2025 Volume 47 Issue 1 Pages 5-14
With the increasing incidence of dementia in Japan due to an aging population and declining birthrate, supporting family caregivers is crucial. A survey was conducted at the hospital of the University of Occupational and Environmental Health, Japan from October 1, 2021, to February 29, 2024, involving dementia patients and their working caregiver relatives. The survey assessed health, living, work, caregiving status, sociodemographic factors, and the care recipient’s condition. A total of 214 patient-caregiver pairs participated; consent was obtained from 212 pairs, and data were collected from 166 caregivers. The caregivers were predominantly women, with 54 (33%) male caregivers and a mean age of 54.7 years. Health status was reported as good (33%) or fair (50%); however, 46% experienced sleep disturbances, 44% had psychological distress, 18% reported work dysfunction, and 8% noted poor social adjustment. Most of the care recipients were women (65%), with a mean age of 79.8 years. The most common diagnoses were mild cognitive impairment (37%) and Alzheimer’s disease (35%), with an average mini-mental state examination score of 21.6. This study outlines the survey protocol, focusing on the health, work, and caregiving conditions of working relatives caring for dementia patients.
The population of Japan is aging, and, given the declining birthrate, it is estimated that the number of people aged 65 years and older will reach one in three by 2038 [1]. According to a 2012 survey, there are 4.62 million elderly people with dementia, and this number is expected to reach 8.5 million by 2060 [2]. The total social cost of dementia is 14.5 trillion yen, with informal care cost estimated at 6.2 trillion yen. The average informal care time per person requiring dementia care that is provided free of charge by relatives and others is 24.97 hours/week, and the annual informal care cost amounts to 3,821,000 yen/year [3].
Among caregivers, 57.5% are working and younger than those who are not working [4]. The number of women and workers aged > 65 years has increased in recent years [5]. Traditionally, the role of caregiver was assumed by family members who did not work. As the number of family members per household decreased, an increasing number of working people became caregivers. The burden on workers during caregiving is not only financial; it also causes psychological distress, such as anxiety and depression [6, 7]. Preventing health problems, caregiver turnover, balancing caregiving and work, and dementia caregiving are a public health challenge, as the proportion of the working-age population is rapidly declining.
Previous studies have examined the association between caregivers’ mental health condition and caring for elderly relatives among Japanese workers [8, 9], but no studies have so far examined the association between working caregivers’ health and work function and their living and working environment, nor the condition of the care recipient. This study describes the protocol and provides an overview of a survey of patients with dementia and their relatives who work while caring for them, focusing on their health, life, work, and the condition of the care recipient.
Subject recruitment procedure
The survey is named the Sustaining for Aging dementia relatives Support And Employment (SASAE) project, and was designed as a prospective cohort study. The subjects were caregivers and care recipients. The recruitment setting was the outpatient clinic for dementia at the hospital of the University of Occupational and Environmental Health, Japan, that had been visited by patients and their relatives. The recruitment period ranged from October 2021 to February 2024, during which period informed consent was obtained from patients diagnosed with dementia or mild cognitive impairment and their relatives (214 pairs), with 212 pairs agreeing to participate in the study. The baseline survey was conducted using medical records and questionnaires. One year after the baseline survey, each participant was followed up with a subsequent questionnaire. This survey was approved by the Ethics Committee of the University of Occupational and Environmental Health, Japan, and written consent was obtained from the subjects (R3–010).
Measurements
A baseline survey was conducted for caregivers using a questionnaire. The survey items included age; sex; academic background; marital status; family structure; relationship with the care recipient; cohabiting status; lifestyle habits such as smoking, drinking, and exercise; lifestyle changes; and health condition, caregiving status, employment status, and support status. Sleep status was assessed using the Athens Insomnia Scale (AIS), psychological distress was measured using the Kessler 6 (K6), work function was evaluated with the Work Functioning Impairment Scale (WFun), and social function was assessed using the Social Adaptation Self-evaluation Scale (SASS). Questionnaires were completed by caregivers and collected via mail. Information on care recipients, including age, sex, diagnosis, duration of illness, long-term care insurance levels, care support status, Mini-Mental State Examination (MMSE), Clock Drawing Test (CDT), Neuropsychiatric Inventory Questionnaire (NPI-Q), Physical Self-Maintenance Scale (PSMS), and Instrumental Activities of Daily Living (IADL) were obtained from their medical records. In the follow-up survey, questionnaires were sent to caregivers to assess their care, health, and living and working conditions, including K6 and WFun, and were returned by mail (Table 1).
| Survey | ||
|---|---|---|
| baseline | follow-up | |
| Caregiver | ||
| age | ○ | |
| sex | ○ | |
| academic background | ○ | |
| marital status | ○ | ○ |
| family structure | ○ | |
| relationship with the care recipient | ○ | |
| cohabiting status | ○ | |
| lifestyle habits | ○ | |
| lifestyle changes | ○ | ○ |
| health condition | ○ | ○ |
| caregiving status | ○ | ○ |
| employment status | ○ | ○ |
| support status | ○ | |
| AIS | ○ | |
| K6 | ○ | ○ |
| WFun | ○ | ○ |
| SASS | ○ | |
| Care recipients | ||
| age | ○ | |
| sex | ○ | |
| diagnosis | ○ | |
| duration of illness | ○ | |
| long-term care insurance levels | ○ | |
| care support status | ○ | ○ |
| MMSE | ○ | |
| CDT | ○ | |
| NPI-Q | ○ | |
| PSMS | ○ | |
| IADL | ○ | |
AIS: Athens Insomnia Scale, K6: Kessler 6, WFun: Work Functioning Impairment Scale, SASS: Social Adaptation Self-evaluation Scale, MMSE: Mini-Mental State Examination, CDT: Clock Drawing Test, NPI-Q: Neuropsychiatric Inventory Questionnaire, PSMS: Physical Self- Maintenance Scale, IADL: Instrumental Activities of Daily Living
The AIS is a self-assessment rating scale that estimates nocturnal sleep disturbances and daytime dysfunctions based on the International Statistical Classification of Diseases and Related Health Problems 10th Revision (ICD-10) diagnostic criteria for insomnia. The cutoff for identifying pathological insomnia in the Japanese version is 6 points [10]. The K6 is a rating scale designed to screen for psychological distress and has been validated in the Japanese version [11, 12]. In this survey, a score of 5 or higher on the K6 was considered the cutoff value for mild psychological distress and a score of 13 or higher was considered the cutoff value for severe psychological distress. The WFun is a questionnaire that measures the degree of work dysfunction caused by health problems; a score of 21 or above indicates suspected work dysfunction [13]. The SASS assesses social function in depressed patients and has been validated in the Japanese version; a score of 25 or below on the SASS indicates poor social functioning [14].
The MMSE tests cognitive function to assess orientation, memory, attention, calculation, language, and visuospatial cognition, and is useful for screening cognitive impairment and estimating the severity of cognitive impairment. The full score is 30, with a score of 23 or less indicating suspicion of dementia [15]. The CDT is a simple and effective cognitive test used primarily to assess visuospatial and executive functions [16]. The NPI-Q is a caregiver-administered tool to evaluate the behavioral and psychological symptoms of dementia (BPSD) in patients. It measures the severity of symptoms, such as delusions, hallucinations, agitation, depression, and anxiety, as well as the distress they cause to caregivers [17, 18]. The PSMS is used to assess the basic activities of daily living (ADLs) in elderly individuals, such as toileting, feeding, dressing, grooming, and mobility [19, 20]. The IADL scale assesses more complex daily tasks required for independent living, such as managing finances, transportation, shopping, meal preparation, housework, and medication management. It is often used to evaluate the functional status of older adults [19, 20]. The perfect scores are 5 for men and 8 for women.
Statistical analysis
Descriptive statistics are presented on the participants’ characteristics.
In the baseline survey, questionnaires were collected from 166 caregivers (78%) and information on 212 care recipients was collected from medical records. Caregivers included 54 men and 112 women, with an average age of 54.7 years. Among the caregivers, 74% were married, with an average of 2.9 people living with them. More men (52%) had graduated from university or graduate school, whereas more women (45%) had graduated from a vocational school, junior college, or college of technology. Regarding employment type, 50% of the caregivers were employed as full-time employee, with a higher proportion observed among the men (67%) compared to the women (42%). More than half of the men were engaged in desk work, while about one-third each of the women were engaged in desk work, interpersonal work, or labor. Ninety-two percent of the caregivers were engaged in daytime-only shifts, while rotating shifts were more frequently observed among the women (8%) than the men (4%). Smoking, drinking, and exercise were more frequent among the men than the women. They slept an average of 6.3 hours and woke up 0.3 times during the night to provide care. Health conditions were not extremely poor, with most being good (33%) or fair (50%). Forty-six percent of the caregivers had an AIS score of 6 or higher, indicating the presence of sleep disorders. Caregivers with K6 scores of 5 or higher and 13 or higher were 44% and 7%, respectively. Caregivers whose work function was adversely affected accounted for 18%, and those with poor social adaptation accounted for 8% (Table 2).
| Characterictic | Caregiver | ||
|---|---|---|---|
|
Total (N=166) |
Men (n=54) |
Women (n=112) |
|
| age, y, mean | 54.7 (9.3) | 57.9 (9.3) | 53.1 (8.9) |
| sex, man (%) | 54 (33%) | 54 (100%) | – |
| currently married (%) | 122 (74%) | 46 (87%) | 76 (69%) |
| number of cohabiting families, mean | 2.9 (1.3) | 2.8 (1.2) | 2.9 (1.4) |
| academic background (%) | |||
| junior high school | 2 (1%) | 0 (0%) | 2 (2%) |
| high school | 51 (31%) | 16 (30%) | 35 (32%) |
| vocational school/junior college/college of technology | 60 (36%) | 10 (19%) | 50 (45%) |
| university/graduate school | 52 (32%) | 28 (52%) | 24 (22%) |
| employment status (%) | |||
| full-time employee | 81 (50%) | 35 (67%) | 46 (42%) |
| contract/ commissioned employee | 18 (11%) | 6 (12%) | 12 (11%) |
| part-time/ temporary worker | 37 (23%) | 3 (6%) | 34 (31%) |
| dispatched worker | 1 (1%) | 0 (0%) | 1 (1%) |
| self-employed | 25 (15%) | 8 (15%) | 17 (15%) |
| job type (%) | |||
| Mainly desk work (clerical or computer work) | 69 (43%) | 28 (55%) | 41 (38%) |
| Mainly talking to people (customer service, sales, selling, etc.) | 40 (25%) | 7 (14%) | 33 (30%) |
| Mainly labor (work at production sites, physical work, nursing care, etc.) | 51 (32%) | 16 (31%) | 35 (32%) |
| shift work status (%) | |||
| daytime shifts only | 149 (92%) | 50 (96%) | 99 (90%) |
| night shifts only | 2 (1%) | 0 (0%) | 2 (2%) |
| shift work | 11 (7%) | 2 (4%) | 9 (8%) |
| current smoker (%) | 25 (15%) | 16 (30%) | 9 (8%) |
| drinking almost daily (%) | 39 (24%) | 26 (48%) | 13 (12%) |
| exercise almost daily (%) | 27 (16%) | 12 (23%) | 15 (13%) |
| hours of sleep, mean | 6.3 (1.1) | 6.4 (1.3) | 6.2 (1.1) |
| number of times to get up at night for care, times, mean | 0.3 (1.0) | 0.3 (0.7) | 0.3 (1.1) |
| health condition (%) | |||
| good | 51 (33%) | 18 (35%) | 33 (31%) |
| fair | 78 (50%) | 25 (49%) | 53 (50%) |
| not so good | 25 (16%) | 8 (16%) | 17 (16%) |
| poor | 3 (2%) | 0 (0%) | 3 (3%) |
| AIS ≥ 6 (%) | 70 (46%) | 24 (47%) | 46 (45%) |
| K6 ≥ 5 (%) | 72 (44%) | 21 (40%) | 51 (46%) |
| K6 ≥13 (%) | 11 (7%) | 3 (6%) | 8 (7%) |
| WFun ≥ 21 (%) | 29 (18%) | 11 (21%) | 18 (16%) |
| SASS ≤ 25 (%) | 13 (8%) | 6 (11%) | 7 (7%) |
AIS: Athens Insomnia Scale, K6: Kessler 6, WFun: Work Functioning Impairment Scale, SASS: Social Adaptation Self-evaluation Scale
In terms of familial relationship with the caregiver from the care recipient’s perspective, children were the most common (74%), followed by spouses (13%). Caregivers living with care recipients accounted for 40% of the participants. The mean number of people cared for by caregivers was 1.1. Caregivers spent an average of four times per week with their care recipients, or 5.9 hours per visit. Nearly half of the caregivers reported that they had been providing caring for the care recipients for more than one year, and 24% of female caregivers had been caring for the care recipients for more than three years (Table 3).
| Caregiver | |||
|---|---|---|---|
|
Total (N=166) |
Men (n=54) |
Women (n=112) |
|
| relationship from the care recipient perspective (%) | |||
| child | 122 (74%) | 41 (76%) | 81 (72%) |
| stepchild | 8 (5%) | 1 (2%) | 7 (6%) |
| spouse | 22 (13%) | 7 (13%) | 15 (13%) |
| sibling | 1 (1%) | 0 (0%) | 1 (1%) |
| parent | 8 (5%) | 3 (6%) | 5 (5%) |
| others | 5 (3%) | 2 (4%) | 3 (3%) |
| living with care recipient (%) | 66 (40%) | 23 (43%) | 43 (38%) |
| number of people cared for, mean | 1.1 (0.5) | 1.0 (0.6) | 1.1 (0.5) |
| number of times per week spent together, mean | 4.0 (3.4) | 4.3 (4.5) | 3.9 (2.8) |
| time spent together per day, hour, mean | 5.9 (6.3) | 4.5 (5.9) | 6.7 (6.4) |
| care duration | |||
| less than 1 month | 22 (15%) | 11 (23%) | 11 (11%) |
| more than 1 month, but less than 3 months | 12 (8%) | 4 (9%) | 8 (8%) |
| more than 3 months, but less than 6 months | 17 (12%) | 7 (15%) | 10 (10%) |
| more than 6 months, but less than 1 year | 23 (16%) | 6 (13%) | 17 (17%) |
| more than 1 year, but less than 3 years | 41 (28%) | 12 (26%) | 29 (30%) |
| more than 3 years | 30 (21%) | 7 (15%) | 23 (24%) |
The care recipients included 74 men and 138 women, with an average age of 79.8 years. The most common diagnosis was mild cognitive impairment (37%), followed by Alzheimer’s disease (35%) and mixed dementia (13%). The mean disease duration was 31.1 months. The mean MMSE and CDT scores were 21.6 and 11.8, respectively. The NPI-Q severity and burden scores were 6.6 and 8.1, respectively. The PSMS was 4.6 (Table 4).
| Characterictic | Care recipients | ||
|---|---|---|---|
|
Total (N=212) |
Men (n=74) |
Women (n=138) |
|
| age, y, mean | 79.8 (7.2) | 79.3 (7.7) | 80.1 (7.0) |
| sex, man (%) | 74 (35%) | 74 (100%) | – |
| diagnosis | |||
| Alzheimer’s dementia | 74 (35%) | 14 (19%) | 60 (43%) |
| Dementia with Lewy bodies | 5 (2%) | 3 (4%) | 2 (1%) |
| Frontotemporal Dementia | 9 (4%) | 3 (4%) | 6 (4%) |
| Vascular Dementia | 8 (4%) | 5 (7%) | 3 (2%) |
| Mixed Dementia | 27 (13%) | 11 (15%) | 16 (12%) |
| Mild Cognitive Impairment | 78 (37%) | 29 (40%) | 49 (36%) |
| Others | 11 (5%) | 9 (11%) | 2 (1%) |
| disease duration, m, mean | 31.1 (31.8) | 26.4 (28.8) | 33.7 (33.2) |
| MMSE | 21.6 (5.6) | 21.1 (6.0) | 21.8 (5.3) |
| CDT | 11.8 (3.4) | 11.4 (3.5) | 12.0 (3.3) |
| NPI-Q | |||
| severity scale | 6.6 (5.9) | 5.9 (5.0) | 7.0 (6.4) |
| distress scale | 8.1 (8.6) | 7.2 (6.8) | 8.6 (9.4) |
| PSMS | 4.6 (1.8) | 4.5 (1.9) | 4.6 (1.7) |
| IADL | – | 2.8 (1.6) | 4.8 (2.0) |
MMSE: Mini-Mental State Examination, CDT: Clock Drawing Test, NPI-Q: Neuropsychiatric Inventory Questionnaire, PSMS: Physical Self- Maintenance Scale, IADL: Instrumental Activities of Daily Living
The most common status of long-term care insurance among the care recipients was unapplied (33%), followed by those with care level 1 (26%), those with support required 1 (9%), and those considering applying (9%). The use of care support status is in the following order: day services (30%), day care (9%), and home visit care (8%) (Table 5).
| Care recipients | |||
|---|---|---|---|
|
Total (N=212) |
Men (n=74) |
Women (n=138) |
|
| long-term care insurance levels | |||
| unapplied | 70 (33%) | 33 (45%) | 37 (27%) |
| considering applying | 18 (9%) | 4 (5%) | 14 (10%) |
| under application | 11 (5%) | 4 (5%) | 7 (5%) |
| support required 1 | 19 (9%) | 5 (7%) | 14 (10%) |
| support required 2 | 14 (7%) | 4 (5%) | 10 (7%) |
| care level 1 | 54 (26%) | 14 (19%) | 40 (29%) |
| care level 2 | 16 (8%) | 7 (10%) | 9 (7%) |
| care level 3 | 6 (3%) | 2 (3%) | 4 (3%) |
| care level 4 | 3 (1%) | 0 (0%) | 3 (2%) |
| care level 5 | 0 (0%) | 0 (0%) | 0 (0%) |
| care support status | |||
| day services | 63 (30%) | 11 (15%) | 52 (38%) |
| day care | 19 (9%) | 4 (5%) | 15 (11%) |
| home-visit care | 17 (8%) | 3 (4%) | 14 (10%) |
| home-visit nursing | 10 (5%) | 2 (3%) | 8 (6%) |
| short stay | 1 (0%) | 0 (0%) | 1 (1%) |
| emergency alert system | 1 (0%) | 1 (1%) | 0 (0%) |
| meal delivery service | 7 (3%) | 0 (0%) | 7 (5%) |
| bathing assistance service | 4 (2%) | 0 (0%) | 4 (3%) |
This study was conducted among working caregivers of relatives with some form of cognitive impairment. Using a questionnaire, caregivers were asked about their health, living, working, and caregiving situations, as well as socio-psychological factors. The survey took approximately 20 min to complete; therefore, caregivers completed the questionnaires when they had time and the questionnaires were collected by mail. The collection rate was 78%, which was higher than that reported in a previous study (47%), which had used a similar method to collect data from caregivers caring for patients with dementia [21].
The average age of the caregivers was 54.7, an age group with a high employment rate in Japan [5]. A previous study also reported the average age of caregivers as 57 years [4].This age group has specialized knowledge and skills and often contributes to the education and mentoring of younger workers. Health issues increase with age, which may require a review of the working styles and environments. Two-thirds of the caregivers were women, a trend similar to that observed in previous studies [22]. Of the caregivers, 74% were married, and the average number of people living together was 2.9, which is higher than the average household size in Japan of 2.2 [23]. Smoking rates among caregivers were 30% for the men and 8% for the women, consistent with the results of previous studies on workers [24]. Men had higher rates of alcohol consumption than women, with about half of them drinking almost every day. The frequency of caregivers who exercised almost daily was 16%, which approximates the reported frequency of 17.3% of Japanese people over 20 years of age who exercise at least five days per week [25].
In addition to the above lifestyle factors, this study used a battery of psychosocial factors, including AIS, K6, WFun, and SASS, all of which have been used across workplaces and populations in previous studies. The AIS comprises 8 items: sleep induction, awakening during the night, problems with waking too early, total sleep duration, sleep quality, well-being during the day, functioning capacity during the day, and sleepiness during the day [26]. About 20% of the adult Japanese population exhibits symptoms related to insomnia, and 39.7% of workers aged 20 years and older have AIS scores of 6 or higher [27]. In this survey, 45.5% of participating caregivers reported insomnia symptoms, a higher frequency than in the general population. Sleep duration was an average 6.3 hours, which is less than the Japanese average of 7.5 hours [28]. Caregivers attended care recipients an average of four times per week, or 5.9 hours per visit, indicating that the time required for both work and caregiving affects sleep time and quality. Awakening an average of 0.3 times per night due to perform caregiving may also have a negative effect on caregivers’ sleeping status.
The K6 is often used in surveys of the general population as an indicator of mental health [29]. Twenty-seven percent of male workers and 33% of female workers report a K6 score of 5 or higher [30], and 10.8% of workers had a K6 score of 13 or higher in a previous study conducted in Japan [31]. Internet surveys conducted by Fujino et al during the COVID-19 pandemic showed that 40% and 9.1% of the respondents had K6 scores of 5 or higher and 13 or higher, respectively [24]. In this survey, 43.9% and 6.7% of the study participants had K6 scores of 5 or higher and 13 or higher, respectively. These results are consistent with those reported by Fujino et al in a similar time frame, suggesting that several subjects experienced mild-to-moderate psychological distress compared to the results of previous studies that were conducted prior to the COVID-19 pandemic; however, their condition was not extremely poor. Fujino et al developed the WFun scale to assess work dysfunction in workers with health problems. The WFun score ranges from 7 to 35, with approximately 20% of participants reporting a score of 21 or higher [13]. This study shows that 17.8% caregivers had a WFun score of 21 or higher, consistent with previous studies, and not a conspicuous work dysfunction. Previous studies reported SASS scores of 36.1 for healthy controls, 33.7 for depressed patients who are employed, and 25.2 for depressed patients who are not employed [14]. In this survey, about 10% of caregivers had worsened social adjustment disorders, aligned with the level of depressed patients who were not working.
A 2022 survey in Japan reported that the most frequent caregivers were spouses living together (22.9%), children living together (16.8%), family members and others living separately (11.8%), and spouses of children living together (5.4%) [32]. The frequency of caregiving by a cohabitant is 45.9% [32]. In this survey, children were the more frequent caregivers and, somewhat less frequently, caregivers living together. This may be due to the different tabulation methods and the fact that this survey was limited to those who were working while providing care. The daily time required by caregivers for direct assistance and support was 2–4 hours for 24.9%, 1–2 hours for 20.2%, and 6 hours or more for 17%, while the time required for looking after the care recipient was 6 hours or more for 39.4%, 2–4 hours for 16%, and 4–6 hours for 13.4% [33]. Although the questions in this survey are different and cannot be compared, the time spent per day was relatively brief and may be related to balancing work with other daily activities. Differences in the conditions of care recipients may also influence the results. The duration of care was reported as 38.6% for more than 4 years, 14.9% for 3–4 years, 17.1% for 2–3 years, 14.3% for 1–2 years, and 7.8% for 1 year or less in a previous study [33]. In this survey, about half of the cases were within one year, and this may have been influenced by the stage of disease progression in the care recipients.
The prevalence of dementia and mild cognitive impairment in Japan are estimated at 10.9% and 15.3%, respectively [34]. Alzheimer’s disease is known to be more frequent and more common among women than among men [35]. Mild cognitive impairment and Alzheimer’s disease were more prevalent in this study, consistent with previous studies. The length of care time that is needed in Japan is approximately 8 years for men and 12 years for women. Our study population had a relatively mild degree of cognitive impairment, with a disease duration of less than three years and an average MMSE score of 21.6. While some did not use the long-term care insurance system, others had declining ADLs and IADLs or behavioral psychological symptoms and used assistance through the long-term care insurance system. Women received assistance from long-term care insurance more frequently than men did, with most of them using day services. This is consistent with the high cost of day services among the long-term care insurance benefits for in-home residents [36].
A limitation of this study is that the support provided by the long-term care insurance system, as well as its effects on working caregivers, may vary for individuals with moderate to severe dementia. Further studies should include care recipients with a broader range of severity levels and their working caregivers.
This study outlines the protocol and results of a cohort study of patients with dementia and their working relatives who care for them. We plan to use this study to examine the impact of caring for a relative with dementia on the working caregiver’s health, life, and employment.
Present members of the Sustaining for Aging dementia relatives Support And Employment (SASAE) project are, in alphabetical order, Dr. Atsuko Ikenouchi (current chairperson), Dr. Hisashi Eguchi, Dr. Naomichi Okamoto, Dr. Reiji Yoshimura, Dr. Shinsuke Hamada, Dr. Shogo Kitagawa, Dr. Shunya Maruyama, Ms. Tomomi Matsumoto, Dr. Yoshihisa Fujino, and Dr. Yuki Konishi. All the members are affiliated with the University of Occupational and Environmental Health, Japan.
None.
Conceptualization: Atsuko Ikenouchi, Yoshihisa Fujino, Hisashi Eguchi, Reiji Yoshimura. Methodology: Atsuko Ikenouchi, Yoshihisa Fujino, Hisashi Eguchi, Reiji Yoshimura. Software: Atsuko Ikenouchi, Yoshihisa Fujino. Validation: Yoshihisa Fujino. Formal Analysis: Atsuko Ikenouchi, Yoshihisa Fujino. Investigation: Atsuko Ikenouchi, Tomomi Matsumoto, Naomichi Okamoto, Shinsuke Hamada, Shogo Kitagawa, Shunya Maruyama, Yuki Konishi, Reiji Yoshimura. Data Curation: Atsuko Ikenouchi, Yoshihisa Fujino. Writing – Original Draft Preparation: Atsuko Ikenouchi. Writing – Review and Editing: Yoshihisa Fujino, Hisashi Eguchi, Reiji Yoshimura. Visualization: Atsuko Ikenouchi, Yoshihisa Fujino. Supervision: Atsuko Ikenouchi. Project Administration: Atsuko Ikenouchi. Funding Acquisition: Atsuko Ikenouchi.
This study was supported by JSPS KAKENHI (Grant Number: JP22K10572).
Data are not available owing to ethical restrictions and the need to preserve the participants’ anonymity.
