Highlights
- In a study of healthy older women, transcranial LED light therapy was linked to increases in brain blood-flow speed in specific arteries.
- The clearest changes were seen in the left middle cerebral artery and the basilar artery.
- Measures of vascular resistance decreased, suggesting blood vessels may have been functioning more efficiently during the assessment.
- Systemic blood pressure did not change, indicating the effect was not simply due to overall blood-pressure shifts.
- The sessions were described as non-invasive and well tolerated.
Why this matters
Healthy brain aging depends in part on steady delivery of oxygen and nutrients through cerebral blood flow. Because of this, non-invasive approaches that may support brain circulation are being actively explored. Transcranial photobiomodulation uses visible red light delivered through the scalp to influence brain-related physiology.
What the participants did (simple overview)
Healthy elderly women received transcranial LED light therapy using red light:
- Wavelength: 627 nm
- Dose: 10 J/cm²
- Light applied to four points over the frontal and parietal scalp
- 30 seconds per point (about 2 minutes per session)
- Two sessions/week for 4 weeks (14 sessions total)
- Standard safety procedures were used (head support, eye protection, consistent session timing).
Key findings:
After the intervention period, researchers observed:
- Higher blood-flow velocity in:
- the left middle cerebral artery, and
- the basilar artery
- Lower resistance index, a common ultrasound marker interpreted as reduced vascular resistance / improved vessel compliance
- No meaningful change in systemic blood pressure
- No significant change in the right middle cerebral artery (one proposed explanation was hemispheric dominance, but this remains speculative).
Takeaway
This study suggests that short, repeated sessions of transcranial red LED therapy may modulate cerebral hemodynamics — increasing blood-flow velocity in key vessels and reducing vascular resistance — without affecting overall blood pressure. While larger and more standardized trials are still needed, these results support continued research into photobiomodulation as a non-invasive, wellness-oriented approach relevant to brain aging.
Reference: Salgado, A. S., Zângaro, R. A., Parreira, R. B., & Kerppers, I. I. (2015). The effects of transcranial LED therapy (TCLT) on cerebral blood flow in the elderly women. Lasers in medical science, 30(1), 339–346. https://doi.org/10.1007/s10103-014-1669-2