Factors Associated with Worsening Post-Earthquake Psychiatric Symptoms in Patients Receiving Psychiatric Visiting Nurse Services During the 2024 Noto Peninsula Earthquake: A Retrospective Study

Abstract

On 1 January 2024, a magnitude 7.5 earthquake struck the Noto Peninsula in Ishikawa Prefecture, Japan, causing substantial damage to northern Noto. This study aimed to clarify the experiences of patients using a psychiatric visiting nurse service who were affected by the earthquake, and the influencing factors of worsening mental health symptoms after the earthquake. Participants were 114 patients using a psychiatric visiting nurse service in northern Noto. Data were collected retrospectively from nursing records. Factors associated with signs of worsening mental health symptoms were the continued use of home visiting nursing services after the disaster (n = 43, 46.7%; p = 0.040) and the intervention of a disaster psychiatric assistance team (DPAT) (n = 7, 77.8%; p = 0.034). No significant correlation was found between the number of relocations owing to evacuation and signs of worsening mental health symptoms. Although 61.4% of participants experienced more than one evacuation, the number of evacuations and relocations did not seem to directly affect the worsening of mental health symptoms. However, the results suggest a need for more direct interventions, such as the continued use of home visiting nursing services and the involvement of DPATs as an external resource, for patients exhibiting signs of worsening mental health symptoms.

1. Introduction

On 1 January 2024, a magnitude 7.5 earthquake struck the Noto Peninsula in Japan, triggering substantial ground deformation and a tsunami that caused widespread damage in northern Noto [1,2,3]. Seven months after the disaster, 191 evacuation shelters remained open, and 2086 people in Ishikawa Prefecture remained displaced [4]. Some evacuees are still receiving home care for chronic illnesses.

Previous research has consistently demonstrated that individuals living with pre-existing mental health conditions are disproportionately vulnerable during and in the aftermath of disasters [5]. This vulnerability is particularly marked during large-scale disasters. For example, during the 2011 Great East Japan Earthquake, individuals with pre-existing mental health conditions were identified as being one of the most at-risk populations, along with older people and those with disabilities [6]. These individuals often experience exacerbated mental health symptoms and reduced coping abilities in the aftermath of a disaster. Disasters have long-term psychosocial effects on all disaster victims, including those with pre-existing mental health conditions [7]. A study of individuals affected by Hurricane Katrina, which struck the southern United States in August 2005, reported that individuals with pre-existing mental illness were more likely to experience poor mental health outcomes post-disaster. Specifically, individuals with schizophrenia were 9.1 times more likely and those with affective disorders were 4.1 times more likely to experience negative mental health outcomes [8]. Furthermore, a literature review on evacuation and medication found that individuals with pre-existing mental health conditions who were affected by Hurricane Katrina reported difficulties accessing appropriate medication or reducing or discontinuing their medication [9].

Some research has also identified an increased risk of post-traumatic stress disorder (PTSD) and major depressive disorder among individuals affected by earthquakes [10]. Individuals with pre-existing mental illness living in affected areas are particularly vulnerable to experiencing severe mental health problems such as PTSD following a disaster [8]. Moreover, even individuals with pre-existing mental illness who do not directly experience the disaster but reside in areas distant from the disaster site may be at increased risk of experiencing extreme distress and developing mental illnesses compared with those without pre-existing mental health conditions [11]. A characteristic of mental illness is that the symptoms are not easily visible to others [12]. A recent study by Oe et al. found that approximately half of individuals with mental illness living in group homes indicated that they would not inform support staff of their condition if they were to evacuate to a public shelter in the event of a disaster [13]. In other words, individuals with mental illness living in the community may experience more severe effects from disasters compared with those without mental illness, but approximately half of them may not seek help by disclosing their condition when evacuating to public shelters. Considering these factors, it is essential to conduct research on the status of individuals with mental illness living in the community and receiving home care services, as well as to investigate the signs of worsening mental health symptoms post-disaster.

The aim of this study was to investigate the experiences and outcomes of individuals with mental illness who were receiving visiting nurse services during the 2024 Noto Peninsula earthquake (NPE). Specifically, the study explored the factors that contributed to the exacerbation of mental health symptoms following the disaster. This research has the potential to provide important evidence that could inform post-disaster interventions for individuals with pre-existing mental health conditions. By examining the experiences of people with mental illness residing in the community who have been affected by a disaster, the study findings could contribute to the development of more effective strategies for home visiting nursing services, as well as for support workers and policymakers in disaster shelters. Furthermore, this study uniquely focused on a peninsula, a geographic setting with distinct challenges, as demonstrated by the large-scale NPE. The Noto Peninsula is in an isolated position and has limited access to the mainland, making evacuation, the delivery of supplies, and personnel deployment very complex. By considering these geographical constraints, the present findings could provide valuable insights into the evacuation experiences and vulnerabilities of individuals with pre-existing mental health conditions in this type of location, thereby enhancing preparedness for future disasters. The findings from this study have the potential to inform disaster preparedness efforts not only in Japan but also in other regions worldwide with similar geographic characteristics.

2. Materials and Methods

2.1. Target Area and Epicenter of the NPE

The target area of this study was the Noto Peninsula, situated within Ishikawa Prefecture, Japan. Ishikawa Prefecture is located on the Sea of Japan side of central Honshu Island, with the Noto Peninsula extending northward into the Sea of Japan. Ishikawa Prefecture is a coastal region that encompasses an area of 4185 square kilometers; its coastline is approximately 580 km [14]. As of 1 April 2024, Ishikawa Prefecture had a population of 1,101,105 residents, of which 162,361 (14.7%) resided in the northern region of the Noto Peninsula, which comprises the municipalities of Nanao, Kashima District, Wajima, Suzu, and Hōsu District [15]. The Noto Peninsula is characterized by a predominantly low-relief landscape containing small mountains and rolling hills. Elevations in the region seldom exceed 300 m above sea level [14]. The exact epicenter of the NPE was in the city of Suzu, at the northernmost extremity of the Noto Peninsula.

2.2. Data Collection

The study participants were patients of a psychiatric visiting nurse service (PVNS) located in the northern part of the Noto Peninsula, Ishikawa Prefecture, Japan. This PVNS is in a region that was severely damaged in the NPE. The maximum seismic intensity in the northern part of the Noto Peninsula during the earthquake was 6 to 7 on the Japanese seismic intensity scale [16] (Figure 1). Data for this study were collected retrospectively from the PVNS medical records. To protect patient privacy, the name of the PVNS has been anonymized. The study period was from 1 January to 31 July 2024.

2.3. Survey Items

This retrospective, observational study examined nursing records from home visit nursing stations in the northern part of the Noto Peninsula, Ishikawa Prefecture. The survey comprised items on basic demographic information, signs of worsening mental health symptoms after the earthquake, and disaster-related data.

Basic demographic information comprised participants’ sex, age, and primary diagnosis. The authors converted the primary diagnosis recorded in the medical records into an International Statistical Classification of Diseases and Related Health Problems 11th version (ICD-11) code [17,18,19]. Disaster-related data comprised the presence or absence of cohabitants at the time of the disaster, the presence or absence of cohabitants after the disaster, whether or not the participant evacuated, the number of times they moved owing to evacuation, the use of health and welfare services before and after the disaster, whether or not their residence collapsed, whether or not they stopped using visiting nursing services after the disaster, intervention by the disaster psychiatric assistance team (DPAT), and signs of worsening mental health symptoms after the earthquake. Signs of worsening mental health symptoms after the earthquake were determined by visiting nurses during their interactions with users. The maximum seismic intensity at each participant’s residence was obtained from the Seismic Intensity Distribution Database published on the website of the Japan Meteorological Agency [16].

2.4. Data Analysis

Demographic characteristics of the participants, such as their age (mean and standard deviation [SD]) and the number of times they moved owing to evacuation (median and range), were calculated. Frequencies and percentages were calculated for categorical variables.

The relationship between signs of worsening mental health symptoms after the earthquake (1: No, 2: Yes) and basic demographic and disaster-related variables were analyzed. Age was categorized into two groups (1: <65 years, 2: ≥65 years), ICD-11 codes were categorized into two groups (1: Other than 6A20 [schizophrenia] and 2: 6A20 and 1: Other than 6A80 [symptomatic and course presentations for mood episodes in mood disorders] and 2: 6A80), and whether or not the participant had to move owing to evacuation was categorized into two groups (1: No, 2: Yes). Chi-square tests or Fisher’s exact tests were used to examine the association between each variable. The Cochran–Armitage test was used to examine the trend of an association between the number of times moved owing to evacuation and signs of worsening mental health symptoms. All data analyses were performed using SPSS Ver29 (IBM Corporation, Armonk, NY, USA).

The geographical distribution of participants’ residences was analyzed using a geographic information system (GIS). Polygon data on administrative divisions in Ishikawa Prefecture and point data on prefectures were obtained from the Ministry of Land, Infrastructure, Transport and Tourism website and mapped [20,21]. GIS analysis was performed using ArcGIS Pro 3.2.1 (ESRI, Redlands, CA, USA).

2.5. Ethical Considerations

This study was conducted in strict adherence to ethical guidelines and received approval from the University Medical Research Ethics Review Committees at the respective institutions of the authors (No. C093, Nursing Research Ethics Review Committee No. 24-3). Prior to data collection, informed consent was obtained from all participants using an opt-out approach. To ensure that participants fully understood the study, staff members who specialized in the care of PVNS patients provided detailed explanations of the study objectives, research methods, and voluntary nature of participation. Participants were provided with an informed consent document that described the study purpose, methods, and assurance of anonymity in the dissemination of the findings.

The study was conducted in accordance with ethical guidelines. Participants were provided with informed consent documents detailing the study objectives, methods, and privacy protection measures; visiting nurses explained the contents of the documents to patients. Because of the difficulty of obtaining direct consent from participants, an opt-out approach was used. Participants could decline to participate in the study by contacting the visiting nurse or by using the contact details provided on the form within 14 days of receiving the information. Patient privacy was strictly protected, including that of patients who declined to participate, and all collected data were anonymized. This study was approved by the institutional review boards of the authors’ universities (approval no. C093, 24-3).

3. Results

3.1. Characteristics of Patients Using PVNS

There were 114 study participants. The mean (SD) age was 42.7 (16.9) years. The age groups that contained the most participants were 50–59 years (n = 25, 21.9%), followed by 30–39 years and 40–49 years (both n = 21, 18.4%). Most participants were female (n = 63, 55.3%). The most common primary diagnoses (ICD-11 codes) documented in the participants’ medical records were 6A20 (n = 52, 45.6%), 6A80 (n = 25, 21.9%), and 6A02 (n = 12, 10.5%). Participant characteristics are shown in

Table 1. Characteristics of PVNS patients (n = 114).

Item	Category	n	%
Age (years), mean (SD)	42.7 (16.9)
Age group
	10 s	4	3.5
	20 s	4	3.5
	30 s	21	18.4
	40 s	21	18.4
	50 s	25	21.9
	60 s	16	14.0
	70 s	18	15.8
	80 s	5	4.4
Sex
	Male	51	44.7
	Female	63	55.3
ICD-11 code 1
	6A00	5	4.4
	6A02	12	10.5
	6A05	3	2.6
	6A20	52	45.6
	6A60	3	2.6
	6A80	25	21.9
	6B01	1	0.9
	6B43	2	1.8
	6B60	1	0.9
	6C40	5	4.4
	6E8Y	2	1.8
	7A00	1	0.9
	8A22	1	0.9
	Other	1	0.9

¹ The primary diagnoses in the nursing records were recorded using ICD-11 codes. ICD-11: International Statistical Classification of Diseases and Related Health Problems 11th version; SD: standard deviation; PVNS: psychiatric visiting nurse service.

.

3.2. Residence of PVNS Patients

There was a high proportion of PVNS patients among the residents of Wajima (n = 55, 48.2%), Noto (n = 28, 24.6%), and Suzu (n = 20, 17.5%). The northern part of Noto in particular was subjected to intense seismic activity during the earthquake, with reported seismic intensities between 6 and 7. The spatial correlation between the distribution of PVNS cases and the severity of the ground shaking are shown in Figure 1, which is a map of the seismic intensity and the locations of the participating prefectures.

3.3. Factors Related to the Disaster Situation and Signs of Worsening Mental Health Symptoms in PVNS Patients

The study sample consisted of 114 individuals, with a slight majority (59; 51.8%) residing in areas that experienced a maximum seismic intensity of 6+. The remaining participants (55; 48.2%) were exposed to more severe shaking, as they lived in regions that had a maximum intensity of 7. The earthquake triggered extensive displacement among the study population; a substantial proportion (88; 77.2%) had to evacuate their homes. The frequency of relocations varied considerably, with a median of two displacements. Although 26 participants (22.8%) did not relocate, others experienced multiple displacements, including 38 individuals (33.3%) who relocated twice and 18 (15.8%) who relocated three or more times. The effect of the earthquake on mental health was evident, as 48 participants (42.1%) reported a worsening of their mental health symptoms post-disaster, whereas the remaining 66 (57.9%) did not.

Table 2. Factors associated with worsening mental health symptoms in PVNS patients post-earthquake (n = 114).

				Signs of Worsening Mental Health Symptoms
Variable	Category	Total		No		Yes
		n	%	n	%	n	%	p Value
Age (years), mean (SD)	42.7 (16.9)							0.431
Age group	<65 years	85	74.6	44	51.8	41	48.2	0.029
	≥65 years	29	25.4	22	75.9	7	24.1
Sex	Male	51	44.7	33	64.7	18	35.3	0.185
	Female	63	55.3	33	52.4	30	47.6
6A20 code	Other than 6A20	62	54.4	36	58.1	26	41.9	0.968
	6A20	52	45.6	30	57.7	22	42.3
6A80 code	Other than 6A80	111	97.4	64	57.7	47	42.3	1.000
	6A80	3	2.6	2	66.7	1	33.3
Number of relocations for evacuation, median (range)	2.0 (0–5)							0.881
Relocations for evacuation	No	26	22.8	17	65.4	9	34.6	0.379
	Yes	88	77.2	49	55.7	39	44.3
Maximum seismic intensity in prefecture of residence	6+	59	51.8	36	61.0	23	39.0	0.484
	7	55	48.2	30	54.5	25	45.5
Presence or absence of cohabitants during the disaster	No	39	34.2	24	61.5	15	38.5	0.570
	Yes	75	65.8	42	56.0	33	44.0
Evacuated	No	26	22.8	17	65.4	9	34.6	0.379
	Yes	88	77.2	49	55.7	39	44.3
Presence or absence of cohabitants post-disaster	No	78	68.4	44	56.4	34	43.6	0.637
	Yes	36	31.6	22	61.1	14	38.9
Use of health and welfare services pre-disaster	No	50	43.9	27	54.0	23	46.0	0.457
	Yes	64	56.1	39	60.9	25	39.1
Use of health and welfare services post-disaster	No	71	62.3	40	56.3	31	43.7	0.665
	Yes	43	37.7	26	60.5	17	39.5
Collapse of residence	No	99	86.8	59	59.6	40	40.4	0.345
	Yes	15	13.2	7	46.7	8	53.3
Stopped using visiting nursing services after the disaster	No	92	80.7	49	53.3	43	46.7	0.040
	Yes	22	19.3	17	77.3	5	22.7
DPAT intervention	No	105	92.1	64	61.0	41	39.0	0.034 1
	Yes	9	7.9	2	22.2	7	77.8

χ² test, except for ¹ Fisher’s exact test. DPAT: disaster psychiatric assistance team, SD: standard deviation.

and

Table 3. Association between number of relocations and worsening mental health symptoms (n = 114).

				Signs of Worsening Mental Health Symptoms
Variable	Category	Total		No		Yes
		n	%	n	%	n	%	p Value
Number of relocations for evacuation	0	26	22.8	17	65.4	9	34.6	0.881
	1	18	15.8	9	50.0	9	50.0
	2	38	33.3	22	57.9	16	42.1
	3	18	15.8	9	50.0	9	50.0
	4	11	9.6	7	63.6	4	36.4
	5	3	2.6	2	66.7	1	33.3
Total		114		66	57.9	48	42.1

Cochran–Armitage test.

present the results of univariate analyses conducted to explore the relationship between worsening mental health symptoms and a range of basic attributes and disaster-related experiences. Notably, continued use of home visiting nursing services post-disaster (n = 43, 46.7%; p = 0.040) and involvement with a DPAT (n = 7, 77.8%; p = 0.034) were found to be significantly associated with worsening mental health symptoms. These findings suggest that individuals who continued to receive home care or engaged with specialist mental health support services may have experienced greater psychological distress in the aftermath of the disaster. However, the number of relocations experienced was not significantly correlated with the worsening of mental health symptoms, as indicated by the results of the Cochran–Armitage test (Table 3).

4. Discussion

This investigation explored the post-disaster experiences of 114 PVNS patients who were directly affected by the large-scale NPE of 2024. The primary objective was to ascertain the factors associated with the exacerbation of mental health symptoms among this vulnerable patient population in the aftermath of the earthquake. The study findings indicate a statistically significant correlation between the persistence of worsening mental health symptoms and both the continued use of home nursing services and the provision of interventions by the DPAT. Conversely, the frequency of relocations for evacuation purposes did not show a significant association with deterioration in mental health outcomes.

Because of its position and mountainous terrain, the Noto Peninsula is particularly vulnerable to infrastructure damage. The earthquake caused widespread road disruption, severely hindering relief efforts and delaying the delivery of essential supplies [22]. The severe landslides and damage to transportation infrastructure further exacerbated the situation, making it extremely difficult for external assistance to reach the affected areas [23]. As a consequence, the post-earthquake recovery process has been very slow. To accommodate the displaced population, public facilities were initially used to house evacuees. However, as the disaster response progressed, many evacuees were forced to relocate to secondary shelters designed for longer-term stays. In Ishikawa Prefecture, a unique shelter system incorporating accommodation was established, facilitating multiple relocations for a large number of evacuees [24]. This repeated displacement has undoubtedly added to the psychological stress experienced by individuals affected by the earthquake. It is possible that some patients may have discontinued home visiting nursing services because they had to evacuate to distant locations away from the disaster area. However, dedicated home visiting care nurses may have persevered in providing essential services to patients with signs of worsening mental health, despite the chaotic post-disaster environment. The correlation between receiving ongoing home nursing services and worsening mental health symptoms is difficult to interpret. It is unclear whether the observed exacerbation was a consequence of the services, or whether the services were directed preferentially towards individuals with pre-existing severe mental health conditions who were more susceptible to symptom deterioration. Additionally, for patients with more complex mental health conditions that necessitate specialized medical care, support workers stationed at evacuation shelters may have sought the assistance of a DPAT to provide the necessary interventions. It is unclear whether the patients who engaged with DPAT services were predisposed to a decline in mental health because of pre-existing severe conditions, or whether their conditions deteriorated after the earthquake, necessitating DPAT intervention. During the NPE, DPATs were dispatched from 9 January 2024, and by 30 January, 116 teams had been deployed to the affected areas [25,26]. DPATs play a role in supporting the mental health care system and psychiatric institutions in disaster-stricken areas [27]. The DPAT organization was established in the aftermath of the Great East Japan Earthquake to coordinate disaster response efforts related to mental health and the mental health system in affected regions [28]. During their activities in the NPE, DPATs may have intervened with PVNS patients who were in evacuation shelters. Previous studies conducted in Japan have suggested that DPATs play an essential role in managing acute distress and addressing severe mental health conditions among individuals with pre-existing psychiatric disorders [29,30]. Given these findings, it is plausible that DPATs provided similar support to patients and their families during the NPE. Some of the patients using the PVNS were living in group homes. A previous study we conducted found that individuals with mental illness living in group homes are willing to seek assistance from the local government during evacuations [31]. Considering this, it is possible that individuals with mental illness may have proactively sought help and requested support from DPATs. However, our study does not provide detailed information about how the continued use of home nursing services was determined, how it affected signs of worsening mental health symptoms, or the specific pathways of DPAT intervention and its effect on patients’ mental health and evacuation experiences. Therefore, further detailed research is necessary.

Disasters and the subsequent displacement have been shown to adversely affect people’s mental health [32,33,34]. Individuals with pre-existing mental health conditions are particularly vulnerable to environmental changes and may experience considerable exacerbation of their symptoms following a disaster [33]. Specifically, disruptions to familiar routines and support networks can lead to increased psychological distress and worsening mental health symptoms [5,35]. Acute psychological distress following disasters often includes negative emotions and cognitive dysfunction and distortion (e.g., reduced concentration, confusion, unwanted thoughts or memories), as well as interpersonal difficulties and physical symptoms [36]. A study of people forced to relocate because of flooding in England showed that people who evacuated had a higher risk of depression, anxiety, and PTSD compared with those who did not evacuate [37]. This suggests that pre-existing mental health vulnerabilities and the broader environmental impact of the disaster may have contributed more to the deterioration of mental health than the physical act of relocation. Considering the well-documented role of community resilience in mitigating the effects of disasters [38,39], strong community resilience and effective support mechanisms may have attenuated the negative mental health consequences of displacement. However, given the complexities of human experience and the many factors that can affect mental health, such as family and social support, and socioeconomic conditions, it is difficult to draw definitive causal conclusions. Additionally, the support provided by PVNS nurses, other support workers, and community members may have played a role in the responses of patients. In contrast, the present findings suggest that the number of relocations owing to evacuation may not significantly affect the worsening of patients’ mental health. Furthermore, the participants of the present study were individuals whose mental health conditions were stable enough to allow them to live in the community while using the PVNS, which may have affected the results. However, as this study did not investigate the support received by PVNS users at evacuation sites, these speculations remain unconfirmed. Therefore, based on the available evidence, it is premature to definitively conclude that there is no correlation between the exacerbation of mental health symptoms during a disaster and factors such as environmental changes or the frequency of relocation. Further in-depth investigations are warranted to elucidate the complex interplay between these variables and their effects on individuals’ mental well-being in the aftermath of disasters.

5. Limitations of the Study

This study had several limitations that may have affected the generalizability and robustness of the findings. First, the data were exclusively sourced from a single home visiting nursing station, potentially limiting the representativeness of the results and failing to take into account possible variations across different regions and health care facilities. As a result, generalizing the findings to other contexts may be challenging. Second, the temporal scope of the study was restricted by the reliance on retrospective data collected from previous home care records. This limitation hindered the acquisition of comprehensive patient information, such as socioeconomic background and detailed circumstances surrounding the earthquake, pre-existing mental health conditions, and the nature of the interventions, which may have introduced bias into the study results. This study showed that the worsening of mental health symptoms was significantly correlated with the continuation of home care services and the involvement of DPATs. However, because of the small sample sizes in the subgroup analyses, the study’s statistical power and the reliability of the results were low, warranting caution in interpretation. Additionally, this study did not investigate whether mental health symptoms worsened before or after the provision of services, or the status of such symptoms before and after the involvement of the DPAT. The lack of standardized measures of the effectiveness of DPAT intervention and ongoing nursing services meant that we could not assess their direct influence on mental health outcomes. The use of longitudinal designs in future studies would help to capture temporal relationships between these variables. Additionally, at the beginning of this study, only the condition of using home care services was investigated, and the severity of patients’ mental health symptoms at the beginning of the study was not examined. It is important to note that although the retrospective and cross-sectional study design facilitates the exploration of associations between factors at a specific point in time, it does not permit the determination of temporal precedence or the inference of causal relationships between variables, making it unclear whether symptom deterioration preceded or followed interventions. Furthermore, the signs of worsening mental health symptoms after the disaster were based on subjective observations by nurses, and the timing of these observations was not consistent. However, although the data were subjective, they provide a useful, broad perspective on the issue and could provide an important basis for more objective future assessments. To address these limitations and obtain more robust findings, it is necessary to incorporate standardized tools and measures for assessing mental health outcomes, as well as conduct large-scale collaborative studies involving multiple home care agencies. Such a study would enable a more comprehensive analysis of the factors associated with worsening mental health symptoms among PVNS patients in the context of natural disasters.

6. Conclusions

This study aimed to elucidate the factors contributing to the exacerbation of mental health symptoms among individuals using a PVNS who were residing in the severely affected northern Noto region during the devastating NPE of 2024. The findings of this research may provide important insights for the development of targeted support measures designed to address the unique needs of PVNS patients during disaster events. A substantial proportion of the study participants (42.1%) exhibited signs of worsening mental health conditions. Moreover, many participants (77.1%) experienced evacuation, with 61.4% undergoing multiple relocations. However, the frequency of relocations owing to disaster-related evacuations did not appear to be a direct predictor of deteriorating mental health outcomes. Conversely, the results suggest an urgent need for more direct and intensive interventions, such as the provision of ongoing home nursing services and the involvement of DPATs as an external resource, for patients showing signs of deteriorating mental health.