title: The role of endogenous opioids in non-suicidal self-injurious behavior: methodological challenges.
abstract: Relief from emotional pain is a frequently cited reason for engaging in non-suicidal self-injury. The exact mechanism by which self-injury brings about this relief is unknown, but the potential role of endogenous opioids in affective regulation has been posited. Few studies have investigated this and there are a number of methodological challenges to measuring endogenous opioid activity in this population. Furthermore as the majority of research to date has focused on inpatients with borderline personality disorder (BPD), it is uncertain if the findings of previous studies would also apply to those who self-injure but who do not have BPD. Whether or not altered endogenous opioid levels are a cause or a consequence of self-injury is unknown and to this end, comparing self-injury ideators with enactors, may offer a window of insight. Another candidate system, the endocannabinoid system, should also be explored in relation to this research question. The current commentary aims to tease apart the methodological issues in this area of research and stimulate further discussion of this topic.
authors.affiliation: University of Glasgow, Suicidal Behaviour Research Laboratory, Institute of Health and Wellbeing, College of Medical, Veterinary and Life Sciences, University of Glasgow, Gartnavel Royal Hospital, 1055 Great Western Road, Glasgow G120XH, United Kingdom. Electronic address: o.kirtley.1@research.gla.ac.uk.
authors.forename: Olivia J
authors.initials: OJ
authors.lastname: Kirtley
authors.affiliation: University of Stirling, Division of Psychology, School of Natural Sciences, Stirling FK9 4LA, United Kingdom.
authors.forename: Ronan E
authors.initials: RE
authors.lastname: O'Carroll
authors.affiliation: University of Glasgow, Suicidal Behaviour Research Laboratory, Institute of Health and Wellbeing, College of Medical, Veterinary and Life Sciences, University of Glasgow, Gartnavel Royal Hospital, 1055 Great Western Road, Glasgow G120XH, United Kingdom.
authors.forename: Rory C
authors.initials: RC
authors.lastname: O'Connor
mesh_terms: D001883:Borderline Personality Disorder / Q000000981:diagnostic imaging / Q000503:physiopathology; D001921:Brain / Q000000981:diagnostic imaging / Q000503:physiopathology; D019963:Clinical Chemistry Tests / Q000379:methods; D063388:Endocannabinoids / Q000378:metabolism; D006801:Humans; D059906:Neuroimaging / Q000379:methods; D018847:Opioid Peptides / Q000378:metabolism*; D010146:Pain / Q000503:physiopathology; D011877:Radionuclide Imaging; D016728:Self-Injurious Behavior / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000523:psychology; D013850:Thinking / Q000502:physiology
chemical_list: D063388:Endocannabinoids; D018847:Opioid Peptides
keywords: Cannabinoids; Ideation; Methodology; NSSI; Opioids; Self-harm; Self-injury