The relationship between the prevalence and severity of Non-suicidal self-injury (NSSI) and personality traits among Chinese junior high school students

Background Non-suicidal self-injury (NSSI) is more common in adolescents and its occurrence may be influenced by personality traits. Children and adolescents are a high-risk group for NSSI. Although there are some studies on the prevalence of NSSI, however, there are fewer studies on the factors associated with the severity of NSSI and the specific causes of the influence of NSSI and personality traits. Methods Participants of this study were junior high school students enrolled in three different schools of a Chinese province. NSSI was evaluated using the Adolescents Self-Harm Scale and their personality traits were assessed using the Neuroticism Extraversion Openness Five-factor Inventory (NEO-FFI). Results 2376 junior high school students participated, and the annual incidence of NSSI was 37.1% (n=881). The mean age of the NSSI-detected individuals was 13.61 years (SD=1.017). Out of total number of detections, 56.6% (n=499) were female and 67.4% (n=594) were individuals who self-injured using multiple means. Hair pulling, scratching the skin, and whacking harder objects with the hand were the most common modes of NSSI, with incidences of 51.0%, 43.0%, and 42.8% respectively in the NSSI-detected population. There was a negative association between grade and NSSI severity (p < 0.05), and NSSI was more severe in females. The scores in the Neuroticism dimension were higher in the group with NSSI than in the group without NSSI, while the scores in the extraversion, openness, agreeableness and conscientiousness dimensions were lower than in the group without NSSI (p < 0.01). Neuroticism and openness were significantly positively correlated with NSSI severity, and extraversion, agreeableness, conscientiousness were significantly negatively correlated with NSSI severity (p < 0.01). Conclusion The severity of NSSI was relatively higher in lower grades among junior grades and females, and the number of self-injury using multiple means was significantly higher; hair pulling, skin scratching and whacking harder objects with hands were the most common NSSI modalities. Among the personality traits, for the incidence of NSSI, high neuroticism was a risk factor, and high extraversion, openness, agreeableness, and conscientiousness were protective factors. For the severity of NSSI, high neuroticism and high openness were risk factors, and high extraversion, high agreeableness, and high conscientiousness were protective factors.