Relationship between Depressive Symptoms and Stress in individuals with infectious history of COVID-19: Mediating Effect of purpose in life

Background: Corona Virus Disease 2019 (CVID-19) is spreading across the world and the epidemic is also a great stress event for individuals which may trigger lots of mental health issue. This study aims to investigate the relationship between depressive symptoms and stress in individuals with infectious history of COVID-19 in Wuhan and the mediating effect of purpose in life. Method: A total of 128 individuals with infectious history of COVID-19 who were discharged from designated hospital and furtherly accepted health management of 14-day rehabilitation, isolation and medical observation at Qingshan District Rehabilitation Station in Wuhan were selected for the testing of Center for Epidemiologic Studies Depression Scale (CES-D), Impact of Event Scale (IES) and purpose-in-life test (PLT). Results: The depressive emotion, somatic symptoms and total score of CES-D in male group were signicantly lower than that of in female participants (P (cid:0) 0.001). The total score of CES-D was negatively correlated with all factors of PLT and positively correlated with all factors in IES (P (cid:0) 0.05 or 0.01). The feeling of life, life goal, intrusiveness and awareness had signicant predictive effects on the total score of CES-D(P (cid:0) 0.05 or 0.01), which could explain 69.3% of variations in the total score of CES-D. The purpose in life played a partial mediating effect between the stress and depressive symptoms in individuals with infectious history of COVID-19, and the mediating effect accounted for 13.33% of the total effect. Conclusions: The females with infectious history of COVID-19 had more severe symptoms of depression. The stress of COVID-19 infectious history had predictive effect on depressive symptoms and purpose in life was mediator between stress and depressive symptoms.


Background
Major stress events, including earthquakes, wars, tra c accidents, tsunami, typhoons and epidemics of infectious diseases, may cause serious impacts on people's mental health and resulted in a variety of mental disorders(e.g. psychosomatic diseases, affective disorders or behavior disorders). In the last two decades, there have been great outbreaks of infectious diseases around the globe or local world, including severe acute respiratory syndrome (SARS) in 2003, the Ebola virus disease (EVD) in 2014, and Corona Virus Disease 2019  in 2019, some of which were regarded as major public health crises of global concerns. The previous literatures showed that the outbreaks of infectious diseases greatly impacted mental health of the public, especially infected persons and medical workers in the front line of treatment. In one study, pregnant women in Hong Kong were investigated for psychological and behavioral reactions to SARS, in which only found result of higher anxiety level, but depressive symptoms before and after SARS were not signi cantly different [1] . The study of Elhai, et al found that during the epidemic of COVID-19, anxiety and fear about infectious disease in undergraduates could predict their depression, pathological use of smart phones and the overall anxiety level, with incidence rate of 2.7% and 9.0% for PTSD and depression respectively; sleep duration and sense of fear were risk factors for depression [2,3] . Another survey was conducted for mental health in medical workers treating patients with COVID-19 in Wuhan. The stress level was found to be signi cantly higher in these medical workers than those treating patients with SARS, with the incidence rates of 54.2%, 58% and 78.4% in anxiety, depressive symptoms and sleep respectively. The gender, title, Precaution strategy and contact history were risk factors of their depression and anxiety [4,5] . Neuropsychological problems among EVD survivors were analyzed systematically in a review and concluded that depression, insomnia, fatigue, anxiety and PTSD were common sequelae [6] .
The currently available studies have payed more attention to mental health of the public and medical workers during the epidemic of infectious diseases, long-term psychological consequences of survivors and risk factors, but fewer studies involve in exploring psychological problems of patients in onset, convalescence and protective factors of mental health. The mental health of patients in onset and convalescence may affect treatment response, convalescent effect and the incidence rate of long-term mental disorders. Effects of mental problem on COVID-19 maybe in two approaches: Firstly, distress, depression and stress correlated directly with function of immune system, thus affecting the onset, treatment response and prognosis of respiratory diseases [7,8] ; secondly, depression and anxiety lead to social withdrawal, lack of mental & physical vitality, diminished capacity for will and movement in patients with COVID-19 [9] , which may have a serious effect on their rehabilitation in psychosomatic function. A study have indicated that some personality variables, including purpose in life, were protective factors of individuals' mental health and enable them to respond to di culties in life with a positive attitude and stress-coping strategies [10] . So purpose in life may be a protective factor of mental health for individuals with infectious history of COVID-19.
At present, COVID-19 has been spreading across the world and the epidemic is also a great stress event for each individual. Compared with earthquakes, serious car accidents and other disaster events, the psychological effects of COVID-19 on individuals may be manifested in the following aspects: rst, invisibility, high infection rate and various routes of transmission; second, persistence; third, the emergency state and isolation measures taken by governments of various countries have disturbed people's routine life and production order; and fourth, high risk of sequelae, such as impaired lung function, reproductive and neuronal degeneration [11,12] . The present study

Psychological Assessment Tools
The Center for Epidemiologic Studies Depression Scale (CES-D) CES-D was developed by Sirodff at National Institute of Mental Health (NIMH) in 1977 and now widely used to screen depressive symptoms in general population of young adults, teenagers and the elderly. CES-D, included 20 items, among which 4 items were scored in reverse, could be assigned into 4 factors: depressive emotion, positive emotion, somatic symptom and interpersonal problems. The frequencies of symptoms in the last one week are graded at 0 to 3, and the total score ranges from 0 to 60 [13] . The CES-D is widely used in China and has good reliability and validity. The reliability coe cient of Cranach's α in this study was 0.83.
The Impact of Event Scale (IES) IES was used to assess stress responses of individuals of being impacted by stress events. The IES includes 22 items that could be divided into three factors: intrusiveness, avoidance and alertness. Each item of the IES was scored ranging from 0 to 4; and the higher the score, the more severe the stress response [14] . The reliability coe cient of Cranach's α in this study is 0.80.
Purpose-in-life Test (PLT) PLT, developed by Crumbaugh in 1968, was used to evaluate the degree of perceived meaning and purpose in life. PLT was composed of 4 factors including 20 items: feeling of life, life goal, life attitude and life control. Each item was scored ranging from 1 to 7 and the total score ranges from 20 (low purpose) to 140 (high purpose). PLT have been used to assess the purpose in life in different population [15] . The reliability coe cient of Cranach's α in this study is 0.88. in Qingshan District, Wuhan and their centralized isolation after negative in nucleic acid tests, with random allocation for rooms), based on the principle of informed consent, anonymity and limited time. At the beginning of the survey, the investigative goal, participants' rights of quitting for mental and physical discomforts and free interventions for discomfort relating to this survey were presented to the participants. After informed consent was obtained, they could click the next step and complete the formal questionnaire. All questions in the questionnaire must be answered, only one chance for the same mobile phone number. A questionnaire that had all options completed without repeated answers or abnormal values was considered valid. A total of 134 questionnaires were received, including 128 valid questionnaires, with the received valid rate up to 95.5%. Statistical analysis SPSS20.0 was used for data management and statistical analysis. The relationship between depressive symptoms and stress or purpose in life in individuals with infectious history of COVID-19 was analyzed using statistical methods such as paired-samples T test, correlation analysis and hierarchical regression analysis. P 0.05 indicates that the difference was statistically signi cant.

Results
Gender differences in depressive symptoms in individuals with infectious history of COVID-19 To con rm the gender differences in depressive symptoms in individuals with infectious history of COVID-19, independent-sample T test was carried out. From Table 1, depressive emotion, somatic symptom and total score of CES-D in male patients are signi cantly lower than those in female patients (P 0.001).  Note: * Represents P < 0.05, and ** Represents P < 0.01.

Pearson correlation test of depressive symptoms and stress, purpose in life in individuals with infectious history of COVID-19
According to the results from the Person correlation analysis of the relationship between depressive symptoms and stress / purpose in life in individuals with infectious history of COVID-19, the total score of CES-D was signi cantly negatively correlated with all factors of PLT (P 0.05 or 0.01), and positively correlated with all factors of IES (P 0.01).

Regression analysis of factors affecting depressive symptoms in individuals with infectious history of COVID-19
The results of the multiple regression analysis using the total score of CES-D as the dependent variable and the factors in PLT and IES as independent variables showed that the feeling of life, life goal, intrusiveness and alertness had signi cant predictive effects on the total score of CES-D (P < 0.05 or 0.01), which could explain 69.3% of variations in the total score of CES-D.

Analysis of mediating effect of purpose in life between depressive symptoms and stress in individuals with infectious history of COVID-19
According to the mediating effect testing procedure proposed by Wen Zhonglin [16] , a hierarchical regression analysis method was used to test the mediating effect of purpose in life between depressive symptoms and stress in individuals with infectious history of COVID-19. The procedure consisted of 3 steps: (1) performing regression analysis using the total score of IES as the predictive variable and the total score of CES-D as the dependent variable; (2) performing regression analysis using the total score of IES as the predictive variable and PLT as the dependent variable; and (3) performing regression analysis using the total scores of IES and PLT as the predictive variables and the total score of CES-D as the dependent variable. From the direct effect to the mediation model, stress still had a signi cant predictive effect on the depressive symptoms of individuals with infectious history of COVID-19 (P 0.000). When the path coe cient decreased, the purpose in life produced a partial mediating effect between stress and depressive symptoms in individuals with infectious history of COVID- 19. The mediating effect accounted for 13.33% of the total effect. See Table 4.

Discussion
In major disasters and during the post-disaster recovery process, there is an increase in the incidence of mental illness such as depression, post-traumatic stress disorder, insomnia, obsessive-compulsive disorder and suicide [17,18] . Psychological trauma repair is an important component of post-disaster recovery. Different from common natural disasters [11,12] , COVID-19 has serious effects on human life, health, economic activity and living order etc., and may lead to damage to the mental of patients.
The present study found that the depressive emotions, somatic symptoms and CES-D score in male patients were signi cantly lower than those in female patients. In other words, female group developed severer depressive symptoms than the male controls. These results differ from those of other studies. The study of Kuang Chunyan et al did not found that the depression degree of COVID-19 was different signi cantly in gender group [19] . This may be related to different sampling sites. For this study, participants were recruited from Wuhan, Hubei, with a centralized outbreak of COVID-19 in China. The epidemic caused serious impact to local normal economic activities and supply of living materials and brought heavy pressure to medical system and resources. As Chinese government promptly took strictest preventive measures, the epidemic could be controlled in other regions outside Hubei, patients and their family members had adequate con dence in defeating the epidemic at a low level of the overall social emergency atmosphere, and the depression degree did not have a signi cant difference between patients in gender. However, in Wuhan, the interaction of the stressful overall social atmosphere, the gender role and personality traits of females and other factors caused severer depression symptoms in females. Investigators found that females were prone to paying attention to, indulging in and ruminating on negative information. According to the investigators, this rumination was a vulnerable response strategy that would put patients in a vicious circle of immersing in negative information [20. 21] and make them even more pessimistic and inactive towards treatment, rehabilitation and future life. In addition, females would be more likely to have personality traits such as sensitivity, fragile and suggestibility [22,23] , so that they tend to magnify the negative information they received, underestimate their response capabilities and physical environment, lack of social support, threat of death, and expectation of the low cure rate [24][25][26]  uncertainty. Meanwhile, they may develop fear to death and future, become depressed, pessimistic and hopeless, lower their senses of self-value and control, lose the sense of purpose in life, and exhibit social and emotional alienation [29][30][31] , thus further worsening depressive symptoms and presenting suicidal ideation and attempts.
The implications of this study was to suggest the necessity of enhancing psychological assistance to female population. At the same time, it was required to guide females to give themselves more positive self-suggestions, multi-perspective cognition and analysis of themselves, others, diseases, environment and future life, pay more attention to positive perspectives, plan their present and future lives and de ne their purpose and direction in life, and avoiding clutter and aimlessness. These actions are bene cial to psychological rehabilitation, and provide scienti c basis for interventions of psychological crises in females during the COVID-19 epidemic.
This study is a cross-sectional study, with the limitation that the long-term psychological effect of COVID-19 infection, treatment, isolation, impaired somatic function and stigmatization on patients cannot be observed. Some studies have demonstrated long-term and potential damage of infectious disease to individuals' mental health [32] . Thus, future studies are required to trace and observe relevant situations, evaluate psychological problems in patients with COVID-19 and propose necessary measures for intervention and rehabilitation training of social function.

Conclusions
Female group with infectious history of COVID-19 presented severer symptoms of depression. Stress had a signi cant predictive effect on the depressive symptoms in with infectious history of COVID-19, and the purpose in life had a partial mediating effect between stress and depressive symptoms.

Declarations
Ethical Approval and Consent to participate The study was been approved by the Ethics Committee of Luoyang No. 5 People's Hospital (Ethics Approval No.: 2020-02-Study) and the informed consent of all subjects had been obtained.

Consent for publication
Not applicable.
Availability of supporting data The datasets are available from the corresponding author upon reasonable request.