The association between resting-state prefrontal network and cognitive function in depressed patients with insomnia.

To investigate the association between the resting-state prefrontal network and cognitive function in depressed patients with insomnia using functional near-infrared spectroscopy (fNIRS). This study included 37 depressed patients with insomnia (comprising 14 males and 23 females) and 49 healthy controls (comprising 21 males and 28 females). The severity of depression and anxiety was assessed using the Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder Scale-7 (GAD-7), respectively, while the Pittsburgh Sleep Quality Index (PSQI) evaluated sleep quality. Cognitive function was assessed using the Trail Making Test (TMT) and Spatial Span Test (SST). Resting-state prefrontal cortical activation and functional connectivity (FC) were analyzed based on fNIRS data. ROC curves evaluated the predictive value of combined TMT, SST, the frontopolar and orbitofrontal cortex (FPC-OFC), and the temporopolar and inferior prefrontal cortex (TPC-IPFC) metrics. The patient group had significantly higher scores on the PSQI, PHQ-9, GAD-7, and TMT, alongside lower SST scores compared to the control group. The patient group also showed significantly reduced activation levels in three frontal pole regions and one dorsolateral prefrontal cortex region. There were reduced FC in FPC-OFC and TPC-IPFC regions, with significant changes in FC across multiple channels. Additionally, FC in the FPC-OFC region was negatively correlated with TMT but positively correlated with SST. ROC analysis showed that combined TMT, SST, FPC-OFC, and TPC-IPFC metrics had the highest diagnostic accuracy. Depressed patients with insomnia show impaired prefrontal cortical function, with FPC-OFC connectivity closely linked to cognitive performance, offering imaging-based insights for rehabilitation.