Suicide is a leading cause of death worldwide, accounting for more than 700,000 deaths annually (1). A large amount of resources is being invested in suicide prevention and many approaches are being studied. Among the OECD countries, South Korea has had the highest suicide rate, and the government has been researching policies to address this issue (2). However, suicide rates remain high. Suicide is an important public health issue in all age groups, but the severity of the problem is particularly increasing in the middle-aged population. The suicide rate of middle-aged adults in the United States has increased by >40% over the past 20 years, whereas there has been little change in other age groups (3). A similar trend in suicide rates has also been observed in South Korea (4). Middle age is a crucial period in terms of professional career and an important point of transition from youth to older age. Thus, the increasing suicide rate among middle-aged adults is an important public health issue.

Many studies have focused on identifying the risk factors for suicide with the goal of facilitating prevention. Depression has been extensively researched as a risk factor contributing to suicidal ideation and behavior, and is consistently included in suicide risk assessments and guidelines (5, 6). Suicidal behavior is a symptom of depression, and depression is the most common mental illness in patients who exhibit suicidal behavior (7). Accordingly, research is being conducted on pharmacological and non-pharmacological treatments for managing depression, as a risk factor for suicidal behavior, and for managing suicidal ideation, which is directly associated with suicidal attempts/death (8). Exercise is an alternative treatment option (9, 10) but regular and intense exercise therapy is burdensome for most patients. Walking is a form of exercise that imposes a smaller burden on patients. Growing evidence suggests beneficial effects of walking on mental health conditions such as depression, anxiety, and psychological stress (11). However, information regarding the duration of walking that provides beneficial effects is lacking. A study on the association between walking and suicidal ideation was limited to a subset of cancer patients (12). Additionally, no results applicable to middle-aged adults were reported.

The current study aimed to examine the associations of walking exercise with depressed mood and suicidal ideation in middle-aged individuals in South Korea. We also investigated whether the effects of walking on depressed mood and suicidal ideation vary by walking duration. To our knowledge, this is the first study to examine the effects of walking on depressed mood and suicidal ideation in a general middle-aged population.

In total, 24,269 people participated in the KNHANES during the study period, including 7,600 middle-aged participants (40–60 years old). After excluding people who did not complete the depressed mood and suicidal ideation survey (323 people) or walking activity survey (391 people), we analyzed the data of 6,886 people (Figure 1).

The results of this nationwide cross-sectional study of 6,886 middle-aged adults in South Korea suggest a beneficial effect of walking on depressed mood and suicidal ideation in this population. Regularly walking (> 5 times per week) was associated with a 40% reduction in depressed mood and a > 70% reduction in suicidal ideation compared to not walking at all among middle-aged adults. Suicidal ideation decreased with a greater number of walking days, though not significant for 1–2 days/week and 3–4 days/week. Depressive mood showed a numerical decrease for 1–2 days/week and 3–4 days/week, although it was not statistically significant. These effects were observed after adjusting for various factors such as age, smoking status, alcohol consumption, education level, occupation, household income, marital status, sleep duration, and comorbidities. Interestingly, the duration of a single exercise occasion and the total exercise time during the week did not modulate the results. In other words, exercising for a long period on one occasion did not have a beneficial effect; benefits were only seen when regularly exercising (> 5 times per week). Thus, it is important walk almost every day, even for a short time. Sex-stratified analysis revealed similar findings for depressed mood and suicidal ideation in men, but only suicidal ideation showed significant association in women.

Our results share some similarities with previous studies on the association between walking and mental health. A study of older females reported that walking for 50 min, 3 times per week, helped reduce depression (21). A meta-analysis of eight randomized controlled trials reported a clinical effect size of −0.86 for walking to treat depression (22). Exercise increases central arousal and releases various neurotransmitters, such as dopamine, epinephrine, norepinephrine, serotonin, and endorphins (23–25). This release of neurotransmitters can improve mood, emotional functioning, and stress reactivity (26). Exercise also upregulates growth factors, such as brain-derived neurotrophic factor, which is associated with depression and suicidal ideation (26–28).

To understand the need for suicide prevention measures in middle-aged adults, it is important to examine the recent rise in suicide rates in this group, including in terms of the potential impact on society. The Great Recession, which occurred in the United States from 2007 to 2009, had a global economic impact, and also affected the mental health of economically active middle-aged individuals (3). Additionally, the rapid growth of South Korea since the 1998 financial crisis, which was aided by the International Monetary Fund, has imposed economic and employment pressure on young and middle-aged individuals (29, 30). Even without these issues, middle-aged individuals often face pressure to achieve in various aspects of life. In Erikson’s original psychosocial stages, middle age is characterized as either generative or stagnated, and recent studies have emphasized the importance of engaging in generative activities during this life stage (31). Middle-aged individuals play important roles in society, contributing to the workplace, parenting, and various community activities (32). Hence, the rising suicide rate among this population is a grave concern; it could potentially impose a major burden on society, thus making it a public health issue.

Previous studies have identified suicidal ideation and depression as significant risk factors for suicide among middle-aged adults (8, 33). Although pharmacotherapy is considered the primary treatment in most cases, non-pharmacological therapy is often used concurrently, or even in preference to pharmacotherapy (due to side effects, poor compliance, and the patient’s health status) (34). Exercise has been proposed as an alternative therapy for depression and suicidal ideation (9, 10). In a previous study, 30 min of walking, 4 times a week for 4 weeks helped to increase the patients’ adaptive coping strategies (15). In line with this, our supplementary analysis also showed that walking of >30 min for more than 5 times a week was associated with a decrease in suicidal ideation. However, an issue with exercise therapy is that patients who are depressed or have suicidal ideation often lack motivation, and the idea of having to start to exercise in earnest can be daunting. Therefore, it is more interesting and encouraging that significant results were obtained with only a short time of exercise of more than 10 min, as in our study. We hope that our results highlight the usefulness of walking and help patients become motivated. Walking is an exercise that requires no equipment and can be easily started in the neighborhood or during commuting hours, thus making it relatively accessible (35). Our findings suggest that regular walking, regardless of duration, has a beneficial effect on middle-aged individuals, and may be especially helpful for those who have various responsibilities at work and home. Walking is a simple way to maintain mental health.

As this study was based on national health data, several points should be considered. First, because the data were not collected specifically for this study, it was difficult to apply data collection strategies commonly used in research (36). Moreover, as this was a cross-sectional study, it was not possible to identify causal relationships. Our interpretation of the results may have been reversed; it could also be that individuals without mood symptoms could walk more. Also, the data on exercise, depressed mood, and suicidal ideation relied on self-report measures; thus, recall bias could have affected the results. Finally, the family type was not included in the adjusted variables, because of the concern of possible multicollinearity with the marital status.

To the best of our knowledge, this is the first study to investigate the associations of walking with depressed mood and suicidal ideation in middle-aged adults. Regardless of the duration of exercise, walking >5 times per week helped reduce depressed mood and suicidal ideation in middle-aged men, and suicidal ideation in middle-aged women. Clinicians could recommend walking as a non-pharmacological approach to reduce patient suicidal ideation. Short walks could serve as a useful starting point for patients with serious mental health issues, such as depressed mood and/or suicidal ideation.

In this nationwide cross-sectional study of middle-aged adults in South Korea, walking  >5 times per week was helpful for mental health, regardless of duration. The study found an association between walking and reduced symptoms of depressed mood and suicidal ideation in middle-aged men, and a significant reduction in suicidal ideation in middle-aged women.

The original contributions presented in the study are included in the article/Supplementary material, further inquiries can be directed to the corresponding author.

The studies involving humans were approved by the Institutional Review Board of the KCDC (Korea Disease Control and Prevention Agency) approved the KNHANES VII (approval no. 2018-01-03-P-A). The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.

YK and YC contributed to data analysis and writing the manuscript. GK, CH, SS, and HR gave critical opinions on the study design, and the manuscript. JM contributed to data analysis. SH contributed to interpreting the results and supervised the entire process. All authors contributed to the literature review, study design, data interpretation, and approved the final manuscript.

This work was supported by the Soonchunhyang University Research Fund (2023–0018). The Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI) funded by the Ministry of Health &Welfare, Republic of Korea (grant number: HR22C173401).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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