Brain photobiomodulation (PBM) is the use of near-infrared (NIR) energy to improve cognitive functions and mental acuity. This bioenergetics process stimulates the photosensitive cytochrome c oxidase enzyme within mitochondria to produce more ATP (adenosine triphosphate). For example, this is similar to the conversion of nutrients from food into metabolic energy but with photons as the energy source. Additionally, photobiomodulation enhances nitric oxide synthesis, resulting in vasodilation and increased cerebral blood flow.

The therapeutic effects of brain photobiomodulation therapy are enhanced oxygenation[1], brain energy metabolism[2], neuronal protection[3] and neurogenesis[4]. What’s great is, these benefits trigger an increase in mental acuity and brain health without negative side effects or use of artificial chemicals. If you’d like to learn more about the penetration of NIR light through the skull, this article covers that topic.

Independent research in the field of brain photobiomodulation using Vielight technology has demonstrated efficacy in a wide range of applications. Here are some examples: Independent research demonstrated neural oscillation modulation through brain photobiomodulation. Moreover, pre-clinical research by the University of California San Francisco on dementia patients showed that cerebral blood flow and neural connectivity could be enhanced through brain PBM. Lastly, researchers at the Veterans Affairs Boston Healthcare System are investigating the efficacy of brain photobiomodulation to treat gulf war illness. To read more on additional ongoing and publish research in human trials, this page has a list of studies.

Mechanisms

Figure 1. Mechanism of photobiomodulation therapy in mitochondria[5]

A) Photobiomodulation stimulates cytochrome c oxidase, which increases ATP synthesis. This results in the enhancement of neuronal respiration and metabolism.
B) Photobiomodulation dissociates nitric oxide from the center, increasing the proton gradient.

Brain Bioenergetics

Brain photobiomodulation has an enhancing effect on neuronal mitochondria without any negative side effects or harmful chemicals. Additionally, brain disorders are commonly caused by mitochondrial dysfunction[6] because brain tissue is rich in mitochondria[7].

Results from a study on human neuronal cells (808 nm) reveals that maximum ATP production occurred at 10 minutes post-irradiation.[8] Also, another study[9] using phosphorus magnetic resonance spectroscopy (MRS) evaluated the metabolic rate in neurons following transcranial laser therapy (808 nm). Correspondingly, repeated irradiation over 2 weeks showed prolonged beneficial effects and improved cerebral bioenergetics.

Neural Oscillations

The discovery of the effect of brain photobiomodulation PBM on neural activities and brain oscillations is groundbreaking. In this cross-over, double-blind study, the results revealed a significant effect of transcranial near-infrared light (810 nm wavelength) at a 40 Hz pulsing rate. The effects were on the power, functional connectivity and synchronization of endogenous brain activity.

The potential of brain PBM to modulate brain activity opens new opportunities for research and therapy. In a published study, delivering NIR light energy pulsed at 40 Hz to the hubs of the default mode network significantly increases the power of the high oscillatory frequencies of alpha, beta and gamma. Ultimately, this points towards the potential of brain PBM to improve focus and memory encoding.

Cerebral Blood Flow

Blood flow to the brain is vital – neurons need oxygen to function properly. Inadequate blood flow to the brain has been linked to several dysfunctions, such as depression and anxiety. According to pre-clinical findings, PBM could potentially increase nitric oxide in neurons, which leads to an increase in cerebral blood flow[10]. Furthermore, in the most recent clinical investigations by the University of Texas, improvement in cerebral oxygenation was found both during and following transcranial laser irradiation.[11]

Clinical research using Vielight technology by the University of California San Francisco on people with dementia has shown that brain photobiomodulation can increase cerebral blood flow, leading to an overall increase in their cognitive function.

Neuroinflammation

Neuroinflammation is inflammation of brain tissue which is mediated by microglial cells. Microglial cells respond to neuronal damage by releasing pro-inflammatory markers (cytokines). Inflammatory cytokines play a role in initiating the inflammatory response. Dysregulation of proinflammatory cytokines has been linked to depression and other neurological diseases.

In an early study[12], researchers assessed the anti-inflammatory effects of NIR lasers on the alteration of cerebral interleukins in cryogenic brain injury and found a decreased level at 24 hours compared to 6 hours. Moreover, brain photobiomodulation activated cellular immunity via increasing the presence of interleukins in blood cells at 20 days post-stroke.

These studies supports the idea that the anti-inflammatory effects of brain PBM may be due to its ability to modulate microglial activity.

Neurogenesis

Increased expression of neurotrophins may account for observations of stimulation of neurogenesis.[13] The neurogenesis effects of PBM was demonstrated in TBI mice models.[14] In a series of studies, researchers determined the optimal regimen of transcranial PBM (810 nm) for neuroprotection in TBI mice, and reported that PBM for 1 to 3 consecutive days notably stimulated neurogenesis.

Conclusion

Because neural tissues contain large amounts of mitochondrial cytochrome c oxidase, brain photobiomodulation has great potential. Improving mental acuity through enhanced cerebral metabolic function and blood flow, stimulating neurogenesis and providing neuroprotection are the most important effects of brain PBM therapy.

Figure 2 Beneficial effects of brain photobiomodulation
Source : Mol Neurobiol. 2018 Aug; 55(8): 6601–6636

References

  1. Rojas JC, Bruchey AK, Gonzalez-Lima F. Low-level light therapy improves cortical metabolic capacity and memory retention. J Alzheimers Dis. 2012;32(3):741–752
  2. Lu Y, Wang R, Dong Y, Tucker D, Zhao N, Ahmed ME, Zhu L, Liu TC-Y, Cohen RM, Zhang Q. Low-level laser therapy for beta amyloid toxicity in rat hippocampus. Neurobiol Aging. 2017;49:165–182
  3. Quirk BJ, Torbey M, Buchmann E, Verma S, Whelan HT. Near-infrared photobiomodulation in an animal model of traumatic brain injury: improvements at the behavioral and biochemical levels. Photomed Laser Surg. 2012;30(9):523–529
  4. Xuan W, Agrawal T, Huang L, Gupta GK, Hamblin MR. Low-level laser therapy for traumatic brain injury in mice increases brain derived neurotrophic factor (BDNF) and synaptogenesis. J Biophotonics. 2015;8(6):502–511
  5. Mattson MP, Gleichmann M, Cheng A. Mitochondria in neuroplasticity and neurological disorders. 2008;60(5):748–766.
  6. Passarella S, Karu T. Absorption of monochromatic and narrow band radiation in the visible and near IR by both mitochondrial and non-mitochondrial photoacceptors results in photobiomodulation. J Photochem Photobiol B, Biol. 2014;140:344–358
  7. Schwarz TL. Mitochondrial trafficking in neurons. Cold Spring Harb Perspect Biol. 2013;5(6):a011304.
  8. Oron U, Ilic S, De Taboada L, Streeter J. Ga-As (808 nm) laser irradiation enhances ATP production in human neuronal cells in culture. Photomed Laser Surg. 2007;25(3):180–182.
  9. Mintzopoulos D, Gillis TE, Tedford CE, Kaufman MJ. Effects of Near-Infrared Light on Cerebral Bioenergetics Measured with Phosphorus Magnetic Resonance Spectroscopy. Photomed Laser Surg. 2017;35(8):395–400
  10. Uozumi Y, Nawashiro H, Sato S, Kawauchi S, Shima K, Kikuchi M. Targeted increase in cerebral blood flow by transcranial near-infrared laser irradiation. Lasers Surg Med. 2010;42(6):566–576.
  11. Wang X, Tian F, Reddy DD, Nalawade SS, Barrett DW, Gonzalez-Lima F, Liu H. Up-regulation of cerebral cytochrome-c-oxidase and hemodynamics by transcranial infrared laser stimulation: A broadband near-infrared spectroscopy study. J Cereb Blood Flow Metab. 2017;37(12):3789–3802.
  12. Moreira MS, Velasco IT, Ferreira LS, Ariga SKK, Barbeiro DF, Meneguzzo DT, Abatepaulo F, Marques MM. Effect of phototherapy with low intensity laser on local and systemic immunomodulation following focal brain damage in rat. J Photochem Photobiol B, Biol. 2009;97(3):145–151.
  13. Telerman A, Lapter S, Sharabi A, Zinger H, Mozes E. Induction of hippocampal neurogenesis by a tolerogenic peptide that ameliorates lupus manifestations. J Neuroimmunol. 2011;232(1):151–157.
  14. Xuan W, Vatansever F, Huang L, Wu Q, Xuan Y, Dai T, Ando T, Xu T, Huang Y-Y, Hamblin MR. Transcranial low-level laser therapy improves neurological performance in traumatic brain injury in mice: effect of treatment repetition regimen. PLoS One. 2013;8(1):e53454.