To the best of our knowledge, this is the first study to investigate the association of sarcopenia, dynapenia and presarcopenia with depression and anxiety in a multi-center hemodialysis population. We found that both sarcopenia and dynapenia were associated with depression but not anxiety among patients undergoing hemodialysis. These findings highlight the importance of integrating of muscle mass and muscle function into clinical practice throughout the dialysis treatment to prevent depression disorders.
This study shows that the prevalence of depression and anxiety are 14.9% and 7.9%. Dano et al. and Mapes et al. reported that the prevalence of depression in hemodialysis patients was 19% and 20%, respectively. Similarly, Mohamed et al. showed the prevalence of anxiety was 7%. However, it is important to note that the prevalence of depression and anxiety was notably lower than the estimated prevalence of 22.8%-39.3% for depression and 12%-52% for anxiety reported in comprehensive systematic reviews[29, 30]. It is worth pointing out that one reason why the prevalence of depression in this study is lower than other studies is that the cut-off of PHQ-9 score in this study is greater than or equal to 10. This means that only grades above moderate depression are included. It was proved to be reliable and valid to detect depression determined by this cut-off in dialysis patients (sensitivity = 92%, specificity = 92%)[31]. While many studies use the same scale as ours, they used a PHQ-9 score ≥ 5 as a reference[32]. There is some mild depression mixed in, so this also partly explains why their prevalence is higher than our results. Using the same scale, Nguyen et al. reported that the prevalence of depression in hemodialysis patients was 42.5% (5 as the cutoff). When using 10 as the cut-off, the prevalence of depression was 12.6%, which is consistent with the results of this study. Another possible reason is that people in Shanghai of China have a better economic status, and the universal health insurance system allows all dialysis patients to get better treatment, which also reduces their psychological pressure to a certain extent. It is estimated that 7–8% of patients seen in a primary care setting have a diagnosis of anxiety disorder[33]. To some extent, it indicates that the patients in this study had a relatively low anxiety level; on the other hand, it indicates that more professional personnel or tools are needed to accurately diagnose anxiety.
Our findings regarding the association between sarcopenia and depression align well with those of previous studies conducted among the general population[10] and patients undergoing the hemodialysis[12–14]. However, compared with the three previous studies on dialysis, our study differs in several aspects. First, the diagnosis of sarcopenia in Kim et al. 's study was incomplete, using only muscle mass and muscle strength to diagnose sarcopenia[13]. In addition, the sample size of Kim et al.’s study[13] included 95 hemodialysis patients, while that of Khoury et al.’s study[14] only contained 42 patients on hemodialysis, both of which had certain limitations. Our study used the 2019 new version of the AWGS criteria to diagnose sarcopenia and included 7 hemodialysis centers with a sample size of more than 1000 individuals. Second, although Kurita et al. found that depression was associated with sarcopenia in dialysis patients, the study mixed peritoneal dialysis as well as non-dialysis chronic kidney disease patients. Similarly, the diagnosis of sarcopenia in this study was not rigorous, using only a questionnaire, and some of the potential confounders of sarcopenia were not collected in the study, such as nutritional measures[12]. Our study addresses these limitations well, but further longitudinal studies are needed to confirm our results. Studies on the association between anxiety and sarcopenia are very rare, with only one report to date, and the conclusion is inconsistent with the finding of our study[14]. Part of the reason for the difference is that the sample size of that study was only 42 hemodialysis patients, and other difference may be in the setting of the pandemic, inflation, and the Beirut blast. Further studies are needed to confirm the relationship.
Some previous studies have demonstrated that dynapenia is associated with mental health in older adults[15, 16] and obese patients[17]. Presently, no study has explored the link between dynapenia and depression and anxiety in patients on hemodialysis. This study was the first to demonstrate that dynapenia is associated with depression in hemodialysis patients. Although there are no studies of dynapenia and depression in dialysis populations, there is still a link between a certain element such as muscle strength and depression, and the finding is consistent with ours. Zhang et al.[6] suggested that lower muscle strength is associated with a higher prevalence of depression in Chinese patients undergoing hemodialysis. Our study also found no evidence that dynapenia was associated with anxiety. This finding is consistent with the only study conducted to date which found no associations between dynapenia and anxiety in older adults[16]. Further research is needed to determine whether the selected GAD-7 recognizes anxiety states in hemodialysis populations that are associated with dynapenia, which would also aid in development of interventions.
The mechanism underlying the associations between sarcopenia and dynapenia with depression are not clearly understood but appear to be complicated and multifactorial. Studies have shown that skeletal muscle, as an endocrine organ, can secrete myokines. Muscle contraction leads to changes in the skeletal muscle environment, which can affect the physiological state of myokines[34]. It is worth noting that myokines can improve brain function. Several studies have shown that a variety of myokines, such as brain-derived neurotrophic factor[35], irisin[36], etc., can act on the nervous system through gene regulation and various endocrine signaling pathways. Moreover, depression has been consistently related to a low-grade inflammatory state[37]. The decrease of inflammation and oxidative free radicals may reduce the risk of depression by improving muscle function[38, 39]. Psychosocial mechanisms may also at least partly explain the associations between sarcopenia, dynapenia and depression in the current study. Depressed hemodialysis patients typically experienced a decrease in physical activity, thereby declining the likelihood of social contact with others and increasing the likelihood of developing depression through a vicious cycle.
We believe that the present findings suggest that strategies to increase muscle mass and function may provide suitable adjunctive treatments for depression among hemodialysis population. Thus, this highlights a need for nephrology physicians and co-medical staff to pay attention to these patients. Emerging evidence indicates that resistance training and nutritional supplements may improve depression among older adults[40, 41]. Early screening and management of musculoskeletal disorders, and encouraging patients to engage in effective exercise and nutritional programs may help reduce the likelihood of developing depression.
Our study also confirmed the association of nutritional status, comorbidity and dialysis efficiency with depression. More details of the relationship between malnutrition and depression can be found in our previous study[20]. In fact, patients on hemodialysis usually have poorer disease status and numerous complications. Our study showed that patients undergoing hemodialysis with more comorbidities were at elevated risk of depression. In addition, effective hemodialysis efficiency is associated with a lower risk of depression.
This study has several strengths. To our knowledge, this is the first study to examine the association between sarcopenia, dynapenia, and depression and anxiety in a multi-center hemodialysis population. Understanding this association is essential for the prevention and treatment of mental disorders in patients on hemodialysis. Second, we used new version criteria to diagnose sarcopenia and dynapenia, as opposed to other studies that used only one element. However, several limitations should be considered.
This study is based on a cross-sectional design. Thus, it is not possible to elucidate clear causal associations among sarcopenia, dynapenia and depression in the patients receiving hemodialysis. More prospective cohort studies are needed for further investigation.
In conclusion, our study showed that sarcopenia as well as dynapenia were associated with a higher risk of depression rather than anxiety in patients undergoing hemodialysis, therefore suggesting that improving muscle mass and muscle function may have potentially beneficial effects on depression. Furthermore, the association between sarcopenia, dynapenia and depression in patients on hemodialysis should be investigated in a large cohort study to clarify this finding.