For example, in amyloid precursor protein/presenilin 1 (APP/PS1) transgenic mice (an Alzheimer’s disease (AD)-like mouse model), the application of PBM (peak wavelength 7.7–10 μm) for six weeks reversed the gut microbiota composition in the APP/PS1 mice, suggesting that the positive effect of PBM for AD treatment is likely via the brain-gut axis [107]. Here, PSEN1 is linked to Alzheimer disease.