Attenuated Motor Cortical Responsiveness to Motor and Cognitive Tasks in Generalized Anxiety DisorderAuthor(s): Cheng-Ta Li , Chia-Feng Lu, Yu-Te Wu, Szu-Hui Lee, Ruei-Wen Chu, Tung-Ping Su
Generalized anxiety disorder (GAD) is characterized by excessive and uncontrollable worries. Recent research revealed impaired intracortical facilitation of bilateral motor cortices (M1) in GAD. Therefore, we aimed to elucidate whether M1 cortical activations could be a reliable and clinically-feasible biomarker for GAD. Forty GAD patients and twenty healthy control subjects were recruited. Bilateral M1 cortical activations in response to 4 different tasks, including finger tapping (FT), verbal fluency test (VFT), dual tasks with simultaneous FT and VFT (DT), and DT with pretreated pressure to enhance worries (DTp), were measured by multichannel functional near-infrared spectroscopy (fNIRS). Task-induced total hemoglobin changes (Δ [Hb]) were used as the index of cortical activations. The quantitative Δ [Hb] results revealed that GAD had abnormally decreased Δ [Hb] over bilateral M1. Repeated-measure ANCOVA revealed a significant main effect of group on bilateral M1 Δ [Hb] results (left M1: F=11.026, p=0.002; right M1: F=9.843, p=0.003), indicating that GAD had significantly lowered M1 Δ [Hb] across all tasks. The ROC analysis revealed that M1 Δ [Hb] in response to VFT demonstrated good sensitivity/specificity in predicting a diagnosis of GAD. In conclusion, attenuated M1 cortical responsiveness to motor and cognitive tasks as a characteristic feature of GAD could have the diagnostic value in clinically settings.