Table 2.
Studies on improvement of cognitive dysfunction in AD patients after transcranial photobiomodulation
| Study (year) | Mode | Wavelengths and Irradiation Parameters | Irradiation Approach and Sites | Outcomes or Findings |
|---|---|---|---|---|
| Maksimovich et al. (2015) [64] | AD patients (34.83% male and 65.17% female) without serious comorbidities |
Visible region of spectrum; 20 mw, fiber diameter of 25–100 μm, 20–40 min |
Transcatheterly | Improved cerebral microcirculation and cognitive recovery; decreased permanent dementia |
| Nichols et al. (2017) [62] | AD patients | 1064 nm, 3.4 W, 250 mW/cm2, 120 or 137.5 J/cm2 per session, CW | Transcranially | Improved reaction time and lapses in psychomotor vigilance task and correct responses in delayed match to sample task; increased resting-state EEG alpha, beta, and gamma power; |
|
Glushkovskaya et al (2019) [24] |
Mongrel male mice injected Aβ (1–42) peptide (1 μL, 200 μmol) in the CA1 field of the hippocampus bilateral |
1267 nm, 50–200 mW/cm2, 18–39 J/cm2 at brain’s surface, beam diameter of 5 mm, CW |
Transcranially; High power laser diode (LD-1267-FBG-350) |
Transcranial photobiomodulation significantly reduces the deposition of Aβ plaques (by stimulating lymphatic drainage) and improves cognition, memory and neurological status |
| Xing et al. (2020) [72] | Double transgenic mice (APPswe/PSENdE9) | 632.8 nm, 92 mW, 10 min, spot area of 0.785 cm2 in cerebral cortex and hippocampus, once a day, CW | He–Ne laser | Transcranial photobiomodulation has the ability to improve cognitive impairment in Alzheimer’s disease |
| Shin et al. (2020) [73] | Transgenic (5XFAD) male mice | 610 nm, 1.7 mW/cm2, 2.0 J/cm2, spot diameter of 4 mm onto the midpoint of the parietal bone and the posterior midline of the seventh cervical vertebra, 20 min × 3, 14 weeks | Skin-adherent LED probe | Transcranial photobiomodulation has the ability to reduce amyloid accumulation, neuronal loss and microgliosis and improve cognitive impairment by elevating insulin-degrading enzyme associated with Aβ degradation |
| Huang et al. (2021) [67] | AD patients with dementia but without serious comorbidities | 1060–1080 nm and 15,000 mW, 23.1 mW/cm2, ~ 650cm2 per treatment area, 6 min × 2 daily for 8 weeks |
Transcranially (light treatment helmet devices) |
The NIR light treatments demonstrated safety and positive cognitive improvements in AD patients with dementia, and the trial designed a simple treatment that could benefit dementia patients |