Post-traumatic stress disorder (PTSD) is a mental health condition triggered by experiencing or witnessing a traumatic event, such as war, natural disasters, or violence. Symptoms include intrusive memories, anxiety, depression, and cognitive impairments like memory loss or difficulty concentrating . Current treatments, such as psychotherapy and medications, are not effective for everyone, highlighting the need for innovative approaches. Recent research has explored photobiomodulation (PBM), a non-invasive therapy using red or near-infrared light, as a potential solution. Below, we synthesize findings from four key studies to explain how PBM works, its effects in animal models, and early human trials.
Understanding PTSD: Memory Dysregulation and Comorbidities
PTSD is characterized by contextual amnesia, where individuals struggle to distinguish safe environments from traumatic ones. For example, someone with PTSD might feel intense fear in a harmless setting that reminds them of the trauma . This memory impairment is linked to dysfunction in brain regions like the hippocampus and prefrontal cortex, which are critical for learning, memory, and emotional regulation.
Additionally, PTSD often co-occurs with other conditions, such as anxiety, depression, and chronic pain—a phenomenon called PTSD-like comorbidities. These symptoms further disrupt daily life and complicate treatment .
How Photobiomodulation (PBM) Works
PBM uses low-level red (630–700 nm) or near-infrared (800–1000 nm) light to stimulate cellular activity. The light is absorbed by cytochrome c oxidase in mitochondria, the energy-producing centers of cells. This process increases ATP production (the cell’s energy currency) and reduces oxidative stress, promoting cell survival and repair . PBM also triggers anti-inflammatory responses and enhances the release of growth factors like BDNF (brain-derived neurotrophic factor), which supports nerve cell growth and synaptic plasticity .
When applied transcranially (via a helmet or LED device), the light penetrates the skull to reach deep brain regions, making it a promising tool for treating brain disorders like PTSD .
Animal Studies: PBM Prevents PTSD-like Symptoms
1. Reversing Contextual Amnesia
In a 2021 study by Li et al. , rats exposed to traumatic stress (foot shocks and restraint) developed contextual amnesia, failing to recognize safe environments. However, rats treated with PBM immediately after trauma showed preserved contextual fear memory. Specifically, PBM:
• Increased ATP levels in the hippocampus (a key memory center).
• Did not affect stress hormones like corticosterone, indicating its effects are independent of stress reduction.
• Improved freezing behavior (a measure of fear response) during memory tests, showing better discrimination between safe and dangerous contexts.
Notably, PBM was effective in both male and female rats, suggesting gender-neutral benefits .
2. Preventing Comorbidities in Complex PTSD
Li et al. also tested PBM in rats subjected to repeated underwater trauma, a model of complex PTSD with multiple stressors. Rats receiving early PBM interventions:
• Showed reduced anxiety-like behaviors (e.g., decreased exploration in the elevated plus maze).
• Improved cognitive performance in novel object recognition tests.
• Avoided developing comorbidities like depression and chronic pain.
The researchers attributed these effects to PBM’s ability to protect neurons in the prefrontal cortex and hippocampus, reducing inflammation and promoting synaptic repair.
Human Trials: PBM Improves Cognition and PTSD Symptoms
1. Gulf War Illness (GWI) and PTSD
Martin et al. conducted a randomized controlled trial on veterans with GWI, a condition linked to PTSD and cognitive impairments. Participants received transcranial PBM (810 nm LED) or sham treatment for 7.5 weeks. Key findings included:
• Cognitive improvements: Enhanced attention, memory, and processing speed in the PBM group.
• Symptom reduction: Significant decreases in PTSD symptoms (measured by the Clinician-Administered PTSD Scale) that persisted for at least one month post-treatment.
• Long-term benefits: Unlike the sham group, which showed temporary improvements, PBM recipients maintained their gains over time.
These results suggest PBM could be a viable adjunct to traditional therapies for veterans.
2. Chronic Traumatic Brain Injury (TBI)
Naeser et al. studied PBM in patients with chronic TBI, many of whom had PTSD-like symptoms. Participants received 810 nm LED therapy over 12 weeks. The study found:
• Cognitive recovery: Improved verbal memory, attention, and executive function.
• Functional gains: Participants reported better daily living skills and reduced fatigue.
• Safety: No serious side effects were reported, confirming PBM’s tolerability.
The researchers hypothesized that PBM’s ability to increase blood flow and BDNF levels in the brain contributed to these improvements.
Why PBM Stands Out: Mechanisms and Advantages
1. Targeting Root Causes
Unlike medications that mask symptoms, PBM addresses cellular dysfunction in the brain. By boosting energy production and reducing inflammation, it supports long-term neural repair .
2. Non-Invasive and Safe
PBM does not involve drugs, surgery, or radiation. Studies report minimal side effects, typically limited to mild redness or warmth at the treatment site .
3. Versatility
PBM can be combined with other therapies (e.g., psychotherapy) and tailored to individual needs. For example, different light wavelengths may target specific brain regions or symptoms .
Challenges and Future Directions
While promising, PBM research is still in its early stages. Key challenges include:
• Optimal Parameters: Determining the best light wavelength, intensity, and treatment duration for PTSD. Current studies use varying protocols, making direct comparisons difficult .
• Larger-Scale Trials: Most human studies involve small sample sizes. Larger trials are needed to confirm efficacy and safety in diverse populations.
• Long-Term Follow-Up: More data is required to assess the durability of PBM’s effects beyond a few months.
Future research should also explore PBM’s potential in preventing PTSD after trauma (e.g., in first responders) and its role in treating comorbidities like chronic pain .
Conclusion
Photobiomodulation offers a novel, non-invasive approach to treating PTSD by addressing both memory impairments and comorbid symptoms. Animal studies demonstrate its ability to reverse contextual amnesia and protect against long-term brain damage, while early human trials show cognitive and emotional improvements. With its safety profile and potential to enhance neural health, PBM could become a game-changing therapy for PTSD. As research progresses, it is critical to refine treatment protocols and conduct larger-scale trials to unlock its full potential.
References：
1. Li Y, Dong Y, Yang L, et al. Photobiomodulation prevents PTSD-like memory impairments in rats. Mol Psychiatry. 2021;26(11):6666-6679. doi:10.1038/s41380-021-01088-z
2. Li Y, Dong Y, Yang L, et al. Transcranial photobiomodulation prevents PTSD-like comorbidities in rats experiencing underwater trauma. Transl Psychiatry. 2021;11(1):270. doi:10.1038/s41398-021-01389-5
3. Martin PI, Chao L, Krengel MH, et al. Transcranial Photobiomodulation to Improve Cognition in Gulf War Illness. Front Neurol. 2021;11:574386. doi:10.3389/fneur.2020.574386
4. Naeser MA, Martin PI, Ho MD, et al. Transcranial, Red/Near-Infrared Light-Emitting Diode Therapy to Improve Cognition in Chronic Traumatic Brain Injury. Photomed Laser Surg. 2016;34(12):610-626. doi:10.1089/pho.2015.4037
