The following is a summary of “Disentangling the relationship between depression and chronic widespread pain: A Mendelian randomisation study,” published in the June 2023 issue of the Seminars in Arthritis and Rheumatism by Zhao et al.

Depression and widespread chronic pain (CWP) frequently coexist, but it is unknown whether depression is an independent risk factor for CWP or vice versa. Researchers examined the two-way causal connection between depression and CWP. Using extensive population-level genetic data, they conducted a two-sample Mendelian randomization (MR) study to estimate the causal relationship between genetically predicted depression (170,756 cases, 329,443 controls) and risk of CWP (6,914 points, 242,223 controls), as well as the effect of CWP on depression susceptibility. 

In addition to traditional MR and sensitivity analyses, they employed a new MR technique, Causal Analysis Using Summary Effect estimates (CAUSE), which permits sample overlap. The risk of widespread chronic pain increased with each doubling genetic susceptibility to depression (OR 1.004, 95% credible interval 1.003–1.005; p = 7.3 x 10^-5, indicating that the causal model is a superior fit than the non-causal model). There was evidence of causality in both directions, with genetic susceptibility to widespread chronic pain increasing depression susceptibility (OR 2.31; 95% CrI 1.57, 3.40; p = 0.0026, indicating that the causal model is more appropriate). 

Other MR techniques yielded concordant outcomes. This study provides evidence for a bidirectional causal relationship between depression and an increased risk of widespread chronic pain while overcoming the main limitations of previous epidemiological research. Chronic pervasive pain may be prevented or alleviated through interventions for depression and vice versa.

Source: sciencedirect.com/science/article/pii/S0049017223000288