Glasgow scientists have identified a particular skin reaction in young people with a history of selfpharmacy

A University of Glasgow study published in Nature Mental Health has found: the skin of these teenagers reacts differently to stress than those who have never engaged in selfpharm.

Selfharm is a huge and growing problem. It is estimated that up to one in six teens have intentionally self-harmed at least once in their lives. It's considered one of the strongest predictors of suicide risk. But until recently, scientists understood little about the biological processes involved in this behaviour.

Professor Rory O'Connor's team decided to study the body's response. They measured electrodermal activity (EDA) - how the skin conducts electricity. When calm, conductivity is lower, and when stressed or fearful, it is higher. This has long been used as an indicator of emotional stress.

The study involved young people aged 16-25. They were divided into three groups:

• those who had never engaged in self-harm,
• those who had thought about self-harm,
• and those who had already practised self-harm.

The participants were given different tasks - repetitive sounds, a stressful task and emotional images - and the scientists measured skin reactions in parallel.

The result was alarming: those who actually engaged in selfpharm had stronger skin reactions even to neutral stimuli, let alone stressful ones. In other words, it was as if their bodies were living in a "constant alert" mode, where the emotional system was triggered faster than others. Under these conditions, any additional stress can be the last straw - and selfpharm becomes a way to quickly reduce internal pressure.

The researchers believe this discovery helps to understand why some young people limit themselves to thinking about selfpharm, while others move into action. The particular skin reaction may serve as a biological marker of increased vulnerability.

Scientists emphasise that selfpharm is the result of a combination of many factors: social, psychological, cultural and biological. But knowledge of such markers will help to identify those who are particularly at risk earlier and offer timely assistance, including emotion and stress management programmes.