Anxiety Suppressed Prefrontal Cortex Brain Activity: Insights From a Large Sample of Functional Near-Infrared Spectroscopy (fNIRS) Data

Background: Anxiety is one of the most common mental disorders and is linked to alterations in prefrontal cortex (PFC) function. Research on the underlying neuroscience has significant theoretical and practical implications. This study used a more naturalistic task and a larger sample to clarify how anxiety relates to brain activity. Materials and Methods: We recruited 841 participants and grouped them by Hospital Anxiety and Depression Scale (HADS) anxiety scores into no anxiety (NA), suspected anxiety (SA), and confirmed anxiety (CA). During an emotional autobiographical memory task (EAMT), a 53-channel functional near-infrared spectroscopy (fNIRS) system measured oxyhemoglobin (Oxy-Hb). Results: Group differences were most pronounced in Channels 30 and 33 within the right frontopolar cortex (rFPC): NA and SA showed higher Oxy-Hb than CA, whereas NA and SA did not differ (p < 0.001 for NA/SA > CA). Emotional valence showed no main or interaction effects. Oxy-Hb in rFPC correlated negatively with anxiety severity (Ch30: r = −0.15, p < 0.001; Ch33: r = −0.16, p < 0.001), with similar patterns across additional channels. Conclusions: rFPC hypoactivation differentiates clinically significant anxiety from lower-symptom groups and scales with symptom severity during EAMT. Findings support fNIRS as a practical physiological index for characterizing anxiety-related prefrontal dysfunction in large samples. Future work should incorporate short-separation channels and broader diagnostic measures.