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. 2019 Sep;6(3):77.
doi: 10.3390/photonics6030077. Epub 2019 Jul 4.

Photobiomodulation for Alzheimer's Disease: Has the Light Dawned?

Michael R Hamblin  1   2   3
Affiliations

Photobiomodulation for Alzheimer's Disease: Has the Light Dawned?

Michael R Hamblin. Photonics. 2019 Sep.

Abstract

Next to cancer, Alzheimer's disease (AD) and dementia is probably the most worrying health problem facing the Western world today. A large number of clinical trials have failed to show any benefit of the tested drugs in stabilizing or reversing the steady decline in cognitive function that is suffered by dementia patients. Although the pathological features of AD consisting of beta-amyloid plaques and tau tangles are well established, considerable debate exists concerning the genetic or lifestyle factors that predispose individuals to developing dementia. Photobiomodulation (PBM) describes the therapeutic use of red or near-infrared light to stimulate healing, relieve pain and inflammation, and prevent tissue from dying. In recent years PBM has been applied for a diverse range of brain disorders, frequently applied in a non-invasive manner by shining light on the head (transcranial PBM). The present review discusses the mechanisms of action of tPBM in the brain, and summarizes studies that have used tPBM to treat animal models of AD. The results of a limited number of clinical trials that have used tPBM to treat patients with AD and dementia are discussed.

Keywords: Alzheimer’s disease; animal models; clinical trials; dementia; mechanisms of action; photobiomodulation.

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Conflict of interest statement

Conflicts of Interest: M.R.H. declares the following potential conflicts of interest. Scientific Advisory Boards: Transdermal Cap Inc., Cleveland, OH, USA; BeWell Global Inc., Wan Chai, Hong Kong; Hologenix Inc. Santa Monica, CA, USA; LumiThera Inc., Poulsbo, WA, USA; Vielight, Toronto, ON, Canada; Bright Photomedicine, Sao Paulo, Brazil; Quantum Dynamics LLC, Cambridge, MA, USA; Global Photon Inc., Bee Cave, TX, USA; Medical Coherence, Boston, MA, USA; NeuroThera, Newark, DE, USA; JOOVV Inc., Minneapolis-St. Paul, MN, USA; AIRx Medical, Pleasanton, CA, USA; FIR Industries, Inc. Ramsey, NJ, USA; UVLRx Therapeutics, Oldsmar, FL, USA; Ultralux UV Inc, Lansing, MI, USA; Illumiheal & Petthera, Shoreline, WA, USA; MB Lasertherapy, Houston, TX, USA; ARRC LED, San Clemente, CA, USA; Varuna Biomedical Corp. Incline Village, NV, USA; Niraxx Light Therapeutics, Inc., Boston, MA, USA. Consulting; Lexington Int., Boca Raton, FL, USA; USHIO Corp., Japan; Merck KGaA, Darmstadt, Germany; Philips Electronics Nederland B.V. Eindhoven, Netherlands; Johnson & Johnson Inc., Philadelphia, PA, USA; Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany. Stockholdings: Global Photon Inc., Bee Cave, TX, USA; Mitonix, Newark, DE, USA.

Figures

Figure 1.
Figure 1.
Proposed chromophores for PBM that can absorb different wavelengths of light. It should be noted that there is considerable overlap between the chromophores, and that the NIR absorbed by structured water is likely to be longer wavelength (>950 nm).
Figure 2.
Figure 2.
There are a large number of mechanisms for tPBM in the brain that have been proposed (discussed below).
Figure 3.
Figure 3.
Selection of tPBM devices that have been clinically tested in AD and other brain disorders. (A) Helmet from Photomedex Inc. (Philadelphia, PA, USA); (B) Helmet from THOR Photomedicine (Chesham, UK); (C) Lumiwave LED clusters from BioCare Systems (Parker, CO, USA); (D) Helmet from Cognitolite (Dublin, Ireland); (E) Neuro-alpha LED device from Vielight (Toronto, ON, Canada); (F) Device from ProNeuroLIGHT LLC (Phoenix, AZ, USA).
See this image and copyright information in PMC

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