Pressure pain threshold may help identify adolescents at high risk for self-harm

Pressure pain threshold may be a novel biomarker for identification of high risk for self-harm among adolescents, according to results of a cross-sectional study published in JAMA Network Open.

“Advances have been made using machine learning and functional imaging to identify adolescents who are suicidal, but there are few recognized biological, clinical or psychological risk factors that could be applied clinically with confidence,” Tatum M. Cummins, MSc, of the Institute of Psychiatry, Psychology and Neuroscience at King’s College London in the U.K., and colleagues wrote. “Contemporary theories of suicidal behavior posit that individuals who engage in suicidal behavior must develop an acquired capability to do so; a component of this is proposed to be an elevated pain tolerance. There is some evidence that individuals who self-harm have altered pain perception, but the causes remain obscure, and the impact of self-harm on nonpain somatosensory sensitivity is even less well-understood.”

To address this research gap, the researchers used quantitative sensory testing to evaluate somatosensory function among 64 children and adolescents aged 13 to 17 years (53% girls; 78% living in residential care; mean age, 16.34 years) with no underlying health conditions living in care grouped according to the number of self-harm episodes in the past year, as well as to compare these individuals’ somatosensory profiles with community control participants to assess associations with self-harm incidence or frequency. They recruited participants between January 2019 and March 2020 from local authority residential care settings in the U.K., as well as from schools and youth groups in the U.K., and used intellectual disability, autism spectrum disorder or recent serious injury as exclusion criteria. The researchers used a standardized quantitative sensory testing protocol to determine baseline somatosensory function. They calculated associations between somatosensory sensitivity, incidence and frequency of self-harm, residential status, age, gender and prescription medication They also evaluated potential associations between self-harm and specific types of tests, such as painful or nonpainful.

Results showed significant pain hyposensitivity among those with five or more self-harm incidences vs. community control participants after adjustment for age, gender and prescription drug use. After similar adjustment, the researchers noted hyposensitivity extended to nonpainful stimuli. They linked most of the observed variance to pressure pain threshold.

“How pain sensitivity changes with age and whether these sensory changes remit with changing incidence or cessation of self-harm over time is unknown,” Cummins and colleagues wrote. “Future studies should explore whether a test of pain sensitivity can predict the onset of self-harm and completed suicides. Furthermore, these findings could be extended to longitudinal research in adults who currently or previously had self-harmed to examine whether sensory hyposensitivity in adolescents is lost and how sensory sensitivity manifests in adulthood.”