Figure 4.

Use of fNIRS to Monitor Treatment Response Across Psychiatric Disorders. (A) Heatmap showing the number of studies employing fNIRS across different psychiatric diagnoses and intervention types. Most research has focused on MDD, schizophrenia, and anxiety disorders, particularly in conjunction with rTMS/iTBS and pharmacological interventions. (B) Sankey diagram illustrating the flow from diagnosis to intervention and reported clinical outcomes. The majority of studies report positive fNIRS-clinical correlations, though representation varies across disorders. Gaps in combined or VR-based therapies suggest potential avenues for future research.