Common Method Bias Test
Considering that all of the data for this study came from the questionnaires, Harman's one-factor method was used to test for possible common method bias. The results showed that 15 factors had eigenvalues greater than 1. The first factor explained 24.6% of the variance, which is less than the 40% threshold proposed by Podsakoff et al. [43]. It is therefore reasonable to infer that the study did not have significant common method bias and meets the statistical requirements.
Descriptive Statistics
Table 1 presents the descriptive statistics and correlation coefficients for stress perception, neuroticism, general self-efficacy, perceived social support, interpersonal distress, and anxiety and depression. The results showed that perceived social support and general self-efficacy were significantly and negatively correlated with depression and anxiety, whereas interpersonal distress, neuroticism, and stress perception were significantly and positively correlated with depression and anxiety.
Table 1
Descriptive statistics and correlation analysis of each variable
Variable | M | SD | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
---|
1 = Stress Perception | 25.040 | 6.007 | 1 | | | | | | |
2 = Neuroticism | 34.740 | 7.614 | 0.688*** | 1 | | | | | |
3 = General Self-Efficacy | 2.666 | 0.407 | -0.411*** | -0.493*** | 1 | | | | |
4 = Perceived Social support | 62.150 | 12.348 | -0.389*** | -0.398*** | 0.296*** | 1 | | | |
5 = Interpersonal Distress | 8.890 | 6.064 | 0.550*** | 0.582*** | -0.430*** | -0.400*** | 1 | | |
6 = Anxiety | 3.670 | 3.823 | 0.627*** | 0.618*** | -0.336*** | -0.366*** | 0.588*** | 1 | |
7 = Depression | 5.130 | 4.311 | 0.618*** | 0.585*** | -0.346*** | -0.410*** | 0.573*** | 0.808*** | 1 |
***P < 0.001 |
Latent Profiles of Depression and Anxiety Symptoms
Model Optimization
In this study, five potential profile models were selected for fitting analysis, and the fitting indices are shown in Table 2. The values of AIC, BIC, and aBIC decreased as the number of classes increased and were lower and similar when they were divided into 3, 4, and 5 categories. The smaller the AIC, BIC, and aBIC values, the better the model fits. In contrast, the larger the Entropy value, the better the model fit, and in general, the closer the Entropy value is to 1, the more accurate the classification. LMR and BLRT were significant, indicating that the addition of a profile significantly improved the model fit. The Entropy value was the highest when divided into 5 categories, followed by 3 categories and finally 4 categories, and the LMR and BLRT values of several groups were significant. However, the probabilities corresponding to 4 and 5 categories were less than 5%, and the proportion of categories needed to be higher, which was of no practical significance. On the basis of these simulations, the models were divided into three optimal types. Table 3 shows that the average attribution probability for different potential categories is between 96%-99%, indicating that the results of these three types of models are credible.
Table 2
Latent profile models for depression and anxiety
Model | AIC | BIC | aBIC | LMR | BLRT | Entropy | Probability |
---|
1 | 57035.861 | 57210.245 | 57108.585 | | | | |
2 | 48215.842 | 48482.868 | 48327.200 | 0.0000 | 0.0000 | 0.938 | 0.693/0.307 |
3 | 44873.127 | 45232.794 | 45023.119 | 0.0000 | 0.0000 | 0.942 | 0.578/0.366/0.056 |
4 | 43712.783 | 44165.092 | 43901.410 | 0.0334 | 0.0000 | 0.902 | 0.442/0.302/0.212/0.044 |
5 | 42162.650 | 42707.600 | 42389.911 | 0.0017 | 0.0000 | 0.957 | 0.517/0.043/0.204/0.198/0.038 |
Table 3
Average attributions for each latent class
class | 1 | 2 | 3 |
---|
1 | 0.978 | 0.022 | 0.000 |
2 | 0.037 | 0.960 | 0.003 |
3 | 0.000 | 0.008 | 0.992 |
Naming Latent Classes
The scores of the three potential classes in terms of the 16 dimensions of depression and anxiety are shown in Fig. 1. The average scores of depression and anxiety in class 1 were 2.44 and 1.12, respectively, and this class exhibited almost no symptoms of depression or anxiety. The class 2 scores in each dimension were significantly higher than those of class 1. Class 2 comprised 36.6% of the participants, whose average scores of depression and anxiety were 7.86 and 6.16, respectively. The scores of class 3 in each dimension were significantly higher than those of the other two categories. Class 3 comprised 5.6% of the participants, and the average scores of depression and anxiety were 15.53 and 13.8, respectively. According the PHQ-9 and GAD-7 scoring criteria (Fig. 1), class 1, 2, and 3 were named “healthy”, “mild depression-mild anxiety”, and “moderately severe depression-moderate anxiety”, respectively. In this study, class 2 and class 3 were considered risk groups for depression and anxiety comorbidity.
Network Analysis
Symptoms of Depression and Anxiety
A network analysis was performed for the risk groups for depression and anxiety comorbidities. The weights of the edges and the positive and negative correlations between the nodes are illustrated in Fig. 2, where GAD2 (“worry out of control”) and GAD3 (“overly worried”) are most closely connected to anxiety items, and PHQ4 (“fatigue”) is most closely connected with PHQ1 (“anhedonia”) among depression items. The strongest connection is between GAD1 (“nervousness”) and PHQ2 (“depressed mood”). Overall, depressive symptoms and anxiety symptoms are closely related, and each symptom affects at least one other.
The centralization results (Fig. 3a) indicate that PHQ2 (“depressed mood”) had the highest EI value among the depression items and had high closeness and strength, highlighting it as a core symptom of depression; it also had the most significant impact on each node in the depression network. Among the anxiety items, GAD4 (“difficulty relaxing”) has the highest EI value, followed by GAD1 (“nervousness”), which also had higher closeness and strength. Similarly, these can be regarded as the core symptoms of anxiety because they had the most significant impacts on each node in the anxiety network. Figure 3b shows that PHQ2 (“depressed mood”) had the highest BEI value and was the most prominent bridging symptom among the depression items. Figure 2 highlights the strong relationship between PHQ2 (“depressed mood”) and many symptoms of anxiety, including GAD1 (“nervousness”), GAD3 (“overly worried”), GAD4 (“difficulty relaxing”), and GAD6 (“irritable”), followed by PHQ9 (“suicidal ideation”), which plays a vital role in the comorbid pathogenesis of depression and anxiety. The most prominent bridging symptom of anxiety was GAD4 (“difficulty relaxing”). Figure 2 indicates that GAD4 (“difficulty relaxing”) had high weights corresponding to its edges with PHQ2 (“depressed mood”), PHQ3 (“sleep disturbance”), PHQ4 (“fatigue”), and PHQ9 (“suicidal ideation”), followed by GAD5 (“restless”). Indeed, most of the depression and anxiety nodes had high BEI values, meaning they can be considered as bridging symptoms that support the comorbidity network of depression and anxiety. According to the stability test, the centrality index of each node and the CS coefficient of the BEI are both 0.7, indicating that after 70% of the data are discarded, the index is still related to the original data (r = 0.7); thus, the network stability is high.
Risk and Protective Factors
Based on the network of depression and anxiety comorbidity, the incorporation of risk and protective factors for network analysis (Fig. 4) revealed that all factors were connected, with neuroticism and stress perception having the strongest correlations with depression and anxiety. Notably, there was a strong positive correlation between stress perception and neuroticism. GAD1 (“nervousness”) and GAD4 (“difficulty relaxing”) represented the EI maxima among anxiety symptoms, whereas PHQ2 (“depressed mood”) exhibited the EI maximum among depression symptoms (Fig. 5a); these factors had the strongest impacts on their respective communities, consistent with the results from the network analysis of depression and anxiety symptoms. Stress perception had the highest EI value among the factors influencing depression and anxiety comorbidity. Stress perception also has the highest BEI value, suggesting that it had the strongest bridging effect (Fig. 5b). Overall, it had a substantial positive correlation with depression and anxiety, followed by neuroticism, which also played a strong bridging role. Meanwhile, interpersonal distress also played a bridging role, although both its bridging role and correlation with depression and anxiety were weaker. The BEI values of perceived social support and general self-efficacy were both extremely low and negative, suggesting that their associations with other nodes were negatively correlated, and there was a positive correlation between the two.
The network stability was very high, with both the node and BEI CS coefficients equal to 0.7; this result indicates that after discarding 70% of the data, both metrics remain relevant to the original data set (r = 0.70). The narrow 95% confidence interval for the edges supports the conclusion that the network exhibits high accuracy.