Our study revealed the following major findings: 1) the prevalence of self-reported depressive, anxiety, and comorbid depressive and anxiety symptoms among university students was 16.3%, 24.9%, and 13.3%, respectively; 2) female gender, parental relationships, and annual household income were risk factors for depressive and anxiety symptoms among university students; and 3) the prevalence of FC among university students was 22%, and was 1.81 fold higher among students with depressive symptoms than students without depressive symptoms. To the best of our knowledge, this is the first large-scale investigation of depressive and anxiety symptoms and their influencing factors among Chinese university students.
Regarding the first finding, although epidemiologic surveys of depressive and anxiety symptoms among university students have been conducted, the results have been inconsistent. For example, the meta-analysis by Jahrami et al. reported a global prevalence of 32.5% for both depression and anxiety among students [49], while Martínez-Líbano et al. reported percentages of 63.1% and 69.2% for depression and anxiety [50], respectively. Ramón-Arbués et al. reported results of 3.8% and 24.5% for depressive and anxiety symptoms, respectively, among students [33]. Finally, two studies reported the prevalence of depressive symptoms among Chinese university students to be 28.4%, while that of anxiety ranged from 7.4–43% [51, 52]. These discrepancies in results may be related to different ethnicities and cultural backgrounds of students, as well as the survey instruments and research methods used to collect and analyze the data. Notably, the emergence and ongoing threat of COVID-19 over the past few years has increased the prevalence of depressive and anxiety symptoms among college students. Indeed, previous studies have reported the prevalence of depression and anxiety among college students during the COVID-19 pandemic [53–56] and, although the results were varied, the overall findings indicated that the status of mental health among college students was of concern.
In the current study, the prevalence of comorbid depressive and anxiety symptoms among university students was 13.3%, a finding that highlights the overlapping nature of these two mental health conditions. Interestingly, a network approach study suggested that the most influential central symptom in the depression-anxiety comorbidity profile trended away from the sad mood of depression toward the excessive worry of anxiety [17]. Another systematic review and meta-analysis conducted on cognitive behavioral therapy for the treatment of anxiety among university students reported that comorbid depressive symptoms need to be addressed as well to improve the treatment outcome [57]. Furthermore, the distribution of severity of depressive and anxiety symptoms revealed a stratification of depressive and anxiety symptoms among university students. Our findings were consistent with those of Piscoya-Tenorio et al. and Meda et al. in that a decreasing trend in the prevalence of depressive and anxiety symptom severity from mild to severe was observed [58, 59]. In contrast, an increasing trend was reported in the study of Rabby et al [60]. Inconsistent results may be related to the survey instrument utilized, culture, professional background, economic status, etc. Overall, the findings indicate that early identification of depressive and anxiety symptoms in the university setting is needed to implement early intervention strategies.
Another major finding of the current study was that female gender, poor parental relationships, and lower household income were risk factors for depressive and anxiety symptoms among university students. Previous studies have reported that variations in factors such as hormone levels, socio-cultural factors, and stress coping styles among females were significantly associated with symptoms of depression and anxiety [59, 61–64]. Strained or conflicted relationships between parents may weaken an individual's social and emotional support system, thus increasing vulnerability to stress and serving as a risk factor for depression and anxiety [65, 66]. Family income may increase psychological stress, which is further compounded by academic and employment duties, contributing to the development of emotional problems and feelings of anxiety [67–69]. In addition, there are many more factors that may influence the psychological state of university students, such as age, inappropriate use of electronic devices, lower psychological resilience, and parental mental state [35, 36, 70, 71]. Overall, the previous and current findings underscore the important roles of gender and family background in symptoms of depression and anxiety, and warrant further attention.
The final major finding of the present study was that the prevalence of FC among university students was 22%, and was 1.811 times higher among university students with depressive symptoms than those without. This finding indicates that FC and depressive symptoms may have a close association. Indeed, gastrointestinal function was significantly reduced in rat models of depression and constipation. Furthermore, the authors found that metabolites associated with depression and constipation disrupted energy and amino acid metabolism and dysregulated the function and composition of the intestinal flora [72]. Genome-wide pleiotropic analysis demonstrated that pleiotropic genetic determinants of the association between gastrointestinal disorders and psychiatric disorders were widely distributed across the genome [73]. These findings support a common genetic basis for gastrointestinal and psychiatric disorders including depression, which may be jointly pathogenic. Furthermore, a study that included more than 1.25 million hospitalized patients with irritable bowel syndrome showed that constipation increased the odds of depression, anxiety, and increased hospitalization time in patients with comorbid depression and anxiety [74]. The classic mechanism hypothesis is that there is a vicious cycle between neuroinflammation, the microbiota-gut-brain axis, and symptoms of depression [75]. Indeed, a high proportion of FC patients may have depressive symptoms and, in turn, a high proportion of FC is diagnosed in depression. Furthermore, FC may also be a component of somatization symptoms of depression, which also explains the increased proportion of FC among students with depressive symptoms compared to those without, and warrants further investigation.
Our findings have clinical and policy implications. First, higher education institutions should enhance the attention paid to student mental health issues by increasing outreach and education about mental health and providing more resources, such as counseling and self-screening services, to help students identify and cope with challenges at an early stage. Second, institutions of higher education should engage in cross-collaborations, such as joining mental health services with student health centers, to provide students with a range of integrated health services. Third, a multi-tiered support system is needed. Specifically, students with mild symptoms may benefit more from low-intensity interventions such as mental health education and self-help strategies, while students with moderate to severe symptoms may need more specialized counseling or therapy. Finally, institutions of higher education should enhance students' mental resilience and coping skills by providing mental health counseling, providing mental health courses and activities, and establishing emergency intervention mechanisms for responding to mental health crises.
Nevertheless, there were several limitations to this study. First, the dataset was based on an online survey and self-reported, and may have been subject to selection bias or recall bias. Second, the cross-sectional design of the study limited our ability to infer causal relationships. Future research should use a longitudinal design to better understand the trajectory and causality of mental health problems. Finally, the present study failed to cover all possible risk factors, such as individuals' coping strategies, quality of social support, and online social behaviors, all of which need to included in future research.
In conclusion, the present study demonstrates the high prevalence of depressive and anxiety symptoms, as well as their severity distribution, among university students. Female gender, parental relationships, and household income were risk factors for depressive and anxiety symptoms among university students. Meanwhile, FC was a risk factor for depressive symptoms and there was evidence that the two conditions may interact. These findings should be used to improve the effectiveness of university mental health services and increase awareness of depression and anxiety and their influencing factors among university students, to further promote mental health.[67]