Cytokine alterations in panic disorder: A systematic review.

BACKGROUND: Panic disorder (PD) occurs in 3.4-4.7% of the general population. Although accumulating evidence suggests that some inflammatory processes play a role in the pathophysiology of mental disorders, very few studies have evaluated cytokine levels in patients with PD. The aim of the present study was to systematically review the characteristic cytokine profile of PD patients and discuss some possibilities for future trials on this common and disabling disorder.
METHODS: A comprehensive literature search was carried out in PubMed and Web of Science databases (search terms: "panic disorder" or "panic attacks" and IL-1, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12, IL-13, TNF-alpha and INF-gamma).
RESULTS: Eleven studies involving measurements of cytokines in PD patients were included in this review article. Increased serum levels of some inflammatory markers such as IL-6, IL-1β and IL-5 were reported in PD patients compared with control subjects. There are some conflicting results regarding IL-2, IL-12, and INF-γ in association with PD. LIMITATIONS: There are discrepant findings in the existing literature regarding PD and cytokines. A significant portion of the recognized heterogeneity may be attributable to variability in assay procedures. The discrepant findings may also have been due to differences in the study populations.
CONCLUSIONS: Cytokines induce the production of acute-phase proteins and are linked to neurogenesis, modification of the HPA axis, microglial activation, tryptophan metabolism and an imbalance in excitatory and inhibitory neurotransmission. Investigation of inflammatory biomarkers in PD could contribute to understanding the pathophysiological mechanisms in this debilitating disorder.