Study of transcranial photobiomodulation at 945-nm wavelength: anxiety and depression.

Transcranial photobiomodulation is an innovative method for the stimulation of neural activity which consists of the exposure of neural tissue to low-level light irradiance. In the present study, light-emitting diodes (LEDs) were used as light source due to their practicality and low cost. The objective was to analyze the effects of transcranial photobiomodulation using 945-nm LED in university students with anxiety and depression. Sample was composed of 22 individuals (17-25 years of age) divided into 2 groups of 11. LED group was treated with 945-nm LEDs for 1 min and 25 s (9.35 J/cm2), while in the placebo group, the device was off when placed in contact with the frontal bone for the same amount of time as in treatment group. Participants were evaluated at baseline and after 30 days with the hospital anxiety and depression scale (HADS), the faces test, the designs test, and the grip strength test. On the HADS for anxiety, the mean PAB, PAA, PhAB, and PhAA were 13.89 ± 3.55, 12.82 ± 3.18, 10.75 ± 2.49, and 6.66 ± 2.50 points, respectively. In the HADS for depression, the mean for the PDB group was 13.89 ± 3.55 points, in the PhDB group 12.82 ± 3.18 points, in the PDA group 10.75 ± 2.49 points, and in the PhDA group 6.66 ± 2.50 points. In the PA and PD groups, mean values of 8.0 ± 1.5 and 8.9 ± 1.26 scores were obtained, but did not reach significance; however, between PA and PhD analysis, a significance level of p = 0.0003 was obtained. The 945-nm LED transcranial photobiomodulation improves brain activity and may clinically decrease anxiety and depression.

Transcranial LED therapy on amyloid-ß toxin 25-35 in the hippocampal region of rats.

Excessive Aß deposition in the brain is associated with the formation of senile plaques, and their diffuse distribution is related to Alzheimer's disease. Thirty rats (EG) were irradiated with light-emitting diode (photobiomodulation (PBM)) in the frontal region of the skull after being inoculated with the Aß toxin in the hippocampus; 30 rats were used as the control group (CG). The analysis was conducted at 7, 14, and 21 days after irradiation. We observed a decreased in Aß deposits in treated animals compared with animals in the CG. The behavioral and motor assessment revealed that the EG group covered a larger ground distance and explored the open field than the CG group on days 14 and 21 (p < 0.05). The EG group was statistically significant in the spatial memory test compared to the CG group on day 14. The use of PBM significantly reduced the presence of Aß plaques and improved spatial memory and behavioral and motor skills in treated animals on day 21.