(MENAFN- The Conversation) Most of us know what it's like to be a teenager at school – and how it feels to fit into (or fall outside of) a school's social hierarchy. This typically includes some version of the popular kids, the loners and the in-betweeners, who have friendships that span across different groups.

However, teen hierarchies are more than a passing social order. Research suggests that these social networks and positions can shape mental health too. In a recently published study, my colleagues and I found that they also relate to one of the most serious health challenges among young people today: self-harm.

Self-harm – hurting yourself on purpose – is common in adolescence. While it is likely that some self-harm goes unreported, around 16%-22% of adolescents report having harmed themselves at least once. The behaviour appears to be increasing, particularly among adolescent girls. Worryingly, adolescents who self-harm have an increased risk of worsening health and mental health, including fatal outcomes like suicide.

There may be many reasons someone engages in self-harm. For example, it can be a coping mechanism to relieve emotional distress (intra-personal) by focusing on a physical sensation. Or it can be shaped by social factors (inter-personal) such as peer relationships.

For example, teenagers may be being influenced by the behaviour of others or use it as a means of communicating distress. Indeed, research has found that peer relationships are deeply important in adolescence and matter for self-harm.

However, little research has focused on how the school-based friendship networks of teens relate to self-harm. We addressed this gap by analysing data on teen friendship networks and self-harm from a cohort study of adolescent mental health in the UK called the Resilience Ethnicity and Adolescent Mental Health (Reach) study, which follows a large a group of people over time.

Reach has collected data from around 4,000 adolescents from 12 mainstream secondary schools in inner-city south London. Pupils at the schools completed questionnaires on their mental health and social networks (among other measures) over time. To date, Reach is the largest and most recent cohort study of adolescent mental health among young people from diverse inner-city areas in the UK.

In this study, we focused on the first year of Reach data collection, when adolescents were aged 11 to 14 years old. Adolescents were asked to report if they had“ever tried to harm or hurt themselves”, with 14% reporting yes. They were also asked to name friends within their school year. This is the first time a cohort study in the UK has collected data on both school friendship networks and self-harm.

We used social network analysis to “map” out teens' friendship networks and to calculate several measures reflecting young people's social positions within their networks.

This included:“popularity” (how many people named you as a friend),“bridging” (being an in-betweener and connecting otherwise disconnected friendship groups) and social isolation (having zero or one friend only), among other measures. We also looked at how many of their friends had reported self-harm, and then explored if and how these different network measures related to self-harm.

Social networks and self-harm

We found that both who adolescents are friends with in school and how they are connected to their friends were linked in different ways with self-harm. Strikingly, nearly half of adolescents had at least one friend who reported self-harm. This was linked to adolescents being more likely to report engaging in self-harm themselves, which might suggest peer-influence.

Various social positions in teen networks were also linked to self-harm. Some positions were protective, meaning adolescents were less likely to self-harm, whereas other positions were risky, meaning they were more likely to self-harm. Risky positions included social isolation, but also to some extent popularity and bridging (in-betweener).

While popularity is often seen as a desirable social status, it could also bring with it social pressures which may indirectly lead to self-harm. Bridging may reflect adolescents who are“between” different friendship groups, which may be socially taxing and link to self-harm.

Protective positions included“sociality” (nominating lots of people as friends) and being part of a tight-knit friendship group with friends who are friends with each other. However, the strongest links were for social isolation and having friends who report self-harm.

We also tested if there were any differences by gender. We expected the effects to be stronger among girls compared with boys. However, we found little evidence of this – which suggests that social networks relate to self-harm the same across boys and girls from our diverse, inner-city London sample.

It is important to note that these findings come from data that was collected at a single point in time. This means our findings are associations, and we cannot imply causation, or establish which direction the associations might be in. For example, do social networks predict self-harm, or does self-harm predict social networks? This needs to be further studied.

Our study highlights that self-harm is an important health challenge to tackle in adolescence – and considering teens' social networks in school may be an important part of tackling that challenge. Specifically, self-harm is not something to be understood in isolation – but there may be social elements to the behaviour for some, and it may be shaped by teens' social networks.

It also suggests that if both connection (such as having friends who self-harm) and disconnection (social isolation) from peers are associated, then there is a need for more than one approach to self-harm prevention in schools. While it may be tempting to focus on those who are socially isolated, it is also important to consider friendship group dynamics, and how adolescent's self-harm may affect the wider peer-network.

Ultimately, peer relationships in adolescence deeply affect us and can continue to shape mental health for decades. The more we understand teen social networks, the better we can support young people's mental health.

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