Non-suicidal self-injury (NSSI) refers to a series of direct, deliberate and repeated actions that do not commit suicide but do not lead to death, such as cutting, stabbing, bumping, scratching, etc.[1, 2]. NSSI can run through all ages and is more common in adolescents and early young adults. Studies have shown that the lifetime prevalence of adolescents in the world is 5.5%-22.1%[3–5]. For adolescents with mental disorders, the prevalence is even higher, with the prevalence of one-time NSSI reaching 60% and the prevalence of repeated NSSI reaching 50%[6]. In China, studies have reported that the incidence of NSSI among middle school students is 27.4%, among which the highest incidence is 15.9% among adolescents aged 13–17[7]. NSSI not only causes physical impairment, affects emotional functioning, interpersonal relationships and work and school performance, but also increases the risk of suicide. Suicide deaths in adolescents and early adulthood were strongly associated with NSSI experience[8]. Adolescents with a history of NSSI are about three times more likely to commit suicide in the future than the general population [9]. NSSI is an important risk factor for suicide [10, 11], the risk of suicidal behavior also increased with the increasing frequency of NSSI. Therefore, NSSI in adolescents has become a social public health problem that cannot be ignored.
With the deepening of research on NSSI, more and more evidence shows that NSSI is an addictive behavior in adolescents [12]. In recent years, studies on NSSI in adolescents suggest that NSSI is closely related to neural reward circuits. Compared with adolescents without NSSI, adolescents with NSSI showed increased activity in the striatal reaction-related brain areas [13]. The self-report of addiction experience of self-injurers showed that self-injurers knew the harm but still repeated it, had a sense of craving for self-injurious behavior, and their emotions were released after self-injurious behavior, and there was tolerance to self-injurious behavior. In addition, studies have shown that NSSI patients have changes in endogenous opioid peptides, and the levels of endorphins and dopamine in the brain increase after NSSI [14], while the endogenous opioid system is involved in regulating addictive behaviors, suggesting that NSSI in adolescents has certain addictive properties.
Do adolescents with NSSI have other addictive behaviors based on the addictive attributes, such as psychoactive substance addiction, Internet addiction, etc.? At present, there are more and more studies on Internet use and adolescents' NSSI [15, 16].Previous studies have shown a certain correlation between social media addiction and adolescents' NSSI. However, most of the current researches on social media are based on computer terminals [17, 18]. With the development of mobile Internet, the popularity of smart phones and the increase of mobile phone social applications, the use of mobile phone social media is becoming more and more widespread, and people's use and dependence on mobile phone social media is constantly increasing [19–21]. At present, there are many studies on mobile phone dependence and computer social media dependence, while there are few studies on mobile phone social media dependence. Compared with traditional social media, mobile phone social media has stronger immediacy, portability and interactivity, which increase use frequency of mobile social media, and also indicate the correlation between mobile phone dependence or computer terminal social media dependence and NSSI cannot simply be applied to mobile phone social media dependence.
Mobile phone social media dependence [22] refers to the use of specific social media on mobile phones, such as Tiktok, wechat, Weibo, QQ, etc., which is addicted, over-invested and difficult to control. With the increasing abundance of smartphone applications, teenagers spend more and more time using mobile social media every day, which also makes the phenomenon of dependence on mobile social media more and more common [23]. Excessive addiction to mobile social media, long-term exposure to mobile social media platforms, more opportunities to contact information about NSSI, more time exposure to network environment of communication and talk about self-injury.Then whether mobile phone social media dependence will increase the occurrence of non-suicidal self-injury in adolescents? whether there are more dependence on mobile phone social media among adolescents with NSSI? Is there a correlation between mobile phone social media and NSSI? This study attempts to explore the correlation between NSSI and mobile phone social media dependence in adolescents.