Psychological inflexibility processes and nonsuicidal self‐injury: Concurrent and prospective associations

Objective The aim of this study was to examine concurrent and 3‐month prospective associations between a multidimensional measure of psychological inflexibility and nonsuicidal self‐injury (NSSI) among participants with a self‐harm history. Method Participants completed measures of NSSI, psychological inflexibility, negative urgency, and depression at baseline (N = 106, Mage = 34.70, SD = 9.43, 66% women), and were again assessed at follow‐up (N = 86). Results Participants currently engaging in NSSI reported significantly higher psychological inflexibility as compared to those who have ceased NSSI. After controlling for covariates, psychological inflexibility was concurrently associated with NSSI recency and longitudinally predicted perceived likelihood of future NSSI. Psychological inflexibility was not associated with new NSSI acts after including baseline covariates. Finally, psychological inflexibility subscales demonstrated differential relationships with various NSSI functions. Conclusion Results highlight the psychological inflexibility model's utility in understanding NSSI and have implications for future research that may inform clinical practice.