible effects of changes in psychological statusover time need to be considered when evaluating ourpresent results. In addition, because psychological factors used in the present study were weak in correlation,
the factors should be further investigated with regard to
the effects of mortality risk, independently.
In conclusion, the present results suggest that the absence of feeling of being trusted increases the mortality
risk of all causes among middle-aged and elderly men
in rural areas. Our findings further suggest that interpersonal relationships comprise an important factor in having a long life.

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2001;56:535-40. Japanese with English abstract. PMID:
11519188
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Acknowledgments: We are grateful to Professor Yoneatsu Osaki,
Division of Environmental and Preventive Medicine, Department
of Social Medicine, School of Medicine, Tottori University Faculty of Medicine, and Professor Shin-ichi Yoshioka, Department of
Nursing Care Environment and Mental Health, School of Health
Science, Tottori University Faculty of Medicine, for their helpful
suggestions. We acknowledge the residents of Nichinan-town who
cooperated with the investigation.
The investigation of the baseline is based on the JACC study
supported by Grants-in-aid (11181101) for Scientific Research from
the Ministry of Education, Culture, Sports, Science and Technology of Japan.
The authors declare no conflict of interest.
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