Dose-effect relationships for PBM in the treatment of Alzheimer's disease

Alzheimer's disease (AD) has become one of the most worrying health conditions with no effective treatment available with the increase in population aging. A large number of clinical studies and experiments proved that photobiomodulation (PBM) had a positive effect on AD treatment. The irradiation with red and near-infrared light at a low dose can effectively reduce an accumulation of amyloid-β (Aβ) plaques in the central nervous system, relieving the symptoms of AD. This review summarizes the parameters of PBM for AD treatment studied on cells, animals, and in clinical trials, as well as the dose-effect relationship of PBM treatment for AD. The mechanisms of PBM on the cellular level, which include regulation of microglia and astrocytes that may affect Aβ plaque elimination are also discussed.