The surge in mental health problems among adolescents globally presents a pressing societal concern (1–5). Sweden is not exempt from this development (6). For example, over recent years there has seen a substantial rise in the number of contacts made to the health care system by adolescents reporting an array of mental health problems (7). This is substantiated by an accompanying rise in drug prescriptions for depression and anxiety. Despite these increasing rates, it is pertinent to note that a significant number of adolescents refrain from seeking support or have long help-seeking trajectories (8, 9). In broad terms, paradoxically, adolescents who suffer from more severe mental health problems may be less inclined to seek help (10) and the increase in healthcare utilization, which is seen in Sweden, is mainly driven by adolescents with less severe forms of mental health problems (11).

This development has prompted researchers to seek deeper insights into the factors influencing adolescents’ mental health and help-seeking behaviours. In this endeavour, there is a need for a more nuanced approach to mental health assessment and reporting than is presently the case (12). One reason for this pertains to the increased reporting of mental health problems among adolescents, which dilutes the previous benefits of using threshold values to determine what level of mental health problems should raise concern. There is an urgent need to develop strategies and tools to better distinguish between normal responses to the stressors of life that adolescents naturally face during their development years and those mental health problems that require professional support and treatment. One factor of interest that continues to soar in mental health research is social capital (13, 14). The concept of social capital connects to the social dimension of mental health and refers to the sum of resources that reside within social networks (15) that its members contribute to, benefit from and are affected by.

Resources embedded in social networks have been identified as important for the mental health of adolescents (16). It is well known that social network involvement provides various forms of social support that could decrease stress and thus benefit mental health outcomes (17, 18). Further, social networks could benefit mental health by providing opportunities to learn new skills and by giving a sense of belonging and meaningfulness. In addition, involvement in social networks could influence mental health and help-seeking through the influence of peers as role models for behaviour (19). However, social capital comes in different forms, which might have different effects on health. Theorists, such as Bourdieu, Coleman and Putnam, put social capital on the map of social sciences during the early 90s. Although protagonists of social capital, they take different disciplinary perspectives. While Bourdieu (15) emphasizes social hierarchies, mutual recognition and personal profit as preservers of social reproduction in society, Coleman (20) and Putnam (21) share a more optimistic view of social capital that relies upon reciprocity and democratic engagement. For adolescents, Bourdieu’s view interprets into social structures based on social status, behaviour and norms, as well as preconceptions and expectations from both peers and adults. The other perspective can be exemplified through mutual and unconditional support and trust within a friend network or within the family, enjoy spending time with like-minded and feeling safe within a context or group, building on a reciprocal and positive view of people in general. It is important to consider these differing perspectives when conceptualizing social capital for adolescents, while being responsive to the implications of the transformation of adolescents’ social arenas, seen over the past decade. Regardless of which perspective seems more appealing, the commonalities as we see it lie within the importance of social networks “for getting on and getting ahead in life” (22).

The concept has a cognitive and a structural dimension, consisting of bonding, bridging and linking ties that manifest through norms, behaviours, and attitudes (23). Bonding social capital consists of strong ties among people in homogenous networks, which can strengthen common identities and function as a source of help and support among the network members (24). Bridging social capital, instead consists of weaker ties among people in heterogeneous networks, which can serve as an important source of information and resources (21, 25). Linking social capital in the adult population often refers to inter-hierarchical ties, but this has not been given much attention with reference to adolescents. Instead, a broader notion of bridging social capital has been suggested to include the hierarchical ties of linking social capital (22).

Evidently, social capital is a broad and multidimensional concept. Overall, adolescents have been less included in the conceptualization of the concept (26), suggesting that social capital has generally been considered a biproduct of childhood that may benefit them in the future rather than a useful asset during childhood (27). The “asset approach” to social capital acknowledges adolescents as active agents in shaping their social networks (14) and recent research highlights the importance of incorporating this view for better understanding of the link between social capital and adolescent mental health (28).

The connection between social capital and mental health is complex and previous attempts to establish a clear causal link where a decline in social capital precedes poor mental health have provided limited evidence (29, 30). This is somewhat expected given the multidimensionality of social capital and its embeddedness into the social dimension of mental health, in addition to the multifactorial origins of mental health problems and the interplay of hereditary factors in mental illness incidence (31).

There are resources within adolescents’ social relationships and networks that appear universally desirable. Both theoretical underpinnings (22) and empirical research (16) indicate that trust, sense of belonging, connectedness, reciprocity, and support help shape the mental health of adolescents as they transition into adulthood. Adolescents themselves describe that by having access to safe spaces, to feel connected to networks that nurture sociability, and maintaining control in social interactions are important aspects of these resources (28). These components emphasize the importance of fostering supportive relationships and cultivating a sense of belonging for adolescents.

In the intricate landscape of studying the interplay between social capital and mental health among adolescents, a challenge lies in the translation between theoretical conceptualization and a valid operationalization of the concept in measurement. Existing research highlights the complexities and current limitations in capturing the multidimensional aspects of social capital that resonate uniquely with adolescents (26). There appears to be a dearth of instruments that effectively encapsulate the constructs of social capital and the breadth of relevant social contexts specific to adolescents underscores the necessity for methodological advancements. While previous studies have succeeded in translating social capital theory into measurement techniques for certain constructs of social capital (32, 33), a more inductive and comprehensive approach may be required to align measurement strategies with the dynamics of adolescents’ social networks of today. Another challenge lies in the transferability of measurement between different social cultures, both within and between nations and groups. What resources are accessible and most prominent may differentiate depending on social norms, perhaps especially in relation to mental health. This challenging endeavour promises to pave the way for a nuanced understanding of how social capital influences mental health, ultimately informing targeted interventions that bridge the gap between theoretical concepts and practical applications for reversing the current trend of adolescent mental health. Fitting previous qualitative work into the frames of social capital theory is a challenging task. Many existing instruments for assessment of social capital have been developed with a top-down approach, grounded in theory and with adolescents as passive recipients. However, a strictly inductive approach to the conceptualization of social capital for adolescents may infer flaws pertaining to content validity. An abductive approach, i.e., an oscillation between existing theory and adolescents’ perceptions and experiences, may therefore provide upsides that both sets the initial boundaries for social capital, but also allows for unique insights within these defined boundaries (34).

An intriguing aspect of the association between social capital and mental health is adolescents’ propensity to seek help. Adolescents grappling with severe mental health problems may be less inclined to reach out for help compared to peers experiencing milder issues that occur naturally during adolescence (11). As adolescents navigate their social environments, the connections they establish and the networks they engage with might serve as crucial determinants shaping their attitudes and behaviours towards seeking help. These relational structures and the resources that reside within them could foster an environment, encouraging of open discussions about mental health problems that nurtures competency in help-seeking. Consequently, adolescents with higher levels of social capital might find seeking help a more viable and normative course of action, thereby enhancing their readiness to access appropriate support, both non-professional and professional. There is, however, an ongoing discussion about the “dark sides” of social capital, where strong bonding networks also nurture “unhealthy” norms and behaviours (35) that may have a diametrically opposite impact on help-seeking behaviours and, it cannot automatically be assumed that higher social capital equates healthy help-seeking behaviours. In addition, mistrust of public authorities, including health care, can grow within strong bonding social networks (36). On the contrary, Myeong and Seo (36) also show that bridging ties may help strengthen the trust for public authorities. Connected to this, bonding networks might foster norms of “taking care of their own problems” rather than seeking help from professionals and health care. Paired with more severe mental health problems and a lesser inclination to seek help, this poses a delicate problem in need of a thorough investigation in empirical research. Resources such as trust may have different meaning in relation to help-seeking depending on the norms that reside in social networks (37). The cognitive and structural components of social capital may also play different roles. While cognitive dimensions can both limit and foster awareness of mental health issues, structural dimensions enable connections through which adolescents access tangible resources and guidance, especially through bridging social capital (36). In unravelling the nuances of this association, we open up an avenue for valuable insights that could contribute to enhancing mental health care for adolescents.

As for mental health help-seeking within the adolescent group, validated instruments are rarely employed in research. Instead, single-use measures or vignettes tend to be utilized (38) and few instruments that assess help-seeking focus on capturing knowledge on available help (39). Moreover, there seems to be equal interest given to the frequency of measuring attitudes and intentions, as to assessing actual previous help-seeking behaviour (40). Instruments focusing on help-seeking among adolescents commonly concentrate on four facets: attitudes towards seeking help, intentions to seek help, fears related to treatment concerning help-seeking, and barriers to help-seeking (38). A comprehensive help-seeking instrument may lack completeness without encompassing knowledge on available help as well as information on actual help-seeking behaviour. The urgency to develop a comprehensive and updated instrument for understanding mental health help-seeking among adolescents is paramount, especially considering the transformation of help-seeking into a partially digitalized environment.

This project includes mixed methods, combining a qualitative participatory framework and quantitative longitudinal procedures. It consists of three work packages (WP), and stretches over a 3 year-period, focusing primarily on adolescents in secondary school. The first and third WP uses a participatory research approach, described previously in research by members of our research team (41). This approach includes both consultative and collaborative levels of participation in order to enhance involvement and empowerment of adolescents. To allow for a thorough investigation of social capital, mental health and help-seeking among adolescents, the involvement of adolescents to ensure relevance and improve the quality of research methodology is essential. Key stakeholders, such as representatives from municipalities, social services and schools, will be involved during the entire process to ensure relevance and applicability of research findings. The design and the scientific methods of this project have been developed through dialogues between researchers, health care professionals, representatives from municipalities and a national patient organization.

The schools are situated in three different districts in southwest Sweden, representing rural and urban settings. Sweden has a population of 10.5 million people (scb.se) and is considered a high-income country with a relatively low Gini Index, although rising rapidly (42). The healthcare system is publicly financed via local taxation and is structured into three levels; local, regional and national (43). Nurse-led school healthcare focuses primarily on preventive care and regular health check-ups, immunization etc. The school healthcare also offers counsellors and occasional visits from general physicians. The number of days per week that the school nurse and counsellor are present at each school can vary significantly, depending on the size of the school and local decision-making. Apart from that, healthcare services available to adolescents consist primarily of youth clinics and primary care. However, this system has been characterized as fragmented (9, 44).

This WP will address the first research question, i.e., How can social capital and help-seeking among adolescents in Sweden be assessed with high validity and reliability in relation to mental health? The WP is designed to tackle the absence of validated instruments that comprehensively encapsulate the concepts of both social capital and help-seeking as articulated by adolescents. Its objective is to create two distinct instruments catering to these specific aspects. It is of importance to establish instruments that cover both relevant contexts and provide an image of both the structure of networks and the perceived resources within them. The procedure follows a standardized methodology for developing and validating instruments within social and behavioural health research, put forward by Boateng et al. (45). The methodology provides a step-by-step guide accompanied by explanations of common pitfalls and successful practices. Combined with the participatory approach of the study, this ensures active collaboration with adolescents in (1) item development, (2) instrument development, and (3) evaluation of the instruments (45). The WP extends previous research undertaken by the research team, where a systematic review and evaluation of existing instruments shows a lack of adolescent involvement during development (26) and qualitative field work involving adolescents, which elucidates the importance of safe spaces, connectedness and predictability in adolescents’ social networks (28), and will now also involve adolescents from a suburban/city setting.

The main research question addressed in this work package is: What is the role of social capital for mental health and help-seeking in adolescence? The second WP is a longitudinal population study (53) of adolescents in the school-setting, designed to establish a baseline and a first-year follow-up to investigate how social capital is linked to help-seeking in adolescence and how social capital may facilitate early identification of adolescents at risk of developing severe mental health problems in need of treatment and support. It is well known that the prevalence of mental health problems increases during early adolescence (54), however, social capital tends to be more stable during these years apart from a transformation in the structure of social networks, which is mostly related to the expansion of peer networks (55). Therefore, we propose a one-year follow-up will provide valuable information into the changes of, and relationship between, mental health, social capital and help-seeking.

The main research question addressed in the co-production WP is: How can the knowledge generated throughout the project be translated into practice? This WP runs parallel with WP 1 and 2. It’s designed to evolve the generated knowledge and maximize its’ applicability during, rather than after, the project is finalized, thus, a process-oriented method will be applied. We do not wish to produce an academic product or program that is “dropped” on various bodies, such as schools or the student-health workers, but rather integrate potential users’ and stakeholders’ perspectives and knowledge to create something that will be viable, sustainable and useful from their perspectives. The idea of the participatory research process is to work towards a common goal, which is to improve early identification of adolescents at risk of developing severe mental health problems.

The project has received ethical approval from the Swedish Ethical Review Agency (Ref nr: 2023-01531-01). The studies will adhere to the principles of research ethics according to The Declaration of Helsinki (46), underscoring the importance of informed consent and voluntariness. All participants will receive oral and written information about the study aims and procedures and will be required to provide their written informed consent to participate prior to participation.

This project addresses the concerning public health challenge of increased mental health problems among adolescents and the paradoxical development of healthcare utilization and help-seeking (9–11). Converging evidence highlights the critical role of the social environment in influencing adolescent mental health (63). Therefore, there is great potential in exploring further the relationship between social capital and mental health, considering and building on previous research (12, 16, 23, 64). This project adds the scope of help-seeking, for improvement of preventive and promotive mental health work.

A limitation lies in the recruitment of schools willing to participate in the project. The approach as it is designed, may be perceived as burdensome by schools that face challenges with for example staffing, absenteeism, student violence, and poor student-teacher relationships. This may affect the representativeness of the school sample but is a natural consequence of voluntariness in research. The previously established contacts with municipal stakeholders involve schools from different socioeconomic settings, which will help compensate for this limitation. A strength of this project is the participatory approach, which values the knowledge and experiences of the target group and relevant stakeholders to help bridge the gap between research and practice. There are always challenges related to participation when involving young people in research (66). These relate to attaining a level of participation that encompasses authentic opportunities for participants to exert influence and structuring this engagement in a manner that fosters their comprehension of the nature and rationale behind their involvement. The key to overcoming this challenge lies in facilitating sustained participation throughout the project, allowing adolescents to gain confidence in the researchers and help improve their decision-making capabilities (41). One possible limitation is the finite transferability of the instruments developed in this project. It concerns validity over different social cultures and contexts, regions, or countries, affected by societal structures and resources. Similarly, future technical advancements relating to help-seeking may infer temporal sensitivity in unanticipated ways. Nonetheless, there will invariably be challenges relating to sustainability in the development of instruments aimed at capturing social phenomena. Another aspect of transferability concerns representativeness of the sample. Researchers should evidently be aware of the setting that their research is being conducted in, and what groups are represented in the sample. In our case, characteristics of participating schools, diversity of pupils etc., are considered carefully since these features will guide inferences and implications of the results. Lastly, we want to point out that the focus of this project is not on a particular vulnerable group, such as adolescents diagnosed with mental illness, but on adolescents in general within the societal context where this project takes place. We are, however, aware of the possibility of encountering vulnerable individuals during the project and will use the experience within the research team to guide individuals to appropriate care.