There was a Chinese study that suggested that the COVID-19 pandemic has a significant influence on the PH of children and adolescents  . This study, still in the COVID-19 phase, showed the PSH prevalence of 25.8%, which as predicted was significantly higher than the before. Our survey results show that left-behind children, boarding students and adolescents with NSSI are more likely to be in the PSH state. Further findings highlight that childhood trauma and IA increased the risk of PSH by 1.95 and 5.20 times. And SEM also verified the initial hypothesis that childhood trauma directly or indirectly has a positive predictive effect on PSH through IA. In other words, IA plays a partial mediating effect in the relationship between childhood trauma and PSH.
Left-behind children refer to children aged 0 to 18 who cannot live with their parents and can only remain in the place of residence, because one or both parents have moved to other places for various reasons . Compared with ordinary children, left-behind children are more introverted, withdrawn and quiet, do not readily show their inner thoughts and feelings, are more indifferent and depressed, have an indifferent attitude towards things, and show less interest and concern for things  . These children are prone to a series of psychological and behavioral problems [35-37]. Our study also found that left-behind children were more likely to be in the state of PSH than children with parents around them. A previous study in China has shown that the prevalence of widespread psychological problems of junior middle school students in boarding schools was higher than that in non-boarding schools  . A survey of American Indian adolescent boarders showed significantly higher suicide rates among boarders than non-boarders  . According to the investigation, boarding schools do not pay enough attention to PH work. The reason may be that a whole set of the operating systems for PH education has not been formed, the allocation of teachers for PH education is not enough, and the development of PH education is not perfect, so it is necessary to strengthen PH education in boarding schools.
NSSI refers to intentional self-destruction of body tissue for purposes not approved by society, including cutting, burning, biting and scratching the skin, without suicidal intention . The worldwide prevalence of adolescent NSSI is about 17.2% , compared with 23.2% in China . The prevalence of NSSI was 35.6%in this study, which was significantly higher than previous studies. Some researchers have shown a relationship between NSSI and PSH. This study also inversely verified that NSSI behavior was a predictor and risk factor of adolescent PSH. Parents or schools are called on to speculate on the more hidden PH problems of adolescents, through abnormal behaviors that are easy to be detected, and to provide psychological assistance to avoid worse things from happening.
We investigated the participants' childhood trauma, which refers to a chronic form of parental abuse and, or neglect, different from the acute trauma that may occur in childhood related to post-traumatic stress disorder (PTSD, e.g., traumatic accident, single attack, etc.) . Numerous studies have shown that emotional, physical and sexual abuse are associated with high rates of PH problems. The results of the study showed that the majority (57.5%) of participants had at least one type of childhood trauma, which significantly increases the risk of PSH in adolescents. This is consistent with previous studies. Many previous studies have shown that gene expression, abnormal epigenetic changes, abnormal brain structure and function, and dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis may be the essential biological basis for the relationship between childhood trauma and physical and PH problems in later life [44, 45]. Recently, the study of inflammatory factors has also received great attention. Related studies have found that abnormal levels of inflammatory cytokines (TNF-α, IL-6 and acute C-reactive protein) and telomere length may be critical biological indicators of physical and psychological health problems in individuals with childhood trauma [46-49]. From a long-term point of view, childhood trauma not only increases the incidence of PSH in adolescents, but more seriously, many (but not all) childhood traumas are also associated with many types of mental disorders in the course of life, mainly primary mental disorders. They will continue into adulthood .
In this study, IA was used as an innovative point to explore the relationship between childhood trauma and adolescents’ PSH state. IA is the excessive and morbid use of the Internet, which will not only lead to a decline in performance, but also lead to a decline in depression, anxiety and PH problems. Especially, with the emergence and increase of online courses, adolescents have more access to the Internet and spend more time on it because of online home-based courses, which may also be one of the reasons for the increase in the prevalence of IA among adolescents. This is also a concern for many parents. In psychiatric clinics, many parents come to consult because their children are addicted to the Internet. In this study, we conducted an IA survey on the participants and found that one in five participants had IA, which greatly increased the risk of PSH. In addition, SEM confirms that childhood trauma has a direct effect on PSH and can also lead to PSH indirectly by IA. Due to IA, sufficient time spent on other personal and social activities will be reduced, including less time spent with friends or family. The problem may develop into more PH problems such as loneliness and depression [51, 52]. However, many longitudinal studies have shown a two-way relationship between IA and PH in adolescents, and either can be a cause or a result of the other. Creating a vicious circle. This study was cross-sectional, making it difficult to determine causality, so the longitudinal survey calculating the incidence rate has more excellent academic value . Many studies have confirmed that childhood trauma is associated with substance addiction and gambling. However, there are few studies on its relationship with IA. In a Turkish study on the risk and severity of IA in college students, emotional abuse appeared to be a major predictor of increased risk of IA among childhood trauma types . Physical abuse has been considered a possible risk factor for IA in Chinese students . The above reminds us that it is also important to assess other types of traumas in adolescents when considering IA.
This study is the first to try to explore the mediating effect of IA between childhood trauma and PSH. But the current research results are also limited by methodological factors. First, the study used a cross-sectional design, so the causal relationship is uncertain. To determine the causal relationship, a prospective study on the sequential assessment of IA and PSH will be meaningful. Secondly, our study sample only included adolescents from two cities in Anhui province, so the results may not be well generalizable to the whole of China or other countries. Thirdly, although the sample size was 866, it was not large enough. Finally, given that all variables are assessed subjectively, participants may exaggerate or weaken impressions and assessments of exposure to childhood trauma.