Young Adults with Anxiety Disorders Show Reduced Inhibition in the Dorsolateral Prefrontal Cortex at Higher Trait Anxiety Levels: A TMS-EEG Study

Background. The neuropathology of anxiety disorders, including specific phobias, social phobias, and generalized anxiety disorders (GAD), has been believed to be rooted in a reduced inhibition of limbic areas by the dorsolateral prefrontal cortex (DLPFC). Trait anxiety has been linked to insufficient recruitment of DLPFC mechanisms for attentional control. Despite limited research on individuals with anxiety disorders, our study utilized transcranial magnetic stimulation to assess DLPFC cortical activity and emotional states using the N100 as an indicator of GABA-B-mediated cortical inhibition. Additionally, we aimed to correlate trait anxiety scores with cortical activity. Methods. A total of 20 subjects with social phobia and GAD and 21 subjects with specific phobia were compared to 24 control subjects regarding their inhibitory N100 in the DLPFC. Therefore, TMS was applied on the left and right DLPFC during an emotional task with fearful, angry, and neutral faces and a rest condition. Results. Smaller N100 amplitudes after DLPFC stimulation were found in subjects with social phobia, GAD, and social phobias compared to the control group. Furthermore, a correlation between trait anxiety scores and smaller N100 amplitudes, independent of group effects, was found. Conclusion. There appears to be a decrease in GABA-B-mediated cortical inhibition in the DLPFC in subjects with anxiety disorders. The correlation between trait anxiety and N100 amplitudes suggests a trait-related modulation of cortical inhibition.