AN EARTHQUAKE MEASURING an upper 6 on the 7-point Japanese intensity scale (6.7 on the Richer scale) hit northern Nagano and Niigata on 12 March, the day after the 2011 Great East Japan Earthquake. Tsunan, located close to the epicenter, is an intermediate and mountainous town in Niigata with a population of 11 035. According to 2010 census figures, 35% of the population is aged 65 or over. Immediately after the earthquake, 740 people were forced to take shelter. Fortunately no one was killed by the earthquake; however, assuming weak community resilience to the disaster in this depopulated area, the earthquake may have had a significant psychological impact on the sufferers.1
We surveyed 3078 sufferers in Tsunan (Niigata), an intermediate and mountainous area of Japan, after the 2011 Northern Nagano Prefecture Earthquake. More subjects reported fear of the earthquake or related anxiety symptoms and insomnia in Tsunan than in the control group. Female sex and older age were found to be risk factors for poor psychological outcome. Those with risk factors should be carefully followed up.
From 24 March to 15 April, mental health professionals visited 1251 households (4406 population) in the devastated districts of Tsunan, and 934 households, with a population of 3078 (mean age [SD], 54.1 [25.2]), gave information about their families (Table 1). Because of absence, only 35.7% (mean age [SD], 68.3 [17.2]) was interviewed directly. The ratios of women and the elderly (≥65 years) in the interviewees were higher than in those not interviewed (P ≤ 0.05). This survey was approved by the Ethics Committee of Niigata University School of Medicine.
|Refuge to shelter||Yes||194||6.3|
|Refuge to vehicle||Yes||496||16.1|
Using a survey sheet, interviewers scored Likert-type responses for health condition, subjective psychological symptoms (e.g. fear of the earthquake, jitters, irritability) and somatic symptoms (e.g. back pain, headache, stiffness of neck), insomnia and drinking. Individual responses in Tsunan were compared to those in Yoshitani (Ojiya, Niigata) as a control with similar demographics to Tsunan. In Yoshitani, the mean age (SD]) of 1305 subjects (male, 635; female, 670) was 49.5 (24.9) years and 30.4% of them were aged 65 or over.
The independence of two factors was tested with two-tailed χ2-test (spss statistics 19, Chicago, IL, USA). P-values < 0.05 indicated statistical significance.
Table 2 shows that overall effects of the relevant earthquake on the health of the subjects were relatively limited. However, more subjects reported any subjective symptoms and insomnia in Tsunan than in the control group, while a reversed relation was found on drinking. Among the subjective symptoms, fear of the earthquake or related anxiety symptoms were more frequent in Tsunan than in the control group (42.7% vs 8.5%, P ≤ 0.05), while somatic symptoms were more frequent in the control than in Tsunan subjects (71.0% vs 26.1%, P ≤ 0.05).
|Item||Category||Total subjects||%||Interviewed||%||Control||%||χ2 statistic (d.f.)||P-value|
|Health condition||Good||2265||73.6||722||65.8||999||76.6||3.4 (2)||0.18|
|Neither good nor bad||311||10.1||182||16.6||160||12.3|
|Subjective symptoms||Yes||552||17.9||393||35.8||182||13.9||14.4 (1)||<0.01|
|Drinking||None or sometimes||1560||50.7||750||68.3||669||51.3||14.3 (1)||<0.01|
In Tsunan interviewees, more women (odds ratio [OR] = 2.11/1.87) and those aged 65 or over (OR = 2.12/1.56) had any subjective symptoms/insomnia than men and those aged younger than 65, respectively (all P < 0.01). These results are consistent with those from the total subjects.
The survey revealed an increase in anxiety and insomnia after the earthquake in Tsunan sufferers. Women and older age were found to be risk factors for poor psychological outcome.
There are few published reports on the early effects of wide-scale earthquake disasters in rural areas of Japan.1 Regarding the earthquakes in East Asia, Kato interviewed the evacuees of the 1995 Hanshin–Awaji earthquake, and found they experienced sleep disturbances, hypersensitivity, irritability and depression.2 Chen reported insomnia, palpitations, nervousness and dizziness as the most common psychiatric symptoms among the survivors from the 1999 earthquake in Taiwan.3 Wang estimated the rate of post-traumatic stress disorder at 62.8% among the survivors of the 2008 Sichuan earthquake.4 The increased anxiety found in our survey was consistent with these studies, although the severity appeared milder.
The studies in Taiwan and China and the present study concurrently pointed out female sex as a risk factor for poor psychological outcome; however, age was not determined in the former two studies. Besides methodological issues, the difference in subject age appears important. Mean ages in the Taiwan and China studies were 50 and 38 years, respectively, 54 years in our subjects and 68 years in the interviewees. The elderly may be more vulnerable to disaster stress than younger survivors.
Despite the limitation that not all sufferers were interviewed, our survey suggests the earthquake has certainly increased anxiety and insomnia among sufferers in Tsunan. Those with risk factors should be carefully followed up.
The authors are grateful to Yoko Oguchi at Tsunan town office. This study was supported by a Grant for Promotion of Niigata University Research Projects (No.156208–521212).