Depression is a serious health concern among adolescents, being a significant contributing factor to suicide in that demographic [1, 2]. Indeed, 17.7% of adolescents have seriously contemplated suicide because of depressive symptoms [2]. Depression is more prevalent among female adolescents than males [3]. In South Korea, 27.8% of female adolescents and 19.7% of male adolescents nationwide reported experiencing depressive symptoms severe enough to interfere with normal daily life patterns [4]. Previous studies that investigated factors associated with depression among female adolescents in Korea, found that problem-solving abilities, interactions with family members, peer relationships, negative body-image, and satisfaction with school life, life stress, and sense of coherence were significant factors in depression among them [5, 6]. Kim [7] investigated factors associated with depression and found them to be different in urban and rural areas. Experience of school violence and parenting attitudes were significantly associated with depressive symptoms among urban adolescents, whereas subjective income level and stress from family were significant among rural adolescents. Most prior studies that compare depression level and differentiate factors between urban and rural areas have targeted an older population [8, 9]. However, a few studies have been conducted targeting adolescents that differentiate factors of depression between urban and rural areas [7] although studies that apply a theoretical framework targeting female adolescents have been scarce. Therefore, we sought to investigate factors associated with female adolescents' depressive symptoms and compare those factors between urban and rural areas by applying the Ecological Models of Health Behavior framework [10] to develop tailored interventions considering their social and environmental contexts.

The Ecological Models of Health Behavior explain that multiple levels of factors influence health behavior, including intrapersonal (biological, psychological), interpersonal (social, cultural), organizational, community, and public policy levels. Furthermore, these multiple factors interact across different levels [10]. Individual perceptions or emotions are intrapersonal, while dyadic or family influences such as relationship satisfaction or social support are interpersonal. The organizational and community levels are factors that affect large groups such as community norms and social capital [11]. Applying a socio-ecological model, Gu et al. [12] found that self-stigma was significantly associated with severe depression among sex workers in China. Therefore, the Ecological Models of Health Behavior framework can be an excellent guide for multi-level investigation of factors affecting depressive symptoms in female adolescents.

This study aims to describe the prevalence of depressive symptoms among female adolescents in urban and rural areas, and compare factors associated with depressive symptoms in both areas in terms of the intrapersonal (grade, academic achievement, general life happiness, perception of health, worry/anxiety, mood/suicidal ideation, and academic/internet-related problems), interpersonal (family members living together, source of stress, and peer problems), and organizational (satisfaction with school life and rule violations) levels. Satisfaction with school life and rule violations variables are considered individual perceptions and delinquent behaviors, however these variables are predominantly influenced by organizational culture, and directly associated with school policy and regulations [13]. Therefore, we included satisfaction with school life and rule violations as organizational level factors.

We examined factors associated with depressive symptoms among female adolescents in Korea, including multiple levels of influence described in the Ecological Models of Health Behavior framework, differentiating those factors between urban and rural areas. Intrapersonal, interpersonal, and organizational level factors were significantly associated with depressive symptoms among female adolescents. Some of the significant factors differed between urban and rural groups. Among female adolescents in urban areas, intrapersonal level characteristics (general life happiness, perception of health, worry/anxiety, and mood/suicidal ideation), and interpersonal level characteristics (stress associated with school performance) were significant, whereas in rural areas, intrapersonal level characteristics (general life happiness, worry/anxiety, mood/suicidal ideation, and academic/internet related problems) and organizational level characteristics (rule violations) were significantly associated with depressive symptoms. Our study is unique in that we analyzed factors associated with depressive symptoms in female adolescents by applying the Ecological Models of Health Behavior framework, and differentiated those factors between urban and rural areas.

Using the BDI, we found that 15.7% of urban female adolescents and 22.9% of those in rural areas had moderate or severe depressive symptoms. An accurate assessment of mental health problems and appropriate interventions are required for high-risk groups of adolescents because depression is a major risk factor for suicidal ideation and suicide attempts, and depression in adolescence can advance to Major Depressive Disorder in adults [1, 3].

Consistent with a previous study [8], mean scores for depressive symptoms were higher in rural areas than in urban areas. The prior study reported that middle school students in rural areas had a significantly higher depression score than those in urban areas [8]. Another study reported that adolescents in rural areas experience more stress and a lower quality of life than those in urban areas [20]. The authors contended that the gap between urban and rural differences is greater in developing countries than in developed countries, a fact that might be attributed to diverse modernization of the education system in urban and rural areas [20]. A relatively inferior education system in rural areas could lead to a lower chance of gaining increased economic status that might be associated with lower psychological wellbeing [20]. Improvements in the education system in rural areas might promote psychological health among adolescents. In addition, in the development of psychosocial health programs, adolescents in rural areas should be a priority target for intervention.

Perception of health, worry/anxiety, mood/suicidal ideation, and academic/internet related problems included in intrapersonal level characteristics were significantly different between two groups. Among these, general life happiness, worry/thoughts, and mood/suicide were significantly associated with depressive symptoms in both the urban and rural groups. Similar to our study, a previous study found that students with depressive symptoms had lower self-reported happiness and lower health status than those without depressive symptoms [21]. Those results may indicate that adolescents with depressive symptoms exhibit more problem behaviors or frequent exhibition of problems behaviors may lead to depressive symptoms. Either way, practitioners should understand that problem behaviors could accompany depressive symptoms. Thus, screening for depression is required for adolescents who exhibit problem behaviors.

We found that academic/internet related problems were significantly associated with depressive symptoms in rural areas only, while rural adolescents reported a higher mean score for academic/internet related problems compared to urban adolescents. Overuse of the internet affects depression in adolescents, and the career crisis of rural students directly affects their overuse of the internet [22]. Other researchers reported that rural adolescents spend more time using the internet and found that internet addiction was associated with depression [23]. A previous study reported that youth with depressive symptoms were more likely to interact with peers only online and found that relationship-oriented internet use had a negative effect on depression [24]. Bak [25] contended that lack of recreational facilities and cultural spaces in rural areas are partly responsible for higher prevalence of internet addiction among rural adolescents in Korea. Therefore, interventions to decrease academic/internet related problems such as off-line recreational activities may improve rural adolescents' depressive symptoms.

Interpersonal level characteristics that affect depression were found to differ between urban and rural groups. In urban areas, stress associated with school performance was significantly associated with depressive symptoms in our study. A previous study found that urban students had more aspirations for advanced education and that they outperformed those in rural schools at both the primary and secondary levels [26]. Other researchers also found that in urban areas, parents have increased expectations for the academic achievement of their children, adolescents themselves have higher academic aspirations, and adolescents actually had higher academic grades than their peers in rural areas [27]. These parental and adolescent aspirations for higher academic grades could cause depressive symptoms because of immoderate competition among adolescents in urban areas.

We found significant associations between rule violations and depressive symptoms of organizational level characteristics in rural adolescents. A previous study also reported similar results [28]. The authors found that rural adolescents were more likely to engage in juvenile delinquency and school violence than urban adolescents, and contended that adolescent counseling centers and violence prevention centers are scarce in rural areas compared to urban areas. Thus, rural adolescents are more vulnerable to conduct disorders [29]. Childhood psychopathology is often conceptualized in two broad categories: internalizing problems such as anxiety and depression, and externalizing problems such as aggression, hyperactivity, and delinquency. Both internalizing and externalizing problems (depression and conduct disorders) can co-exist upon emergence of precipitating factors in children and youth [28]. Therefore, practitioners should be aware that adolescents who commit frequent rule violations might have comorbid psychological health problems.

This study is significant in that the influence of environmental factors is considered by applying the ecological model to depression related factors in female middle school students. In addition, it has confirmed that depressive factors related to urban and rural females are different. Therefore, it is necessary to consider the environmental factors of urban and rural areas while developing intervention for middle school students.

The limitations of this study include the convenience sampling method. Careful attention should be made when generalizing results. In addition, our study cannot exclude social desirability bias in some of the questions or recall bias because data were gathered using a self-report method. Finally, the cross-sectional study design provides no causal relationship between depressive symptoms and independent variables. Our study may not depict current information because it took considerable time between the data collection and analysis. However, this is a comprehensive multisite study, thus it provides important messages for female adolescents' mental health. Meanwhile, repeated studies are required to portray the current status of depressive symptoms among adolescents including mental health and problem behaviors.

Our study compared the prevalence of depressive symptoms and differentiated factors associated with them in female adolescents between urban and rural areas based on the Ecological Models of Health Behavior framework. We found that multiple levels of factors were associated with depressive symptoms, and those significant factors differed between urban and rural female youths. In addition, results reveal that factors associated with depressive symptoms differ between urban and rural groups. Rural female adolescents are more vulnerable to mental health and problem behaviors than their urban peers. They require priority attention and organizational and community level interventions including counseling and prevention programs.

In addition, our results indicate that depressive symptoms are associated with multiple level characteristics. Therefore, when assessing suicidal ideation and depression among middle school students, a macroscopic approach is required at multiple levels such as intrapersonal, interpersonal, and organizational. Moreover, because psychological health problems and conduct disorders may co-exist, assessments should consider both mental health and delinquent behaviors when screening high-risk groups. In particular, the various intrapersonal factors that are analyzed that affect adolescent depression in both urban and rural areas should be closely monitored in relation to suicidal ideation.