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.
Future Perspectives
The fact that PBMT may produce a large range of beneficial changes in the brain, and is without any major side-effects, suggests it should be more widely tested for AD and dementia in large controlled trials. Exposing the head to light at power levels less than that received in direct sunlight (but without harmful ultraviolet wavelengths) is intrinsically safe. Any side-effects reported have been rare, mild and transient, consisting of slight headache, difficult sleeping and mild itching on the scalp. It is likely that tPBM for AD will need to be continued indefinitely, as regressions have been observed when PBM treatments have ceased. Moreover, unrelated health problems such as urinary tract infections or falls can lead to loss of the benefits achieved with tPBM. Home use tPBM devices can be applied by the caregivers, who consistently report improvements in their own quality of life.
