Temporal lobe dysfunction for comorbid depressive symptoms in postherpetic neuralgia patients

Depression often occurs concurrently with postherpetic neuralgia (PHN), yet the neural mechanism underlying pain-depression comorbidity remains poorly understood. For this observational study, we recruited 17 depressed PHN patients, 19 non-depressed PHN patients, and 34 healthy controls (HCs) for resting-state functional MRI scans. We firstly investigated the differences in fractional amplitude of low-frequency fluctuation and regional homogeneity values among the three groups to identify a characteristic brain signal of pain-depression comorbidity. Abnormal voxel-wised functional connectivity was then compared across groups and correlated with clinical variables in each group. One-way analysis of covariance results revealed the fractional amplitude of low-frequency fluctuation values differences in the right temporal lobe (TL) and its voxel-wised connectivity with the inferior frontal gyrus (IFG) among three groups. Furthermore, the TL-IFG connectivity was positively associated with the positive emotional scores and life quality scores among depressed PHN patients, but not non-depressed PHN patients and HCs. In summary, these findings highlighted the TL dysfunction in pain-depression comorbidity among PHN population and may offer heuristic cues for central therapeutic targets that could disrupt the pain-depression vicious circle.