China’s economy has rapidly developed since it instituted economy reform and the Opening-Up Policy (1978). Although people’s living standards have improved, the economic gap between rural and urban areas has expanded since 1990. Many people moved from rural to urban areas to seek employment, but significant numbers of rural children did not accompany or follow their parents to the city; these children are known as left-behind children (LBC)[1]. According to The Ministry of Civil Affairs of China, there were 6.97 million LBC in rural areas at the end of 2018 [2], and this number increased to 11.99 million by the end of 2021 [3]. A meta-analysis of 89 studies and 106,167 LBC cases showed that many of the children had serious behavioral, psychological, and physical health problems [4]. Previous studies of LBC’s physical health problems have focused on wasting [5], anemia [6], and stunted growth [7] in this population. Their reported 2016 rates for stunting, underweight, wasting, and anemia were 12.1%, 4.0%, 1.5%, and 43.8%, respectively. While these rates have decreased compared with the 2013 investigation, indicating a lowered risk, they are still considered to be high [8]. Another study reported that the weighted prevalence of anemia and stunting among LBC was 26.5% and 16.6%, respectively, and emphasized the household food insecurity associated with both conditions [9]. Furthermore, studies have shown that LBC are more likely to have poor lifestyles, including internet addiction [10], smoking [11], excessive drinking [12], and skipping breakfast[13], compared with non-left-behind-children (NLBC). LBC are also at risk of suffering from various psychological problems[14–16], including depression[17], anxiety[18], and suicidal ideation [19]. Indeed, much research has confirmed that, overall, LBC face more severe psychological problems than NLBC [20]. For example, one study showed that the incidence of serious psychological problems among LBC was approximately 2.7 times higher than that among NLBC, which may be attributable to the interaction effects of multiple factors such as family, school environment, gender, and personality [21]. In general, depression and anxiety are the most commonly observed psychological problems among children and adolescents, and are especially prevalent among LBC [22], as indicated by another cross-sectional study, which reported rates of depression and anxiety disorders among LBC as 14.1% and 25.1%, respectively [23]. Further research reported that LBC were more likely to experience depression symptoms (DS) and anxiety symptoms (AS) compared with other psychological problems, owing to their special family environment and separation experience [24]. Additionally, a systematic review confirmed that LBC were at higher risk of experiencing anxiety (risk ratio [RR] = 1.52) and depression (RR = 1.85) than substance abuse (RR = 1.24)[4]. Another study found that 15.9% and 17.8% of their LBC participants reported having passive and active suicidal ideation, respectively, with depression [25] .
Children and adolescents are increasingly suffering from negative psychological symptoms [26]. According to World Health Organization data, one in seven children and adolescents aged 10 to 19 worldwide suffer from psychological problems [27], and symptoms are especially severe in special groups such as migrant children [28], refugee children [29], and LBC [30]. Indeed, a study conducted in the United States, indicated that the prevalence of post-traumatic stress disorder (PTSD) and depression in migrant adolescents was 33.3% and 20%, respectively [31], and a study from Germany reported that 76% of refugee children and adolescents were diagnosed with PTSD [32]. Similarly, a high prevalence of psychological problems has been observed in developing countries [33]. For instance, In Vietnam, the rate of abnormal emotional symptoms among LBC was reportedly 17.3% [34], and a high prevalence rate was also observed among LBC children and adolescents in China [35]. One cross-sectional study found, moreover, that the prevalence of overall mental health problems among LBC (37.4%) was higher than that for migrant adolescents (27.9%) and local adolescents (27.1%)[36]. Furthermore, another study showed that, compared with NLBC, LBC had a 52%, 85%, and 70% higher risk of depression, anxiety, and suicidal ideation, respectively, which undermined their health and body development [37].
It is an indisputable fact that psychological problems have adverse effects on human health. Furthermore, long-term psychological problems have a negative impact on physiological function [38]. A 7-year longitudinal study confirmed that depression can lead to emotional eating behavior, which may increase the risk of nutrition diseases [39]. It also confirmed that major DS and AS are related to some chronic diseases, such as tumors, functional dyspepsia, and chronic viral hepatitis [40]. There is also a strong correlation between suicidal ideation and self-harm behaviors among people suffering from long-term psychological problems [41]. Severe DS in children and adolescents, along with suicidal ideation owing to feeling hopeless, and intense emotional distress [42], Moreover, other studies have shown that individuals who suffer with long-term negative emotions and suicidal ideation are at increased risk of self-harm behavior, and may even commit suicide [43]. Therefore, because psychological symptoms seriously compromise the health of LBC, it is crucial to pay attention to their mental health issues and provide timely interventions.
Many studies have reported that LBC’s psychological health issues are associated with individuals’ unhealthy lifestyles [24]. One study found, for example, that LBC who habitually skipped breakfast, who had prolonged screen time exposure, and whose sleep patterns were regularly disrupted were more likely to evidence AS [44]. Another study showed that LBC diagnosed with internet addiction were 2.78 times more likely to experience depression compared with rural children without internet addiction [45]. Additionally, a study focused on LBC’s health behavior and health status reported detection rates of 8.4% for internet addiction, 17.1% for tobacco use, and 33.6% for alcohol consumption. Importantly, these high rates of unhealthy behaviors are often accompanied by a high prevalence (6.4%) of suicide ideation [46]. LBC are reportedly also at high risk for psychological problems in school owing to being bullied [47], to discrimination [48], and to sexual assault [49]. Indeed, a longitudinal study confirmed that being bullied was positively associated with depression among LBC, with negative thoughts and low self-compassion acting as mediating factors that increased the risk of depression [50]. Extensive academic research indicates that, crucially, most LBC perceive discrimination, which increases their risk of strong suicide ideation [51]. According to another report [49], LBC are also at higher risk of sexual abuse owing to insufficient surveillance by their parents; the prevalence of depression caused by sexual abuse has been reported as 22.8% among Chinese teenagers [52]. Although the study is not focused on LBC, it is reasonable to infer that LBC may be more susceptible to sexual abuse-provoked depression[49, 51, 52]. Additionally, family factors can affect LBC’s psychological symptoms, including family income [53] parental education [54], and rearing patterns [55]. For example, A research showed that a low family income level was positively associated with severe DS among LBC, specifically, family income below 2,000 RMB per month presented a risk of major DS that was 4.02 times greater than that in homes with a monthly income above 8,000 RMB [56]. Another study from South China indicated that parental educational level influences LBC’s psychological health: lower levels are associated with the worst psychological health among LBC, and, in particular, a mother’s low educational level (e.g., high school) predicts serious behavioral problems and hyperactivity-inattention issues in their LBC [57] Several studies, moreover, have suggested that different rearing patterns are related to LBC‘s psychological health [58, 59]. One study focused on the relationship between rearing style and emotional and behavioral problems (EBP) among LBC and found that a positive rearing style reduced the risk of EBP by prompting children’s self-control, whereas, a negative rearing style directly increased the risk of EBP [58]. Another study further showed that authoritarian and permissive/neglectful parenting styles have a significantly negative influence on cognitive emotion regulation [59]. While many studies have analyzed the association between family characteristics and LBC’s psychological symptoms, fewer studies have examined the relationships between LBC’s psychological symptoms and left-behind characteristics (e.g., parent-child separation time, duration of parent-child separation, and type of caregiver).
In summary, the literature indicates that LBC suffer from severe psychological health issues—especially DS and AS—caused by various factors, which compromise their physiological function and mental health [41]. Therefore, psychological health problems and their risk factors among LBC urgently require close attention. Furthermore, most research has determined that individual lifestyle, school social environment, and family factors are strongly associated with DS and AS among LBC [53, 54], but only a few studies have examined the relationship between left-behind characteristics and DS and AS among LBC [60, 61]. We argue, however, that different types of caregivers, parent-child separation timing, and the duration of parent-child separation may have far-reaching influence on DS and AS among LBC. Therefore, the present study aimed to understand the nature of the relationship between DS and AS in LBC and their left-behind characteristics; this knowledge can inform the development of effective measures for addressing psychological health concerns among LBC.