Statistical analysis
Data were analyzed using SPSS version 20.0 software (SPSS Inc., Chicago, IL, USA). The categorical data were tested using the chi-square test or Fisher's exact test as appropriate. We performed a Shapiro–Wilk test to check the normality of the continuous variables. For data with a normal distribution, one-way analysis of variance (ANOVA) was used to compare baseline characteristics, and the analysis of covariance (ANCOVA) was used to compare post-intervention changes across the four groups, with age (years) and education (years) as covariates. If there is a statistically significant difference between groups for a certain indicator prior to intervention, this indicator will be included as a covariate in the analysis after intervention. 