Conclusion
This comprehensive review of photobiomodulation (PBM) research reveals several critical findings that significantly impact our understanding of its therapeutic application in neurological conditions. The evidence demonstrates that the efficacy of PBM therapy is fundamentally dependent on achieving adequate light penetration to reach target brain tissues with sufficient energy to trigger therapeutic mechanisms.
Key conclusions include:
Penetration Requirements:
High-powered NIR lasers (10-15W) are necessary to deliver therapeutic fluence to deeper brain structures
Low-power LED devices (<1W) show insufficient penetration through human tissue
Optimal wavelengths of 810nm and 980nm, combined with appropriate power levels, can achieve therapeutic depths of 3cm or more
Clinical Efficacy:
High-powered PBM demonstrates robust clinical outcomes with 92% response rates
Benefits often appear within four treatments and can persist for up to 55 months
Treatment shows particular promise for conditions like TBI-associated depression
The therapy demonstrates an excellent safety profile with minimal, transient side effects
Treatment Parameters:
Surface fluence of 55-81 J/cm² required for adequate penetration
Therapeutic fluence of 0.8-2.4 J/cm² needed at target depth
Treatment protocols of 8-34 sessions show optimal results
Pulsed applications may enhance penetration compared to continuous wave delivery
