Anxiety disorders and inflammation in a large adult cohort

Although anxiety disorders, like depression, are increasingly being associated with metabolic and cardiovascular burden, in contrast with depression, the role of inflammation in anxiety has sparsely been examined. This large cohort study examines the association between anxiety disorders and anxiety characteristics with several inflammatory markers. For this purpose, persons (18-65 years) with a current (N = 1273) or remitted (N = 459) anxiety disorder (generalized anxiety disorder, social phobia, panic disorder, agoraphobia) according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria and healthy controls (N = 556) were selected from the Netherlands Study of Depression and Anxiety. In addition, severity, duration, age of onset, anxiety subtype and co-morbid depression were assessed. Inflammatory markers included C-reactive protein (CRP), interleukin (IL)-6 and tumor-necrosis factor (TNF)-alpha. Results show that after adjustment for sociodemographics, lifestyle and disease, elevated levels of CRP were found in men, but not in women, with a current anxiety disorder compared with controls (1.18 (s.e. = 1.05) versus 0.98 (s.e. = 1.07) mg l(-1), P = 0.04, Cohen's d = 0.18). No associations were found with IL-6 or TNF-alpha. Among persons with a current anxiety disorder, those with social phobia, in particular women, had lower levels of CRP and IL-6, whereas highest CRP levels were found in those with an older age of anxiety disorder onset. Especially in persons with an age of onset after 50 years, CRP levels were increased compared with controls (1.95 (s.e. = 1.18) versus 1.27 (s.e. = 1.05) mg l(-1), P = 0.01, Cohen's d = 0.37). In conclusion, elevated inflammation is present in men with current anxiety disorders. Immune dysregulation is especially found in persons with a late-onset anxiety disorder, suggesting the existence of a specific late-onset anxiety subtype with a distinct etiology, which could possibly benefit from alternative treatments.