The following is the summary of “Somatic symptoms mediate the association between subclinical anxiety and depressive symptoms and its neuroimaging mechanisms” published in the December 2022 issue of Psychiatry by Kong, et al.

Low-level anxiety, depression, and physical problems all appear to be linked. However, whether or not somatic symptoms moderate the connection between subclinical anxiety and depressive symptoms and what neuroimaging processes underlie the mediation effect is still up for debate. From the Human Connectome Project, researchers  acquired data on 466 healthy individuals and 53 individuals with major depressive illness who were in remission. Anxiety, depression, and somatic symptoms were evaluated using the Achenbach Adult Self-Report. Resting-state functional magnetic resonance imaging was made 4 times on all individuals. Researchers used mediation analyses to probe the connections between these signs and the neural circuits that may be to blame.

Subclinical anxiety was associated with depressive symptoms, and somatic symptoms mediated this relationship, both in healthy participants(anxiety→somatic→depression: effect: 0.2785, Boot 95% CI: 0.0958–0.3729; depression→somatic→anxiety: effect: 0.0753, Boot 95% CI: 0.0232–0.1314) and participants in remission of MDD (anxiety→somatic→depression: effect: 0.2948, Boot 95% CI: 0.0357–0.7382; depression→somatic→anxiety: effect: 0.0984, Boot 95% CI: 0.0007–0.2438).   (effect: 0.0020, Boot 95% CI: 0.0003-0.0043), with resting-state functional connectivity (FC) between the right medial superior frontal gyrus and the left thalamus and somatic symptoms as chain mediators. As chain mediators, the impact of SDS on SAS in remission from MDD (effect: 0.0437, Boot 95% CI: 0.0024-0.1190) was largely mediated by the mean intensity of common FCs of SDS and SAS. 

The insula, precentral gyrus, postcentral gyrus, and cingulate gyrus were often affected regions in these frequent FCs. Subclinical anxiety, depression, and somatic symptoms during remission from MDD were positively correlated with FC between the triangular section of the left inferior frontal gyrus and the left postcentral gyrus (FDR-corrected P<0.01). Subclinical anxiety and depression interact through somatic symptoms in part. The FCs that may underlie the mediating effect of somatic symptoms are located in the bilateral insula, precentral gyrus, postcentral gyrus, cingulate gyrus, and right medial superior frontal gyrus.