Materials and Methods
This study adopted a cross-sectional survey. From February 2 nd to February 5 th , 2023, a convenience sampling was used to recruit 737 college students for a questionnaire survey at Chongqing Medical University. Posters, applets, QR codes, and links were utilized to disseminate and recruit research subjects. The inclusion criteria for this study were students who were enrolled in Chongqing Medical University (including undergraduate, graduate, and doctoral students) and were willing to participate in this study. Respondents were briefed by professional investigators on the survey content and purpose prior to the survey to seek informed consent. If the subject was underage, investigators obtained informed consent from their guardians via the Internet in advance. The questionnaire included the basic demographic variables, the Appearance Anxiety Scale-Brief Version (AASBV), the Perceived Social Support Scale (PSSS), the SCL-90 Interpersonal Sensitivity Subscale, and the Patient Health Questionnaire (PHQ-9). The questionnaires were distributed and collected relying on the Questionnaire Star platform online. The inclusion criteria were that the results of questionnaires have no missing items, obvious logical errors, and invalid numbers ( e.g ., the ones whose height is over 2.5 m or less than 1 m; the ones whose weight is less than 30 kg or more than 125 kg; the ones whose age are below 16 or bigger than 36). More precisely, all the participants were university students at Chongqing Medical University and after removing missing and invalid data, the remaining sample size was 724.

Appearance anxiety was measured by the Appearance Anxiety Scale-Brief Version (AASBV) written by Keelan, Dion & Dion (1992) . The Appearance Anxiety Scale-Brief Version consists of 14 items. A 5-point Likert scale ranging from 1 (never) to 5 (almost always) is used, which reflects the respondents’ combined attitudes toward appearance anxiety with a total score ranging from 14 to 70. The higher the overall score is, the higher the degree of appearance anxiety is ( Jin et al., 2022 ). The chosen Chinese version of the Appearance Anxiety Scale is a short version of good reliability and validity and the Cronbach’s alpha measured was 0.876.

The Perceived Social Support Scale (PSSS) is used to measure social support ( Tonsing, Zimet & Tse, 2012 ). Response to an item was measured on a 7-point Likert scale, ranging from 1 (strongly disagree) to 7 (strongly agree). It has 12 items in total, and the total score reflects the total social support felt by the individual. The scale has three dimensions: family support, friends support, and others support. The overall score between 12–36 is a low support status; 37–60 is a medium support status; 61–84 is a high support status; the higher the overall score is, the higher the individual’s social support people have ( Ye et al., 2022 ). In this study, the Cronbach’s alpha for the scale was 0.930.

The Symptom Check List-90 (SCL-90) is used to assess respondents’ interpersonal sensitivity ( Dang et al., 2020 ). The SCL-90 invented by Derogatis can be used to assess the intensity of self-reported symptoms, and the scale contains several subscales. The Interpersonal Sensitivity Subscale (nine items in total), one of the subscales, is used to assess the intensity of interpersonal sensitivity among students at Chongqing Medical University. Responses to items are measured on a 5-point Likert scale (0 = none 4 = critical), with a total score ranging from 0–36. Subscale score greater than 2 indicates a psychological abnormality ( Cai et al., 2020 ). The Cronbach’s alpha measurement for this subscale is 0.855, which is more than 0.8 with high reliability.

The Patient Health Questionnaire (PHQ-9) is used to measure depression ( Kroenke, Spitzer & Williams, 2001 ). PHQ-9 consists of nine items for depression self-assessment. The scale was widely used because of its efficiency and convenience. It was rated on a 4-point Likert scale with a score ranging from 0 to 3 and a total score range of 0–27 on the scale. The cut-offs have been proposed as 0–4, 5–9, 10–14, 15–19, and 20–27 for no, mild, moderate, moderately severe, and severe depression respectively ( Furukawa et al., 2021 ). The Cronbach’s alpha for this component in this study was 0.852.

This study used the Statistical Package for the Social Sciences (SPSS) version 25.0 (IBM Corp., Armonk, NY, USA) to analyze the data. Continuous variables are represented using mean and standard deviation (M ± SD), and categorical variables are expressed as frequency and percentage (n(%)). Normality tests and uniformity of variance tests are performed for the measurement of AA, IS, SS, and depression scores under different basic demographic characteristics. Further, a t-test on two independent samples or variance homogeneity is performed to determine whether there was a difference in the mean values of AA, IS, SS, and depression between different subgroups when all samples were satisfied. Pearson’s correlation was used to analyze the correlations between the appearance anxiety, social support, interpersonal sensitivity, and depression. To further understand the relationship between the above variables, a serial multiple mediation model (model 6) was performed using the PROCESS macro 3.5 package provided by Hayes ( Xian et al., 2023 ). Gender and age were used as covariates, appearance anxiety as the independent variable (X), interpersonal sensitivity and social support as mediating variables (M1, M2), and depression as the dependent variable (Y). After the model was built, the mediation effects were tested using a bootstrap (5,000 bootstrap samples) based on 95% confidence intervals. If the 95% confidence interval for the mediating effect does not include zero, the mediating effect will be significant at the 0.05 level. The model of this study was tested to be significant at the 0.05 level.