In present study, we found that the prevalence of anxiety among MMT users was 30.5%. We also found that the dosage of methadone in anxiety group was lower than that in non-anxiety group. Compared with the non-anxiety group, the anxiety group had a higher methadone treatment interruption rate. We also found that good life quality and good sleep quality have positive effects on reducing the risk of anxiety.
We found that 30.5% MMT patients suffer from anxiety. The prevalence rate was lower than that shown by previous study conducted in Australia (67.7%) 11, but it was similar to that of another two studies conducted in China (23.0% and 33.6% respectively) 12,13. The discrepancy may due to the cumulative duration of methadone treatment of participants in studies. In a Chinese study12, it was found that the longer the maintenance treatment lasted, the lower the prevalence of anxiety disorders among participants. The methadone treatment time for Australian participants is merely 1 week to 6 months, which is shorter than that in our study. Therefore, it is possible that the duration of methadone maintenance treatment may be a crucial factor affecting the prevalence of anxiety among MMT users. Most of the subjects in this study were accepted in the MMT program more than 12 months and were in stable stage, so the duration of treatment hadn’t showed the obvious influence on anxiety. The influence of the MMT treatment duration on anxiety remains to be further explored.
The methadone therapeutic dose in anxiety group was lower than that in non-anxiety group. This indicates that low therapeutic dose increases the risk of anxiety symptoms. That was consistent with the result of a previous survey conducted in China 10. Higher dose of methadone could reduce heroin craving, inhibit heroin’s euphoric effect, prevent withdrawal symptoms and stabilize the behavior of drug addicts. Moreover, the higher dose of methadone is also related to the MMT retention rate increase and the improvement in treatment effectiveness 25–28. Several studies had suggested that MMT users with mental problems or disorders might need higher therapeutic dose of methadone to get better treatment benefits 25,26.
The overall life quality of the subjects in anxiety group was worse than that of the subjects in non-anxiety group. This result was in line with a previous study which showed that psychiatric problems were associated with lower quality of life 29. The results of correlation analysis also showed that the improvement of life quality has a positive effect on reducing the risk of anxiety. This result is consistent with the results of previous studies suggesting that there is a certain correlation between quality of life and emotional problems of MMT users 30–33. The evaluation of life quality in this study was composed of four dimensions: physical condition, psychological state, social function and withdrawal symptoms. This makes the evaluation more comprehensive. Similar to the results of previous studies, MMT users’ good physical condition, good psychological state, sufficient social support and less withdrawal symptoms had positive effects on reducing the risk of anxiety 29,31,33. Good physical condition and less withdrawal symptoms mean that MMT users will bear less burden caused by physical problems, while good psychological state and good social function mean that MMT users will bear less psychological burden. Therefore, as suggested by previous studies, improving MMT users’ quality of life by improving their physical condition, psychological state, social function and reducing their withdrawal symptoms is an effective way to reduce the risk of anxiety 29,31,34.
The sleep quality of the subjects in anxiety group was worse than that of the subject in non-anxiety group. Moreover, correlation analysis results showed that poor sleep quality was positively correlated with anxiety severity, which is consistent with previous studies 31,33,35−39. Good sleep provides MMT users with opportunities to get adequate physical and mental rehabilitation. A previous study showed that sleep (especially NREM) can calm the anxious brain and restore the prefrontal cortex’s ability to regulate emotions which preventing anxiety from worsening 19. It suggests that improving the sleep quality of MMT users has a positive significance for reducing the risk of anxiety in MMT users.
In order to comprehensively evaluate the impact of life quality and sleep quality on anxiety of MMT users, we put the score of four dimensions of QOL-DA, PSQI score and BAI score into a multiple linear regression model for further analysis. Multiple linear regression model showed that the psychological dimension of QOL-DA had the greatest influence on BAI score. In other words, the factors related to the psychological state of MMT users would affect the life quality of MMT users and thus increase the risk of anxiety. Therefore, psychological intervention seems to be the key breakthrough. However, the majority of methadone treatment clinics and treatment centers in China only provide methadone medication and medication-related counseling for MMT users, and a fraction of treatment centers had social workers in order to assist doctors. Psychological counseling and psychotherapy services are seldom parts of methadone maintenance treatment services in China 34,40. The unmet mental health needs among MMT patients is a key factor affecting anxiety. Therefore, improving the current situation of limited psychological service resources in China and providing psychological intervention services (including psychological counseling, psychotherapy, social-family support) for MMT patients are conducive to reducing the risk of anxiety disorder. This is also advocated by relevant research 34,41.