Youth suicide represents a critical public health issue globally, with South Korea experiencing particularly high rates. According to the World Health Organization, suicide among individuals aged 15~19 years is the fourth leading cause of death worldwide [1]. Although the youth suicide rate in South Korea has shown a slight decline, it remains among the highest in the Organisation for Economic Co-operation and Development countries [2,3]. This highlights the urgent need for societal attention and academic research to address this pressing issue.

Research has demonstrated that factors contributing to suicidal ideation vary across life stages [4,5]. Adolescence, in particular, is a period marked by significant cognitive, psychosocial, biological, and environmental changes, all of which can influence mental health outcomes [6]. Recent studies indicate that the trajectories of suicidal ideation differ between early and late adolescence, with each stage characterized by distinct risk and protective factors [7]. This aligns with developmental theories suggesting that early adolescence (typically middle school) and late adolescence (typically high school) differ significantly in developmental, educational, and social contexts [8], which may result in distinct risk profiles for suicidal ideation.

During early adolescence, social dynamics undergo substantial transformation. Adolescents in this stage spend increasing amounts of time with peers, a factor that profoundly influences their social and emotional development [9]. This period is marked by vulnerability to mental health challenges, exacerbated by psychological and emotional instability stemming from pubertal changes, increased sensitivity to peer evaluation, and heightened emotional reactivity in expanding peer-driven social networks [6]. In contrast, late adolescence introduces challenges associated with academic pressures, such as preparing for college entrance exams and making career decisions. These pressures, coupled with societal expectations for high academic performance, can lead to elevated levels of stress and psychological strain [10]. While cognitive and emotional regulation systems continue to mature during this stage, heightened expectations often amplify stress and anxiety [11]. These contrasting stressors underscore the developmental distinctions between early and late adolescence.

The multifaceted factors contributing to adolescent suicide include mental health challenges, academic stress, familial conflicts, social isolation, and the pervasive influence of social media [12]. The impact of these factors varies between middle school (early adolescence) and high school (late adolescence) students. For example, middle school students are at greater risk of suicide when experiencing parental abuse [13]. Key factors influencing suicidal ideation in this group include life challenges, depression, social support, daily stressors, and school violence [14]. For high school students, prevention strategies should prioritize mental health improvements by addressing delinquency and depression while considering gender differences [15]. Moreover, self-perceived academic achievement significantly influences suicidal tendencies in high school students, with lower perceptions of academic success strongly associated with severe suicidal thoughts [16]. While depression is a major predictor of suicidal ideation across all adolescent stages and genders, its impact intensifies during late adolescence. Conversely, self-efficacy is a significant predictor in early adolescence but diminishes in relevance as depression becomes a stronger predictor in late adolescence [17].

Research on adolescent suicide is further complicated by the unique sociocultural and educational contexts in South Korea. The nation’s examination-oriented education system, high academic stress, and competitive societal atmosphere contribute to distinct suicide-related challenges [18]. Age-related differences in suicidal ideation and behavior are well-documented [19], yet there remains a critical gap in understanding how these differences manifest within Korea’s specific sociocultural framework.

An important limitation of existing research is its failure to fully reflect developmental differences in suicide risk. The trajectory of adolescent suicide is multidirectional and reversible [20], with varying influences at different developmental stages [21]. However, most studies analyze adolescents as a uniform group, limiting the development of tailored prevention and intervention strategies that account for developmental characteristics. There is a lack of research examining how suicide-related factors differ between middle and high school students in South Korea.

To address this gap, this study aims to investigate differences in the factors influencing suicidal ideation among middle school and high school students. Specifically, the study will analyze sociodemographic variables (e.g., sex, economic status), academic performance, health risk behaviors (e.g., smoking, drinking), and mental health indicators (e.g., perceived stress, depression, loneliness, anxiety) to assess their impact on suicidal ideation by school level. By identifying these developmental differences, this study seeks to provide empirical evidence for the creation of targeted suicide prevention and intervention strategies tailored to the needs of each developmental stage.

This study highlights significant differences in suicidal ideation between middle school and high school students. The prevalence of suicidal ideation was higher among middle school students (15.4%) compared to high school students (13.1%). This pattern aligns with the 2020 16th KYRBS, which reported a prevalence of 11.5% among middle school students and 10.2% among high school students. The findings indicate an overall upward trend in suicidal ideation following the coronavirus disease 2019 pandemic, with middle school students consistently exhibiting higher rates of suicidal thoughts than their high school counterparts [25]. This disparity may reflect developmental differences in vulnerability and coping capacities during adolescence.

The study also revealed a significant gender disparity in the prevalence of suicidal ideation, with female students exhibiting higher rates than their male counterparts in both middle and high school. This disparity was particularly pronounced among middle school students, consistent with findings from Nock et al. [26], who reported that suicidal ideation tends to emerge predominantly during early adolescence (13~14 years old) and that females are more likely than males to experience suicidal thoughts. These findings suggest that early adolescence may represent a critical period for gender-sensitive interventions targeting suicidal ideation.

The relationship between academic performance and suicidal ideation showed notable differences between middle and high school students. Among middle school students, a linear pattern was observed, with lower academic performance consistently associated with higher rates of suicidal ideation. This suggests that academic underperformance during early adolescence may directly increase psychological distress or feelings of hopelessness, leading to suicidal ideation [27]. Conversely, in high school students, the relationship followed a non-linear pattern, with middle-performing students exhibiting the lowest prevalence of suicidal ideation. Students with lower academic performance had the highest prevalence (16.0%), potentially reflecting frustration or hopelessness associated with academic struggles. Students at the top of the academic hierarchy also showed a relatively higher prevalence (12.2%), which may be attributed to the intense pressure to excel academically and secure college admission. These findings underscore the importance of addressing both academic stress and its psychological consequences for students across different educational stages. Lee and Kim [28] similarly emphasized that academic performance and engagement influence changes in suicidal ideation, highlighting the need to consider psychological factors and students’ attitudes toward academics in interventions aimed at reducing suicidal ideation. Economic status was another significant factor influencing suicidal ideation, with lower economic status associated with higher prevalence rates among both middle and high school students. The effect was particularly pronounced among middle school students, corroborating findings from Dupéré et al. [29], who demonstrated that poverty exerts a stronger influence on suicidal ideation and attempts during early adolescence (12~15 years old) than during late adolescence (16~19 years old). These findings suggest that early adolescence represents a period of heightened vulnerability to environmental stressors such as economic hardship, reflecting developmental differences in the ability to cope with such challenges.

The association between risk behaviors, such as smoking and drinking, and suicidal ideation was evident in both middle and high school students, with stronger effects observed among middle school students. This aligns with the findings of Cho et al. [30], who reported that early initiation of substance use, particularly during middle school, significantly increases the risk of suicide later in life. These findings underscore the importance of implementing early intervention and prevention programs to address substance use among middle school students. Collaborative efforts between schools and communities to develop and deliver comprehensive prevention programs targeting tobacco and alcohol use in early adolescence could play a critical role in reducing youth suicide rates.

Mental health factors, including depression, loneliness, and anger, were strongly associated with suicidal ideation across all age groups, but the association was a bit more pronounced among high school students. These findings are consistent with those of Nock et al. [26], who emphasized the heightened influence of mental health factors during early adolescence .This underscores the importance of mental health screening and early intervention during this developmental stage. Strengthening mental health services in schools and communities, along with the establishment of systems for early identification and support for emotional difficulties, particularly for high school students, may be a highly effective strategy for suicide prevention.

The findings of this study indicate that suicide prevention strategies for youth should be differentiated by age group, considering the unique developmental, social, and psychological factors that influence suicidal ideation during middle and high school. Future research should aim to elucidate the underlying mechanisms driving these age-specific differences and to develop targeted, evidence-based interventions that address the distinct challenges faced by adolescents at each developmental stage.

The aim of this study was to investigate the factors contributing to suicidal ideation among middle and high school students in South Korea. The findings reveal distinct patterns of risk factors between the two age groups. Middle school students exhibited a higher prevalence of suicidal ideation compared to high school students, aligning with national trends and reflecting developmental differences in vulnerability and coping mechanisms during early adolescence.

For middle school students, substance use behaviors, such as smoking and drinking, along with lower academic performance and economic hardship, were identified as significant predictors of suicidal ideation. These findings emphasize the need for early intervention and prevention programs targeting risk behaviors and environmental stressors in early adolescence. In contrast, for high school students, mental health issues, particularly depression and anxiety, were more prominent risk factors for suicidal ideation. Severe anxiety showed the strongest association, underscoring the importance of prioritizing mental health screening and providing accessible support systems to address psychological distress in high school populations.

These results highlight the necessity of age-specific and context-sensitive suicide prevention strategies for adolescents. Tailored interventions should reflect the developmental, social, and psychological differences between middle and high school students to maximize their effectiveness. Additionally, schools and policymakers should collaborate to implement comprehensive programs that address both behavioral and mental health challenges, while future research should focus on elucidating the mechanisms driving these age-specific differences and developing evidence-based interventions to reduce suicidal ideation among adolescents.