Objectives: To investigate the prevalence of depression and anxiety symptoms among older adults in an urban district in China, as well as their associated factors.

Participants: A total of 5,372 community-dwelling older adults aged 65 years or older were initially recruited. Ultimately, 5,331 participants met the inclusion criteria and were included in this study.

Methods: Participants completed a sociodemographic questionnaire, along with assessments including the Patient Health Questionnaire-9, Generalized Anxiety Scale-7, UCLA Loneliness Simplification Scale, Insomnia Severity Index Scale, Community Dementia Brief Screening Scale, and the 8-item Dementia Screening Questionnaire. Statistical analyses included the Shapiro‒Wilk test, independent t-test, Wilcoxon rank test, c² test, and univariate and multivariate linear regression analysis.

Results: The prevalence of depression and anxiety symptoms among older adults in Shenzhen communities was 10.4% and 11.3%, respectively. In multivariate analysis, age (B=-0.01, P<0.05), relatively poor health status in the past year (B=1.00, P<0.01), poor health status in the past year (B=2.40, P<0.01), ISI score (B=0.21, P<0.01), AD8 score (B=0.22, P<0.01), ULS score (B=0.24, P<0.01) were significantly associated with the severity of depression symptom, Compared to their respective reference categories, relatively poor health status in the past year (B=0.50, P<0.01), poor health status in the past year (B=1.32, P<0.01), ISI score (B=0.23, P<0.01), sleep duration (B=0.05, P<0.01), AD8 score (B=0.21, P<0.01), CSID score (B=0.13, P<0.01), ULS score (B=0.22, P<0.01) were significantly associated with the severity of anxiety symptom.

Conclusions: We observed a high prevalence of depression and anxiety symptoms among older adults in this study. The existing welfare system and infrastructure should remain and targeted mental health programs addressing the identified risk factors should be proposed.

Study population

This study employed a cross-sectional population-based survey research design and used a multistage random whole-group sampling method to select representative samples from 10 districts in Shenzhen. First, we conducted sampling by region and population distribution based on Shenzhen's 2018 population statistics. One street was randomly selected from each administrative district, and one community was further randomly selected from each street in the first stage. In the second phase, all eligible households were drawn from each of the selected communities. In the final phase, we selected eligible family members from each of the designated families and recruited participants from the selected families from April 2017 to October 2017. To be eligible, participants had to meet the following criteria: (1) aged 65 or above; (2) residing in Shenzhen for at least 6 months; and (3) providing informed consent. Participants were excluded if they refused to sign the informed consent form after repeated explanations by the investigator, could not be located on at least three return visits, or had a history of a serious medical condition that might prevent them from completing the survey.

From October 2020 to February 2021, a total of 5,372 participants were invited to participate in the study and were asked to complete a mental health assessment questionnaire. Of these, 41 participants were excluded due to poor questionnaire completion quality, leaving 5,331 participants (99.2%) for data analysis. All eligible participants received mental health education, and those with abnormal assessment results were referred to the nearest mental health care facility for counselling and medical care.

Before the formal survey began, the research team recruited investigators who were experienced in mental health work and provided them with structured training sessions. The training covered the purpose of this study, community outreach strategies, proper questionnaire administration, and the importance of standardized assessments and research procedures. Investigators utilized various means such as posters, radio broadcasts, and media channels, to promote mental health surveys in the sampled communities and to gain the understanding, attention, and cooperation of the community. Investigators then made individual appointments according to the sample list, explained the purpose of the survey, the process, and the benefits of participation to the respondents, and obtained consent. A specific time for the face-to-face household survey was then determined. As mental health-related issues are sensitive information, we asked all participants to complete the survey in a private one-on-one setting.

Measurements

A structured questionnaire was utilized to gather information on the participants' sociodemographic characteristics and health assessment parameters. The questionnaire required approximately 25 minutes to complete and consisted of four sections, which included sociodemographic characteristics, lifestyle, physical health, and mental health. whether the participants suffer from chronic diseases, is based on the diagnosis of chronic disease by second level and above hospitals. Additionally, a comprehensive self-reported assessment of the participants' health status in the past year was used, with five ratings ranging from good to poor. Drinking behaviour was categorized into three groups: drinkers (1 or more drinks per week), previous drinkers who currently abstain from alcohol, and nondrinkers. Smoking behaviour was classified into three categories: smokers, individuals with a previous history of smoking who currently abstain, and never smokers.

The Patient Health Questionnaire Depression Scale-9 item (PHQ-9) was utilized to evaluate the occurrence of depressive symptoms in the participants. The PHQ-9 comprises nine items that measure the respondent's depressive state and severity in the past year, with each item rated on a four-point scale from 0 (not at all) to 3 (almost every day). The total score ranges from 0-27, with higher scores indicating more severe depression. In this study, we used a score of 5 as the cut-off point, with a score greater than or equal to 5 indicating the presence of depressive symptoms and a score less than 5 indicating the absence of depressive symptoms. The Cronbach's alpha for the scale was 0.805.

The Generalized Anxiety Disorder 7-item scale (GAD-7) was utilized to assess the occurrence of anxiety symptoms in the participants. Respondents recall their anxiety status and severity assessment within the past year, rating each item on a four-point scale from 0 (not at all) to 3 (almost every day), with a total score range of 0–21. Higher scores indicate more severe anxiety in participants. For this study, a score of 5 was used as the threshold, with scores greater than or equal to 5 indicating the presence of anxiety symptoms and scores less than 5 indicating the absence of anxiety symptoms. The Cronbach's alpha for the scale was 0.911.

A simplified version of the UCLA Loneliness Scale (ULS-6) was utilized to evaluate the discrepancy between the respondents' desire for social interaction and their actual level of interaction. The ULS-6 was translated and revised in Chinese and comprises six items, each rated on a four-point scale from 1 (never) to 4 (always). The total score ranges from 6 to 24, with higher scores indicating more severe loneliness. The Cronbach's alpha for the scale was 0.870.

The Insomnia Severity Index (ISI) was utilized to evaluate the occurrence and severity of insomnia in the participants, consisting of seven items. Respondents are asked to recall their insomnia symptoms in the past month. Each item is rated on a four-point scale ranging from 0 (not at all) to 3 (almost every day). The total score ranges from 0–21, with higher scores indicating more severe insomnia symptoms. In this study, a score of 7 was chosen as the threshold, with scores greater than or equal to 7 indicating the presence of insomnia symptoms and scores less than 7 indicating the absence of insomnia symptoms. The Cronbach's alpha for the scale was 0.929.

The Brief Community Screening Instrument for Dementia (CSI-D) was utilized to assess the presence of early dementia among the participants. The scale includes seven cognitive items, which are ranked in descending order of difficulty as follows: describing the purpose of a hammer, naming the elbow, pointing to the window and then to the door, identifying the location of a nearby shop, identifying the current season, identifying the current week, and recalling three words after a delay. The total score on the scale ranges from 0 to 9, with higher scores indicating better cognitive functioning. In this study, a score of 7 was used as the threshold for early dementia, with scores greater than 7 indicating no evidence of early dementia and scores less than or equal to 7 indicating the presence of early dementia. The Cronbach's alpha for the scale was 0.674.

The 8-item Ascertain Dementia Questionnaire (AD8) was utilized to assess early mild cognitive impairment (MCI) on an eight-item scale. These items include diminished assertiveness, reduced engagement in hobbies, repetition of the same thing, difficulty in learning new things, forgetting the current year, difficulty handling complex financial matters, difficulty recalling appointments with others, and problems with memory and thinking. The total score ranges from 0 to 8, with higher scores indicating more severe cognitive impairment. In this study, a score of 2 was used as the nodal point, with scores greater than or equal to 2 indicating possible mild cognitive impairment and scores less than 2 indicating normal cognitive functioning. The Cronbach's alpha for this scale was 0.796.

Statistical analysis

The statistical analysis was conducted using R version 4.1.0. Means and standard deviations are used to describe continuous variables, while frequencies and percentages are used for categorical variables. The Shapiro‒Wilk test was used to check the normality of continuous variables. The Shapiro‒Wilk test was used to check the normality of continuous variables. Student’s independent t-test or Wilcoxon’s rank test was used to compare quantitative variables, depending on the normal distribution test results. The chi-square test was used for categorical variables. The R package "compareGroups" was utilized for descriptive analysis. Dummy variables were created for categorical variables, and the first reference group for each variable was set as the reference group for regression analysis. One-way linear regression was used to identify the factors associated with depressive symptoms and anxiety symptoms. The variables that were statistically significant in the univariate analysis were included in a multifactorial stepwise linear regression model to evaluate the relationship between depressive symptoms and anxiety symptoms. The analyses were performed using the R packages "car" and "MASS". The test level was set to a two-sided alpha of 0.05, and a P-value less than 0.05 was considered statistically significant.