Life becomes more interesting as new ways of doing things emerge. Every passing day brings us closer to the pinnacle of our civilization, but some of these technological advancements make it difficult to determine whether something is truly awesome, mediocre, or dangerous. As photobiologically active beings, light does more than just enabling us to see. It influences and/or alters biological activity, significantly, if focused strategically. Here is an example of such significant effects of strategically focused light: Transcranial Infrared Laser Stimulation (TILS), a modern technique that stimulates brain function by exposing lasers through the forehead. So, ideally, using light from a specific laser can influence brain activity, resulting in the improvement of cognitive function, alteration of mood and emotions, and the increase in certain response rates. A stoner is already excited, I know! But first, let’s take a closer look to understand what’s going on.
ABOUT TRANSCRANIAL INFRARED LASER STIMULATION
Physiologically in our bodies, all cells need energy to perform their different functions. The energy requirement of the cells depends on their level of function and similarly their level of function is influenced and limited by the amount of energy available at any given time. This energy is acquired from the oxygen we breath, but our cells do not use the oxygen directly as a source of energy. An important enzyme called cytochrome-c-oxidase (CcO, or COX), alongside other factors, is responsible for oxygen consumption in the cells, which in turn initiates processes involving four other enzymes that eventually produce the primary source of energy, Adenosine Triphosphate (ATP), which is the primary fuel for every cell (Kadenbach 2018). Hence both the oxygen and the enzymes involved in the production of ATP are vital components for every cell’s functional capacity.
Thus, TILS is a form of photobiomudulation (PBM), which uses longer wavelengths of laser light preferably in the red or near infrared region (NIR) to stimulate the functional ability of the brain (Holmes et al. 2019). To achieve this, laser light is irradiated onto the forehead and the waves penetrate through the forehead to reach brain tissue. When the photons of light hit the brain tissue, they make the CcO enzyme more functional and concurrently the flow of blood increases leading to more oxygen available for use. Hence, when the activity of CcO is increased and oxygen is available abundantly, more ATP will be produced, and there will be more fuel for brain cells to perform their function (Wang et al. 2017, Holmes et al. 2019). Thus far, the beneficial effects of using TILS have been reported in many practical cases, and measures of brain activity e.g., psychomotor vigilance task (PVT) and delayed match-to-sample (DMS) memory task (i.e., measures that reflect the speed and accuracy of cognitive processing) have proven this association. (Barret and Gonzalez-Lima 2013, Hwang et al. 2016, Caldieraro and Cassano 2019, Holmes et al. 2019).
WHAT ARE THE POSSIBLE IMPLICATIONS ON HEALTH AND SOCIETY?
Getting enough light energy to pass through the entire thickness of the frontal bone into the brain tissue is the main dilemma. According to Barrett and Gonzalez-Lima (2013) only 1–2% of the laser light applied to the forehead at near infrared wavelengths passes through the frontal bone. That’s why higher fluencies and longer wavelengths should be used to achieve a measurable outcome. The thickness of the skull bone ranges from 5 – 9 mm in most adults (Mahinda and Murty 2009), and thus far the largest penetration distance through the skull was assessed at 30 mm using a lamb cadaver skull tissue and the results showed that 15 Watts of a 810 nm and 980 nm (Diowave) devices in continuous (non-pulsed) NIR laser penetrated 30 mm to deliver about 2.9% and 1.22% respectively energy at a 30 mm distance deep tissue (Henderson and Morries, 2015).
In humans 0.85% of light can pass through an entire hand with a thickness of 30 mm. Moreover, there are significant differences in light transmission between living tissue and post-mortem tissue due to many reasons including the state and flow of blood, cross-linking of proteins, changes in interstitial fluids etc, making living tissue more permeable to light in the red and NIR regions (Henderson and Morries, 2015), and that may explain why TILS have a measurable effect on brain function. Hence, TILS does sounds like a marijuana analogue! It enhances cognitive function, alters one’s mood and emotions, and influences brain activity measured and confirmed by PVT and DMS memory task scales. How different is it from most drugs used for recreational purposes? Recreational drugs influence brain activity, alter moods and emotions, and alter brain response rates, etc. Should we call TILS a recreational laser therapy? If so, what are the implications on health and society? Or what could possibly go wrong? Think about the following questions:
- Will cognitive enhancement using TILS be legal? Can students be allowed to photobiomodulate before a big test, and will that be a fair exam? Or if it becomes legal, will it not be another socioeconomic disparity where rich kids have access to cognitive enhancement and less fortunate ones don’t?
- What level of regulation will be required to facilitate the use of TILS? Who will regulate it? Can we have these lasers at home? What are the possible long-term psychological effects of use? Addictions, dependence maybe?
- What is the acceptable dose, frequency, or limits. How much is too much? And because larger doses are used to achieve penetration, what happens to the larger percentage of light that’s absorbed by the skull bone? So many stem cells in there! Besides, some research has shown that certain channels between the skull bone marrow and the brain, constitute a migratory path for inflammatory neutrophils produced that can actually damage the brain (Mcgreevey 2018). Are we not photobiomodulating those? With this and other unstudied interactions, shouldn’t we be worried about causing brain injuries in the long term?
HERE’S WHERE WE LEAVE IT!
Though the mechanisms of action have been studied quite significantly, the extended consequences of TILS on the brain remain understudied and the questions above remain unanswered. However, the beneficial effects are overwhelming, from treatment of mood ailments to more serious psychological disorders and neurodegenerative diseases. What we may need is more exploratory research, proper regulation when it comes to leisure usage and try to answer the uncertain biological and societal impacts of such a practice. Best case scenario however, we could have a more legal recreational therapy to use. Shout out to science!
LEAVE YOUR COMMENTS, WE WANT TO HEAR YOUR THOUGHTS!
This is very interesting. At what stage of investigation is this technology? Any clinical trials?