Non-suicidal self-injury (NSSI) is the act of purposely harming one¿s own body tissue without the intent of suicide, and a risk factor for future suicide attempts. To answer the question asking how these patients can overcome the instinct to avoid pain, I recently performed a study, published on European Journal of Pain (Leone et al. 2021), to assess the function of the nociceptive afferent pathway in adolescent patients with NSSI (n=30), compared with a matched control group, and to register any suicide attempt, describe its prevalence and find a possible correlation between suicide and neurophysiological measures (quantitative sensory testing, laser evoked potentials, conditioned pain modulation). My results indicated that patients with NSSI had a reduced amplitude of the vertex component of laser evoked potentials and an abnormal conditioned pain modulation, and more importantly, the amplitude of the vertex component was associated with suicidal risk. The strong association of a reduced amplitude of the vertex component with suicide raise the possibility to use it as a non-invasive biomarker of suicide in self-harming adolescents. Admittedly, albeit extremely promising, my previous study presents several limitations that I've planned to address in this further study: 1) replication of data; 2) assessment of the nociceptive-specificity of the biomarker by using multimodal evoked potentials; 3) assessment of the effect of a lack of attentional drive, itself related to suicidality, on the vertex component. To do so I've planned to perform a neurophysiological study on a larger sample of adolescents with NSSI with and without a previous suicide attempt (n=50), in collaboration with the Adolescent Unit of the Child Psychiatry Department of Sapienza University, to assess somato-sensory evoked potentials, auditory evoked potentials and laser evoked potentials during a specific task to monitor attention.
In recent years, the increase in Western countries of self-injurious behaviours, especially during adolescence and young adulthood, has made NSSI a major public health issue (Klonsky, 2011). The Covid-19 pandemic further increased the incidence of suicidal behaviour in adolescence defining a social emergency (Melhem et al.2021).
Whether a large collection of psychological variables have been associated with suicide progression (Victor and Klonsky 2014), no information is available in regard to quantitative neurophysiological measures. A previous recent study by our group successfully identified a candidate neurophysiological biomarker among self-harming adolescents, raising the possibility to identify patients with higher risk of suicide progression. This further study aims at confirming the role of this neurophysiological biomarker and at defining how it directly reflects the mechanisms that give rise to the transition to suicide, potentially deepening our knowledge on the pathophysiology of suicide.
Significance: the importance of this project is twofold: 1) it would allow the introduction in clinical practice of a fast and non-invasive biomarker to select patients at higher risk of suicide among the NSSI population and 2) it will, hopefully, deepen our knowledge on the physiological background of suicide. Although, we have to take into account that a biomarker can demonstrate good utility because it is able to identify clinically meaningful groups of patients with a high sensitivity and specificity, however, this does not necessarily imply that the biomarker reflects directly the mechanisms that give rise to a given clinical condition, as the patterns of neural activation that allow discrimination between conditions might be entirely epiphenomenal.