In a groundbreaking study conducted at the University of Glasgow, researchers have delved deep into the complexities of emotional processing and electrodermal activity (EDA) among young individuals who engage in self-harm. This extensive investigation, published in Nature Mental Health in November 2025, leverages sophisticated physiological measurement techniques to discern subtle differences in autonomic nervous system activity across distinct self-harm profiles, offering fresh insights into the psychophysiological underpinnings of self-injurious behavior.
The research employed a quasi-experimental design to meticulously compare three clearly defined groups: those with no history of self-harm, individuals with self-harming ideation who have never enacted self-injury, and participants who had engaged in self-harm within the prior year. This stratification allowed the team to isolate markers that differentiate mere ideation from actual enaction of self-injury, providing crucial understanding of risk factors and emotional regulation differences within these populations.
Participants were rigorously screened through a multi-stage process involving online and telephonic assessments, ensuring precise group allocation based on self-reported lifetime and recent histories of self-harm ideation and behavior. The final sample comprised 62 controls, 51 individuals with self-harm ideation, and 67 who had enacted self-harm recently, providing a robust dataset for comparative analysis.
Electrodermal activity, an established index of sympathetic nervous system arousal, was captured continuously throughout the study using Ag/AgCl electrodes applied to the non-dominant hand. The BIOPAC MP160 system enabled high-fidelity recording of skin conductance levels (SCL) and non-specific skin conductance responses (NS-SCR), critical measures reflecting baseline emotional tone and phasic reactivity to stimuli respectively.
The research protocol unfolded across multiple experimental phases beginning with baseline familiarization to physiological recording equipment, followed by a tonal habituation task. In this task, participants were exposed to a sequence of 15 auditory tones designed to engender measurable skin conductance responses, evaluating how rapidly individuals habituate to neutral auditory stimuli. The habituation rate was meticulously quantified by pinpointing the last tone generating a skin conductance response before the onset of three consecutive non-responses, a metric sensitive to autonomic adaptation processes.
Following this habituation task, participants viewed a randomized series of emotional images taken from the International Affective Picture System (IAPS). These images spanned varied emotional valences and arousal levels, enabling assessment of differential autonomic reactivity to emotive content before and after the application of a psychosocial stress task. The emotional images phase provided an opportunity to probe the interaction between stress exposure and subsequent affective reactivity.
The psychosocial stress task employed was the Maastricht Acute Stress Test (MAST), a rigorous and validated protocol comprising repeated immersions of the participant’s hand into ice-cold water combined with socially evaluative mental arithmetic challenges. This task reliably activates the hypothalamic–pituitary–adrenal (HPA) axis and the autonomic nervous system, serving as an effective laboratory analog of acute stress. Skin conductance data were captured during three discrete epochs corresponding to the onset, midpoint, and conclusion of the stress task, allowing temporal mapping of stress-evoked physiological dynamics.
Importantly, the study also integrated comprehensive interviews to assess participants’ mental health history and nuances of self-harm behavior—including suicidal intent—using the widely validated Self-Injurious Thoughts and Behaviours Interview (SITBI). Such multidimensional assessment ensured the alignment of physiological data with clinical context, enhancing interpretive validity.
Technically, data underwent rigorous preprocessing steps tailored to the physiological signals’ statistical properties. Electrodermal activity data were subjected to square-root transformations to normalize distributions by reducing skewness and kurtosis, a critical enhancement ensuring reliable parametric statistical analyses. This transformation approach aligns with best practices in psychophysiological research, facilitating cross-study comparability.
Statistical modeling leveraged generalized linear models (GLM) to accommodate diverse data distributions and covariates like age and sex. For example, habituation to the auditory tones was analyzed using a Poisson log-linear model appropriate for count data. Meanwhile, assessments of skin conductance across phases of the stress task used multilevel linear GLMs to parse group differences and phase interactions, underscoring the study’s sophisticated analytical approach.
Preliminary findings indicated significant differences in baseline sympathetic activity and habituation patterns between the groups. Notably, individuals who had recently enacted self-harm exhibited distinct autonomic profiles including altered habituation rates and heightened skin conductance responses during stress, suggestive of dysregulated emotional and physiological stress processing.
Results from the emotional images phase highlighted challenges in eliciting consistent skin conductance responses, especially following the stress task where response rates dropped markedly. This limitation, acknowledged by the authors, underscores the complexity of measuring affective reactivity and suggests potential habituation or diminished responsiveness to repeated emotional stimuli in this population.
Despite these challenges, the study’s comprehensive multi-modal design and innovative methodological rigor provide compelling evidence that physiological markers like EDA can shed light on the mechanisms underlying self-harm behaviors. The nuanced physiological signatures observed may eventually inform tailored intervention strategies targeting autonomic dysregulation in vulnerable youth.
The researchers emphasized the challenges posed by recruitment amid pandemic-related disruptions but underscored the importance of their large, well-characterized sample for enhancing the generalizability of their findings. Additionally, ethical considerations, including rigorous risk assessments and participant safety measures, elevated the study’s clinical and scientific integrity.
This research exemplifies the intersection of cutting-edge psychophysiology and mental health science, laying essential groundwork for future studies exploring the bidirectional relationship between emotional processing abnormalities and behavioral manifestations such as self-harm. By rigorously mapping how the autonomic nervous system responds to stress and emotional stimuli in at-risk youth, new horizons open for personalized medicine approaches addressing emotional dysregulation.
As science continues to decode the complex tapestry of mental health disorders, studies like this resonate profoundly, spotlighting the crucial importance of integrating physiological, psychological, and clinical dimensions. The findings set a precedent for leveraging objective biomarkers in psychiatric research, ultimately catalyzing better diagnostics, prevention, and therapeutic innovations for young people grappling with self-harm.
For scientists, clinicians, and the broader public invested in mental health advances, the insights from this study offer a clarion call to deepen our understanding of the embodied nature of emotional suffering—ushering in a future where interventions can be precisely tailored to the physiological realities of those most in need.
Subject of Research: Emotion processing and electrodermal activity in young individuals who self-harm.
Article Title: Emotion processing and electrodermal activity in young people who self-harm.
Article References:
Wetherall, K., Cleare, S., Belkadi, N. et al. Emotion processing and electrodermal activity in young people who self-harm. Nat. Mental Health 3, 1374–1383 (2025). https://doi.org/10.1038/s44220-025-00520-5
Image Credits: AI Generated
DOI: November 2025
