Although anger is theorised to play a key role in the manifestation of non-suicidal self-injury (NSSI), prospective research in real-world settings is limited. Therefore, the present study examines (1) whether individuals with and without a history of NSSI differ in anger levels in their natural setting and (2) whether heightened self- or other-directed anger predicts NSSI cognitions (i.e. thoughts and self-efficacy to resist NSSI) and behaviour in daily life. Using ecological momentary assessment in 60 emerging adults (ages 18-22) with and without past-year NSSI, participants completed eight daily surveys over 12 days, yielding 4,587 assessments (median compliance = 83.3%; IQR = 71.9-91.7). Emerging adults who used NSSI in the past year reported higher anger at self and others than peers without NSSI history, with higher-than-usual anger at self, but not at others, predicting greater NSSI thought intensity and lower self-efficacy to resist NSSI 90 minutes later. Anger at self also signaled increased risk for NSSI behaviour, but this association became non-significant when controlling for NSSI thoughts. These findings highlight differences in the object of anger between individuals with and without past-year NSSI and underscore the clinical importance of interventions focused on reducing self-directed anger to decrease NSSI thoughts and ultimately prevent self-injury.
Dierickx et al. (Mon,) studied this question.