Anxiety disorders, especially Generalized Anxiety Disorder (GAD), can severely impact quality of life and remain a challenge in mental health treatment. A recent study explored a non-invasive, light-based approach to address this issue — using transcranial near-infrared stimulation (tNIRS) to target a key brain region involved in emotional regulation.
The Intervention: 820-nm tNIRS Applied to the Left DLPFC
In a randomized, double-blind, sham-controlled study, 36 patients diagnosed with GAD were enrolled. Half received active tNIRS treatment and the other half received sham stimulation. The protocol used a continuous laser beam with a wavelength of 820 nm and 310 mW/cm² of power, applied to the left dorsolateral prefrontal cortex (DLPFC) — a region associated with executive functions and emotional processing.
Treatment sessions were delivered over 14 consecutive days, with four sessions of 4 minutes each per day, separated by 5-minute intervals. The total light energy that reached the cortex was calculated at 10.4 J. During the sessions, patients wore protective eyewear and the laser device was precisely positioned on the scalp according to EEG-based anatomical markers (point F5).
Key Results: Anxiety Relief and Neural Modulation
- Anxiety symptoms, as measured by the Hamilton Anxiety Rating Scale (HAMA), significantly decreased in the active group — both immediately after treatment and during follow-ups at 2, 4, and 8 weeks.
- Although depressive symptoms (HAMD scale) did not show significant differences between groups, greater improvement was seen in the active tNIRS group.
- Sleep quality (PSQI) improved in the active group after 4 and 8 weeks, though the difference between groups was not statistically significant.
- Brain network analysis revealed enhanced information outflow from the left DLPFC and left posterior temporal region in the active group.
- No serious adverse events were reported. One patient developed bacterial conjunctivitis (not treatment-related), and another reported mild temporary temple pain.
Authors’ Conclusions
According to the study, tNIRS at 820 nm targeting the left DLPFC effectively alleviates anxiety symptoms in patients with GAD, with effects lasting for at least two months. Additionally, changes in EEG brain network patterns suggest that this stimulation may support fronto-temporal brain connectivity, contributing to its therapeutic effects.
Reference: Wang H, Song P, Hou Y, Liu J, Hao W, Hu S, Dai X, Zhan S, Li N, Peng M, Wang H, Lin H, Wang Y. 820-nm Transcranial near-infrared stimulation on the left DLPFC relieved anxiety: A randomized, double-blind, sham-controlled study. Brain Res Bull. 2023; 200:110682. doi: 10.1016/j.brainresbull.2023.110682.