Transcranial photobiomodulation (tPBM) is a noninvasive light illumination method in which cells or tissues are exposed to low levels of 600 to 1100 nm wavelength red and near-infrared (NIR) light, containing relatively lower energy densities. Soon after the invention of the ruby laser and helium-neon laser, photobiomodulation (PBM) came as a therapeutic technique in the 1960s, which was also known as low-level laser therapy.

Mester et al. discovered the benefits of PBM in 1967 when they tried to treat malignant cancer on shaved rats with a ruby laser at low power. Various research suggests that PBM can enhance neuroprotection by modulating neurotrophic factors and inflammatory signalling molecules as well as anti-apoptotic mediators, activating ion channels, and stimulating transcription factors that up-regulate the expression levels of genes.

Some evidence also shows that tPBM might be a potential brain stimulation technique for neurological and neurodegenerative diseases such as stroke, (c) Alzheimer’s disease (AD)/dementia, (d) brain cerebral ischemia, (e) Parkinson’s disease (PD) and others.

In t-PBM, a cap delivers light waves generated by either lasers or LEDs (light-emitting diodes). The key is that the light provided be of a particular wavelength, ranging from deep red to near-infrared (about 600 to 1070 nanometers). Such light can penetrate the skull and alter underlying tissue and cell biomechanics.

Paolo Cassano, in Massachusetts General Hospital, is an innovator of t-PBM, including that delivered in the near-infrared band of the spectrum. Dr Cassano’s 2012 Investigator project lead to an experiment with NIR t-PBM. In 2015, he led a pilot randomized, controlled clinical trial using this technology to treat four patients with major depressive disorder. In 2018, he led a team in a randomized, controlled trial of t-PBM using LED technology. Both practices saw reductions in depression symptoms, encouraging further testing of t-PBM.

One thing still needs to be added, which may partly be a struggling t-PBM to get FDA approval, is the lack of research precisely testing the safety profile of t-PBM. In a new project, the team sought to figure out the tolerability and safety of t-PBM for treating major depression as well as a generalized anxiety disorder (GAD).

In research published on December 2 in the journal Science Advances, laser light therapy has been proven to be effective in improving short-term memory.

Laser light therapy could improve short-term, or working memory in people by up to 25 percent. This is according to new research done by scientists at the University of Birmingham in the UK and Beijing Normal University in China.

However, even the simplest tasks involve multiple cognitive processes, which might confound the associations between the tPBM effect and brain performance enhancement.

Author: Azadeh Mozhdehfrahbakhsh
Source:  

• Jing You, Haiyan Huang, Clement T. Y. Chan, Lin Li, Pathological Targets for Treating Temporal Lobe Epilepsy: Discoveries From Microscale to Macroscale, Frontiers in Neurology, 10.3389/fneur.2021.779558, 12, (2022).

Image: The image is credited to MIT