Different self-damaging behaviours, similar motives? Testing measurement invariance of motives for nonsuicidal self-injury, disordered eating and substance misuse

Objectives: Theory and research suggest that distinct self-damaging behaviours (SDBs; e.g., nonsuicidal self-injury [NSSI], restrictive eating, binge eating, drug misuse, alcohol misuse) share similar motives. However, few studies have used a common self-report inventory to investigate the shared relevance and relative salience of motives for SDBs. Accordingly, the present study: (1) examined whether self-report scales assessing intrapersonal motives (i.e., relieving negative emotions, enhancing positive emotions, punishing oneself) and interpersonal motives (i.e., bonding with others, conforming with others, communicating distress, communicating strength, reducing demands) have invariant factor structures across SDBs; and (2) compared the salience of these motives across SDBs. Methods: 1018 adults (54.6% men, M_age = 35.41 years) with a history of SDBs were allocated to the following groups: NSSI (n = 213), restrictive eating (n = 200), binge eating (n = 200), drug misuse (n = 200) or alcohol misuse (n = 205). Participants reported on their motives for engaging in their allocated SDB. Measurement invariance analyses compared the factor structures and latent means of the motive scales across SDBs. Results: The motive scales had comparable factor structures across SDBs. Intrapersonal motives were most strongly endorsed for NSSI and drug misuse. Interpersonal motives were most strongly endorsed for drug and alcohol misuse. All motives were least salient to restrictive eating. Conclusions: Results suggest that common motives underlie distinct SDBs and that they can be adequately assessed using a single self-report inventory. However, certain motives are more relevant to some SDBs than others, with restrictive eating being the most motivationally distinct SDB. This knowledge can inform transdiagnostic models and interventions for SDBs.