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

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.

Near infrared low‐level laser therapy and cell proliferation: The emerging role of redox sensitive signal transduction pathways

“…Photostimulation of this enzyme leads to an increase in cellular energy availability, oxygen consumption and signal transduction, along with a transient increase in ROS [53]. The macroscopic result of such stimulation is strongly dependent upon cell type, cell growth phase and associated redox conditions [3,16,18,50,54,55].…”

“…Their generation during light irradiation is very important in modulating cell responses, as it has been hypothesized the existence of 2 kinds of ROS. Low-level ROS, produced at faintly low fluences of light are mainly represented by superoxide, while high-level ROS, accounting for the more damaging effects are mainly represented by hydroxyl radicals and peroxynitrite and are generally produced when higher light fluence is delivered [4,16,21,47,51,55,61].…”

Photobiomodulation for Alzheimer’s Disease: Translating Basic Research to Clinical Application

“…As stated by Hashmi et al in their article about the role of PBM in neurorehabilitation [20], transcranial PBM with low level red to NIR light had already been used on human subjects with moderate AD before the year 2010, although no peer reviewed publications existed as of then. This is slowly changing, with new devices being developed and more individuals being treated in pilot trials, confirming improvements in the Alzheimer's Disease Assessment Scale-cognitive and enhanced Neuropsychiatric Inventory scores, as well as an increase in regional cerebral blood flow and increased connectivity of the default mode network [29,[48][49][50][51][52][53].…”

Photobiomodulation of the Visual System and Human Health

“…It has been known for some time that a fraction of long-wave light delivered through the skull can reach neurons (hence, the success of techniques such as optical neuroimaging or optogenetics) and moderate their activity. Indeed, although in inchoate stages, there is hope that transcranial PBM may be an effective treatment for Alzheimer's disease and other dementias [150] and degenerative movement disorders such as Parkinson's [151]. A "photoceutical" approach has been used in wound care for years [152] with clear evidence of its efficacy [153].…”