Shifted inferior frontal laterality in women with major depressive disorder is related to emotion-processing deficits

Background. Facial emotion perception (FEP) is a critical human skill for successful social interaction, and a substantial body of literature suggests that explicit FEP is disrupted in major depressive disorder (MDD). Prior research suggests that weakness in FEP may be an important phenomenon underlying patterns of emotionprocessing challenges in MDD and the disproportionate frequency of MDD in women. Method. Women with (n=24) and without (n=22) MDD, equivalent in age and education, completed a FEP task during functional magnetic resonance imaging. Results. The MDD group exhibited greater extents of frontal, parietal and subcortical activation compared with the control group during FEP. Activation in the inferior frontal gyrus (IFG) appeared shifted from a left >right pattern observed in healthy women to a bilateral pattern in MDD women. The ratio of left to right suprathreshold IFG voxels in healthy controls was nearly 3 : 1, whereas in the MDD group, there was a greater percentage of suprathreshold IFG voxels bilaterally, with no leftward bias. In MDD, relatively greater activation in right IFG compared with left IFG (ratio score) was present and predicted FEP accuracy (r=0.56, p<0.004), with an inverse relationship observed between FEP and subgenual cingulate activation (r=-0.46, p=0.02). Conclusions. This study links, for the first time, disrupted IFG activation laterality and increased subgenual cingulate activation with deficient FEP in women with MDD, providing an avenue for imaging-to-assessment translational applications in MDD.