A New Frontier in Brain Health: The Science of Photobiomodulation
- David Priede, MIS, PhD
- Aug 26
- 14 min read
Updated: Sep 22
Table of Contents
Introduction
In a world facing growing challenges like cognitive decline and traumatic brain injuries, the search for effective, non-pharmaceutical solutions is more pressing than ever. Photobiomodulation is moving from a niche concept to a scientifically validated tool for cognitive support, with specific consumer technologies now undergoing rigorous clinical trials.
A growing body of scientific research supports the idea of using light to influence brain function. This technology, known as transcranial photobiomodulation (tPBM), involves applying red and near-infrared light to the scalp to stimulate the brain. Initially met with skepticism, tPBM is now supported by compelling peer-reviewed studies that reveal its mechanisms and benefits.
The Core Mechanism: How Can Light Affect Your Brain?
The primary question is a physical one: how does light penetrate the skull to produce a meaningful effect? The light must be at the right wavelength (typically in the 600-1100 nm range) and delivered with sufficient power density, or irradiance, to penetrate the skin, skull, and cerebrospinal fluid to reach the brain's cortical layers (Hamblin, 2018).
This process is called photobiomodulation (PBM). Here's how it works at a cellular level:
Energizing Cellular Powerhouses (Mitochondria): Near-infrared light (often in the 810 nm wavelength range) is absorbed by an enzyme within our cells' mitochondria called Cytochrome C Oxidase. Stimulating this enzyme boosts the production of ATP (adenosine triphosphate), the primary energy currency of all cells, especially energy-hungry neurons. As we age, ATP production in the brain naturally declines; PBM appears to help counteract this by improving mitochondrial function (de Freitas & Hamblin, 2016).
Improving Blood Flow (Vasodilation): The light also stimulates the local release of nitric oxide, a molecule that relaxes the inner muscles of blood vessels, causing them to widen. This process, known as vasodilation, increases cerebral blood flow (CBF). For the brain, this is hugely significant. Better blood flow delivers more oxygen and nutrients to brain cells and helps clear metabolic waste (Naeser et al., 2014).
In essence, PBM acts as a dual-support system: it helps neurons produce more energy and improves the supply chain that delivers fuel and removes waste.
Expanded Mechanisms of Action: Beyond ATP and Blood Flow
Beyond its well-established roles in enhancing cellular energy production and cerebral blood flow, recent research has unveiled a more intricate network of mechanisms through which photobiomodulation exerts its beneficial effects on brain health. These expanded understandings highlight PBM's multifaceted impact at the cellular and molecular levels, contributing to its therapeutic potential across a range of neurological conditions.
Anti-inflammatory Effects
Chronic neuroinflammation is a significant contributor to various neurodegenerative diseases and brain injuries. PBM has demonstrated potent anti-inflammatory properties by modulating key inflammatory pathways. Studies indicate that PBM can influence the expression of pro-inflammatory and anti-inflammatory cytokines, shifting the balance towards a less inflammatory environment (Yang et al., 2018).
For instance, PBM has been shown to facilitate a phenotypic switch in microglia, the brain's resident immune cells, from a pro-inflammatory M1 state to a neuroprotective M2 state. This modulation is crucial in mitigating inflammatory damage and promoting tissue repair within the brain (Lim & Kim, 2023). The precise mechanisms involve complex interactions with signaling pathways, including NF-κB, which plays a central role in regulating immune responses and inflammation (Salehpour & Mahmoudi, 2024). By dampening excessive inflammatory responses, PBM helps to create a more conducive environment for neuronal survival and function.
Neurogenesis and Synaptogenesis
One of the most exciting discoveries in PBM research is its capacity to promote neurogenesis—the formation of new neurons—and synaptogenesis—the creation of new synaptic connections between neurons. These processes are fundamental for brain plasticity, learning, and memory. PBM has been shown to upregulate the expression of brain-derived neurotrophic factor (BDNF), a crucial protein that supports the survival of existing neurons and encourages the growth and differentiation of new neurons and synapses (Tu et al., 2023). This enhancement of neural plasticity suggests that PBM may not only protect existing brain structures but also actively contribute to the regeneration and reorganization of neural circuits, offering a pathway for functional recovery and cognitive enhancement (Nairuz & Lee, 2024).
Reduction of Oxidative Stress
Oxidative stress, characterized by an imbalance between the production of reactive oxygen species (ROS) and the body's ability to detoxify them, is a major factor in neuronal damage and aging. PBM has been found to reduce oxidative stress by enhancing the activity of antioxidant enzymes and directly scavenging ROS (Yang et al., 2020). This protective effect helps to preserve mitochondrial integrity and function, preventing the cascade of events that can lead to cellular dysfunction and death. By mitigating oxidative damage, PBM contributes to the overall resilience and longevity of brain cells.
Neuroprotection
The cumulative effects of PBM's mechanisms—improved mitochondrial function, enhanced blood flow, reduced inflammation, neurogenesis, and decreased oxidative stress—converge to provide significant neuroprotective benefits. This neuroprotection extends to various forms of brain insult, including traumatic brain injury, stroke, and neurodegenerative conditions. PBM helps to maintain neuronal viability, reduce neuronal apoptosis (programmed cell death), and preserve neurological function in the face of adverse events (Gordon & Johnstone, 2019). The ability of PBM to protect brain tissue from damage and support its recovery underscores its potential as a therapeutic intervention for a wide array of brain disorders.
From Theory to Reality: Measuring the Effects
Skepticism about PBM has faded as research has demonstrated its tangible effects on brain physiology. Studies using advanced imaging and measurement techniques have shown that effective PBM devices can:
Modulate Brainwaves: A double-blind, randomized controlled trial using a Vielight device demonstrated that PBM can significantly alter brainwave patterns on EEG readings. It was shown to increase the power of higher-frequency brainwaves (alpha, beta, gamma) associated with focus, while suppressing slower bands (delta, theta) (Zomorrodi et al., 2019). Further research has shown that tPBM can modify the brain's "microstates"—elemental blocks of neural activity—suggesting an impact on the fundamental patterns of brain function (Zomorrodi et al., 2021).
Improve Brain Connectivity: Functional connectivity analysis has shown that PBM can lead to improved integration and efficiency across multiple brain networks, suggesting more coordinated brain function after treatment sessions (Cassano et al., 2019). Studies specifically targeting the Default Mode Network (DMN) have shown increased connectivity after PBM, which is significant as this network is implicated in memory, self-reflection, and creativity (Saltmarche et al., 2017).
Clinical Applications: Where the Science is Leading
The potential of this technology lies in its application to some of the most challenging brain health issues, with specific devices now being tested in major clinical trials.
Mild Cognitive Impairment (MCI) & Dementia: A pilot study with participants in the early stages of dementia found that regular PBM treatment with a Vielight device resulted in statistically significant improvements in executive function, clock drawing, and memory recall (Saltmarche et al., 2017). A follow-up pilot trial by Chao et al. confirmed these findings, showing improved cognitive function, behavior, and increased cerebral blood flow in patients with dementia (Chao, 2019). This promising research has led to a large-scale, Phase III pivotal trial to test the Vielight Neuro RX Gamma device for FDA approval as a treatment for Alzheimer's Disease.
Traumatic Brain Injury (TBI): Multiple studies on individuals with chronic TBI have shown that PBM treatment can improve cognitive function, sleep, and mood while reducing symptoms of depression and anxiety (Naeser et al., 2014; Hamblin, 2016). A 2024 study from the University of Utah on former athletes with repetitive head impacts found that using the Vielight Neuro Gamma device not only improved cognitive scores but also led to significant gains in neuromuscular function, including reaction time, balance, and grip strength (Weiner et al., 2024).
PTSD and Mental Health: A study with military veterans suffering from chronic TBI and PTSD found that home-based PBM treatment led to meaningful improvements in sleep quality, mood, and core PTSD symptoms like hypervigilance and emotional detachment. These effects are likely tied to improved energy metabolism and blood flow in the prefrontal cortex, which is heavily involved in emotional regulation (Chao, 2019).
Broader Clinical Applications and Emerging Areas
While the document effectively highlights key clinical applications of PBM in brain health, the scope of its therapeutic potential extends to a broader array of neurological and psychiatric conditions. Ongoing research is continuously uncovering new avenues where PBM could offer significant benefits, solidifying its position as a versatile non-pharmacological intervention.
Parkinson's Disease
Parkinson's disease (PD) is a progressive neurodegenerative disorder primarily affecting dopamine-producing neurons in the brain. Preclinical and early clinical studies suggest that PBM may offer neuroprotective effects in PD by improving mitochondrial function, reducing oxidative stress, and mitigating neuroinflammation, all of which are implicated in the pathogenesis of the disease. PBM has shown promise in animal models by preserving dopaminergic neurons and improving motor function. While human trials are still in early stages, the potential for PBM to slow disease progression or alleviate symptoms in PD patients is an active area of investigation (Salehpour & Mahmoudi, 2025).
Stroke Recovery
Ischemic stroke leads to a cascade of events including energy depletion, oxidative stress, and inflammation, resulting in neuronal death and functional deficits. PBM has emerged as a promising intervention for stroke recovery due to its ability to enhance cerebral blood flow, reduce excitotoxicity, and promote neurogenesis and angiogenesis (formation of new blood vessels) in the ischemic penumbra—the area surrounding the core infarct that is at risk but potentially salvageable. Studies have demonstrated that PBM can improve neurological outcomes and functional recovery in animal models of stroke, and early human trials are exploring its efficacy in acute and chronic stroke patients (Al-Mubarak & Al-Mubarak, 2024).
Major Depressive Disorder and Anxiety Disorders
Beyond PTSD, PBM is being investigated as a potential treatment for major depressive disorder (MDD) and generalized anxiety disorder. The mechanisms underlying these effects are thought to involve improved neuronal metabolism, modulation of brain networks implicated in mood regulation (such as the default mode network and executive control network), and reduction of neuroinflammation. Clinical trials have shown promising results, with some studies indicating significant reductions in depressive symptoms and anxiety levels following PBM treatment, often with a favorable side effect profile compared to conventional pharmacotherapies (Cassano et al., 2016).
Cognitive Enhancement in Healthy Individuals
While much of the research focuses on therapeutic applications, there is also growing interest in PBM's potential for cognitive enhancement in healthy individuals. By optimizing mitochondrial function, increasing cerebral blood flow, and promoting neural plasticity, PBM may improve aspects of cognitive function such as attention, memory, and executive function even in the absence of neurological pathology. This area of research is particularly relevant for individuals seeking to optimize their cognitive performance or maintain brain health as they age (Lee et al., 2023).
The Creative Spark: An Unexpected Finding
Perhaps the most surprising research is on creativity. A 2023 peer-reviewed study tested the effect of a single 20-minute PBM session using a Vielight Neuro Gamma device, which is engineered to target the Default Mode Network. Using gold-standard creativity assessments, researchers found that participants showed significant improvements in divergent thinking—the ability to generate novel ideas. Specifically, they saw measurable boosts in:
Fluency: The number of ideas generated.
Flexibility: The number of different categories of ideas.
Originality: The uniqueness of their ideas.
This suggests that by optimizing the function of the brain's Default Mode Network, PBM isn't just restorative; it can be generative, helping the brain operate with greater neural agility (Blanco-Campal et al., 2023).
Methodological Considerations and Future Directions
As the field of photobiomodulation for brain health continues to expand, it is crucial to address methodological considerations and outline future directions for research. The effectiveness of PBM is highly dependent on various parameters, and a deeper understanding of these factors will be essential for optimizing therapeutic outcomes and facilitating widespread clinical adoption.
Importance of Parameters
The efficacy of PBM is significantly influenced by several key parameters, including:
Wavelength: Different wavelengths of light penetrate tissues to varying depths and are absorbed by different chromophores. Red light (around 600-700 nm) and near-infrared (NIR) light (around 700-1100 nm) are most commonly used for brain applications due to their ability to penetrate the skull and reach brain tissue. NIR light, particularly around 810 nm, is often favored for its deeper penetration and optimal absorption by cytochrome c oxidase (Fernandes et al., 2024).
Power Density (Irradiance): This refers to the power of the light delivered per unit area (mW/cm²). Achieving sufficient power density is critical for the light to reach the target brain regions and elicit a therapeutic effect. Too low an irradiance may be ineffective, while excessively high levels could potentially lead to unwanted heating, though this is generally not a concern with typical PBM devices (Hennessy & Hamblin, 2016).
Fluence (Energy Density): This is the total energy delivered per unit area (J/cm²), which is a function of power density and treatment duration. Optimal fluence varies depending on the target condition and brain region. Determining the ideal fluence for specific neurological disorders is an ongoing area of research.
Pulsing vs. Continuous Wave: Light can be delivered in a continuous wave (CW) or pulsed mode. Pulsed delivery, particularly at specific frequencies (e.g., gamma frequencies), has shown promise in modulating brain oscillations and may offer distinct advantages for certain applications, such as cognitive enhancement or targeting specific brain networks (Zomorrodi et al., 2021).
Treatment Duration and Frequency: The length of each treatment session and how often treatments are administered are critical for achieving sustained therapeutic effects. Protocols vary widely across studies, and establishing standardized, evidence-based treatment regimens is a priority for future research.
Delivery Methods
Transcranial PBM (tPBM), where light is applied to the scalp, is the most common method for brain applications. However, other delivery methods are also being explored:
Intranasal PBM: This method involves delivering light through the nasal cavity, which offers a direct pathway to certain brain regions, particularly those involved in olfaction and memory. Intranasal delivery may be particularly effective for targeting deeper brain structures or for conditions where direct transcranial penetration is challenging (Rodríguez-Fernández et al., 2024).
The tissue around the nasal cavity has abundant blood capillaries with relatively slow blood flow. Intranasal photobiomodulation improves oxygenation and leads to increased adenosine triphosphate (ATP) levels in various tissues. Intracranial PBM: While more invasive, direct application of light to brain tissue during surgery or via implanted devices is being investigated for severe neurological conditions where precise targeting and higher light doses are required. This approach is primarily in experimental stages but holds potential for highly localized treatment (Lin et al., 2024).
Need for Larger, Well-Designed Clinical Trials
Despite the growing body of promising research, the field of PBM for brain health still requires more large-scale, rigorously designed clinical trials. Many existing studies are pilot trials or have small sample sizes, which can limit the generalizability of their findings. Future research should focus on:
Randomized Controlled Trials (RCTs): More RCTs with larger cohorts are needed to definitively establish the efficacy and safety of PBM for specific neurological and psychiatric conditions.
Standardized Protocols: Developing and adhering to standardized treatment protocols (wavelength, power, duration, frequency, delivery method) will be crucial for comparing results across studies and translating research findings into clinical practice.
Long-term Follow-up: Studies with longer follow-up periods are necessary to assess the durability of PBM's effects and its potential for long-term brain health maintenance.
Biomarker Identification: Identifying reliable biomarkers (e.g., changes in brain imaging, blood markers, cognitive scores) that can predict treatment response and monitor disease progression will enhance the precision and personalization of PBM therapies.
Addressing Limitations and Future Research
While PBM holds immense promise, it is important to acknowledge current limitations and areas for future research. These include optimizing device design for better brain penetration, understanding individual variability in response to PBM, and exploring combination therapies (e.g., PBM with cognitive training or pharmacotherapy) to maximize therapeutic benefits. Further research into the precise molecular and cellular pathways activated by PBM will also contribute to a more targeted and effective application of this technology.
Summary and Final Thought
Scientific evidence for photobiomodulation's benefits for the brain is growing, supported by compelling research and a clearer understanding of its mechanisms. It is not a cure for neurodegenerative diseases, but it is emerging as one of the most promising, non-pharmaceutical tools for supporting long-term brain health and optimizing cognitive function, with technology now advancing through the final stages of clinical validation.
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Conceptualization, Methodology and Research: David Priede, PhD Review & Editing: Larrie Hamilton, MHC Visualization: Michelle Ryan, MHA Project Administration and Funding Acquisition: BioLife Health Research Center |
