Interleukin-6 and interleukin-17 are related to depression in patients with rheumatoid arthritis

Aim Mood disorders are a serious issue for patients with rheumatoid arthritis (RA) because poor mental health can exacerbate the disease course. This study aimed to identify the effect of proinflammatory cytokines on the mood of patients with RA. Methods This study was conducted at a rheumatology clinic in Northern Taiwan. In total, 113 patients with RA and 42 healthy controls were assessed for anxiety and depression symptoms using Hospital Anxiety and Depression Scale (HADS). RA was assessed using the Disease Activity Score of 28 joints (DAS28). Serum proinflammatory cytokine levels, including interleukin (IL)-1 beta, IL-6, IL-17 and tumor necrosis factor alpha (TNF-alpha) were measured and compared between different patient groups according to disease activity and pain level. Results Serum IL-1 beta, IL-6, IL-17 and TNF-alpha levels were significantly higher in patients with RA than in healthy controls, as were the mean anxiety and depression subscale scores. In patients with RA who had different disease activities, pain severity correlated with both anxiety and depression symptoms. When HADS scores were analyzed according to pain levels, age was correlated with depression in the severe pain group. In the mild pain group, patients with higher IL-6 or higher IL-17 had a higher risk of depression. There was no correlation between mood symptoms and cytokine levels in healthy controls. Conclusion Elevated serum IL-6 and IL-17 levels in patients with RA induce arthritis and cause mood symptoms, especially depression symptoms.