BackgroundUnderstanding the association between sport-related concussions and the risk of suicidal and non-suicidal self-injury thoughts and behaviors (SITBs), including non-suicidal self-injury (NSSI), suicidal ideation (SI), suicidal plan (SP), and suicidal attempt (SA), is crucial for suicide prevention. We aimed to identify the circumstances in which individuals with or without a concussion are vulnerable to SITBs. MethodsThe cross-sectional study included 85,469 students from 63 Chinese university with a mean age of 19.6 years. Firstly, propensity score matching, and inverse probability of treatment weighting (IPTW) were used to match the concussion and non-concussion group based on a range of biological, social, and psychological factors. Subsequently, multivariable logistic regression and a decision tree algorithm were employed to evaluate the interaction and cumulative impact of these risk factors and concussion on the probability of SITBs. ResultsIn the unmatched sample, concussion exposures were associated with all SITBs, with NSSI (OR, 1.41), SI (OR, 1.10), SP (OR, 1.23), and SA (OR, 1.28). However, the matched and weighted sample only had a significant association with NSSI and SI. The decision tree model revealed that, in the unmatched sample, among individuals without depressive symptoms or childhood emotional abuse, the risk of concussion on SITBs increased from 45.5 % to 65.2 % (χ2, 9.370; adjusted P = .002) after experiencing sexual abuse and verbal bullying. In the matched sample, the risk increased from 46.2 % to 64.6 % (χ2, 6.848; adjusted P = .009). ConclusionOur study revealed that individuals who suffered concussions exhibited a significantly higher risk of SITBs.