New study uncovers a key biological marker into why young people self-harm
Published: 27 November 2025
As many as one in six teenagers have self-harmed at some point in their lives. As well as being an indicator of emotional pain, self-harm is also the best-known predictor of death by suicide – yet researchers know little about the emotional and biological factors that lead to it.
As many as one in six teenagers have self-harmed at some point in their lives. As well as being an indicator of emotional pain, self-harm is also the best-known predictor of death by suicide – yet researchers know little about the emotional and biological factors that lead to it.
A new study published in Nature Mental Health, led by Professor Rory O’Connor from the University of Glasgow and funded by the Medical Research Foundation, helps to uncover the biological mechanisms behind why young people self-harm.
Expanding on his research into the psychological factors associated with self-harm, Professor O’Connor’s latest findings reveal that young people with a history of self-harm present a particular biological skin response to electrical activity – a physiological marker associated with difficulties in generating and managing emotions.
Self-harm, defined as intentional self-poisoning or self-injury, is a significant public health issue. While statistics are never entirely accurate because of the stigma and shame that surrounds it, the NHS Adult Psychiatric Morbidity Survey 2023/4 estimates that rates of self-harm in the UK have increased, from 2.4% of 16- to 74-year-olds in 2000, to 10.3% in 2023/4. The figures are even higher among 16- to 24-year-olds, where 31.7% of women and 15.4% of men reported having self-harmed at least once.
The survey also reveals that most people who had self-harmed reported doing so to relieve unpleasant feelings of anger, tension, anxiety, or depression.
For many young people, self-harm is used to deal with distress or overwhelming feelings. It is this emotion regulation mechanism that Professor O’Connor is focused on investigating.
Professor Rory O’Connor, Chair in Health Psychology at the University’s Institute of Health and Wellbeing, said: “The factors associated with self-harm are complex; indeed, self-harm has cultural, social, psychological and biological influences. However, the biological mechanisms underpinning self-harm are poorly understood.”
Evidence suggests that the brain systems involved in generating emotions (emotion arousal) are linked to those involved with managing them (emotion regulation).
Specifically, the limbic system made up of nerves and networks in the brain is key to emotional processing, mood regulation, and the creation of emotional memories. Certain parts of the limbic system, such as the amygdala, may also be particularly vital for processing fear and heightened emotions.
Studying the bio-physiological mechanisms associated with generating emotions could be key to understanding why young people self-harm, helping to improve treatments for those at risk.
With funding from the Medical Research Foundation, Professor O’Connor has been investigating how emotion arousal is associated with self-harm in young people by observing a biological factor called ‘electrodermal activity’ (EDA).
EDA refers to changes in the skin’s ability to conduct electricity. When a person is calm, their skin’s electrical resistance is typically higher; during states of excitement, stress, or fear, it tends to decrease, largely due to sweat glands and the sympathetic nervous system. EDA has been closely linked to automated emotional and cognitive processing and is often used in research to investigate emotional responses.
In this new experimental study, the team measured EDA among three groups of young people aged 16-25 years with varying histories of self-harm; those with no history, those with self-harm ideation but no enaction, and those who had enacted self-harm.
Dr Karen Wetherall, Research Fellow at the University of Glasgow and first author of the study, added: “Distinguishing what makes a young person vulnerable to acting on their self-harm thoughts is crucial to understanding why some people transition from thinking about self-harm, to enacting it. Previous research findings have been unclear about how EDA and self-harm may be related - so we wanted to shed more light on this relationship.”
The team measured EDA during several tasks, including repeated auditory tones, a stress-induction experiment, and an emotional images task.
Researchers discovered that young people who engaged in self-harm showed stronger physical reactions (measured by EDA) when faced with both neutral and stressful tasks. This suggests that young people with a history of self-harm may experience emotion arousal differently, making it harder to regulate their emotions.
Professor O’Connor added: “Our findings suggest that the way young people process emotions may be key to understanding self-harm. The results also indicate that tailored interventions focusing on emotion regulation strategies could be particularly effective in managing self-harm”.
Clinically speaking, these insights may help identify which young people are most at risk of self-harm or suicide. The study also lays the groundwork for future research into treatments, with the potential to improve outcomes for young people struggling with their mental health.
Enquiries: ali.howard@glasgow.ac.uk or elizabeth.mcmeekin@glasgow.ac.uk
First published: 27 November 2025