TRAP-AD (Transcranial Photobiomodulation for Alzheimer's Disease) is a Phase 2 randomized, triple-masked, sham-controlled clinical trial evaluating the efficacy and safety of transcranial near-infrared photobiomodulation (tPBM) in patients with amnestic mild cognitive impairment (MCI) and early Alzheimer's disease (AD). The trial uses an 808 nm near-infrared laser device delivering 300 mW/cm² to the bilateral temporal and prefrontal regions over 24 treatments (3 sessions/week for 8 weeks), with cognitive outcomes assessed at 8 weeks and 3-month follow-up[1][2].
TRAP-AD represents one of the most rigorous clinical evaluations of photobiomodulation (PBM) for Alzheimer's disease to date. Unlike earlier pilot studies with small cohorts and open-label designs, TRAP-AD is a properly powered Phase 2 RCT with 196 participants, triple-masking (participant, care provider, investigator), and a validated primary cognitive endpoint[2:1].
The trial is led by investigators at NYU Langone Health, with additional sites at Massachusetts General Hospital and the Nathan Kline Institute for Psychiatric Research. Funding comes from the NIH, the Alzheimer's Association, and device manufacturer LiteCure LLC.
The scientific rationale rests on photobiomodulation's ability to enhance cytochrome c oxidase activity in neuronal mitochondria, increase ATP production, reduce oxidative stress, and modulate neuroinflammation — all pathways that are impaired in Alzheimer's disease[3][4].
| Parameter | Value |
|---|---|
| NCT Number | NCT04784416 |
| Title | Transcranial Photobiomodulation for Alzheimer's Disease (TRAP-AD) |
| Status | Active, not recruiting |
| Phase | Phase 2 |
| Sponsor | NYU Langone Health |
| Collaborators | NIH, Alzheimer's Association, LiteCure LLC |
| Principal Investigators | Dan Iosifescu, MD (NYU Langone); Ricardo Osorio, MD (NYU Langone); Paolo Cassano, MD PhD (MGH) |
| Enrollment | 196 participants |
| Start Date | April 27, 2021 |
| Primary Completion | October 30, 2025 |
| Estimated Completion | January 31, 2026 |
| Locations | New York, NY; Boston, MA; Orangeburg, NY |
| Study Type | Interventional |
| Design | Randomized, triple-masked, parallel-group |
TRAP-AD uses a rigorous three-arm parallel design:
| Arm | Intervention | Sessions |
|---|---|---|
| Active tPBM 2.0 | 808 nm NIR laser, 300 mW/cm², ~11 min/session, bilateral temporal + prefrontal | 24 treatments over 8 weeks |
| Sham tPBM 2.0 | Identical device, no active light output | 24 treatments over 8 weeks |
| Active tPBM 1.0 | (Lower-power protocol, dose-finding) | 24 treatments over 8 weeks |
Triple-masking ensures that:
This design minimizes placebo effects, which are particularly important in studies of non-pharmacological interventions where patient expectations can strongly influence cognitive outcomes.
The trial investigates two dose levels of tPBM:
The 808 nm wavelength was chosen because near-infrared light in the 800-900 nm range penetrates skull and brain tissue most effectively, with peak absorption by cytochrome c oxidase in the mitochondrial respiratory chain[3:1].
The tPBM device delivers coherent near-infrared light (808 nm) transcranially:
| Parameter | Value |
|---|---|
| Wavelength | 808 nm (near-infrared) |
| Power density | 300 mW/cm² |
| Treatment duration | ~11 minutes per session |
| Frequency | 3 sessions/week |
| Total sessions | 24 (over 8 weeks) |
| Total energy | ~15,840 J per site over course of treatment |
| Application sites | Bilateral temporal regions + prefrontal region |
| Device manufacturer | LiteCure LLC |
Week 1-8: 24 treatments (3x per week)
├── Session 1: Bilateral temporal + prefrontal
├── Session 2: Bilateral temporal + prefrontal
└── Session 3: Bilateral temporal + prefrontal
Post-treatment: 3-month follow-up assessment
Each session applies light to multiple brain regions sequentially, targeting areas most affected by AD pathology:
Transcranial photobiomodulation operates through multiple biological pathways[4:1][5]:
Primary photoacceptor: Cytochrome c oxidase (Complex IV), the terminal enzyme in the mitochondrial electron transport chain. NIR light at 808 nm is absorbed by the CuA center of COX, enhancing oxygen consumption and ATP synthesis[3:2].
Secondary mechanisms:
The trial includes the 18F-MK-6240 PET tracer for tau imaging, allowing researchers to:
| Measure | Scale | Timepoints |
|---|---|---|
| RBANS Total Scale Index Score | Mean 100, SD 15 | Baseline, Week 8 (primary), Month 3 (follow-up) |
Repeatable Battery for the Assessment of Neuropsychological Status (RBANS): A brief, standardized cognitive battery assessing immediate memory, visuospatial/constructional ability, language, attention, and delayed memory — well-validated in MCI and early AD populations[2:3].
| Measure | Category | Timepoints |
|---|---|---|
| ACE-III (Addenbrooke's Cognitive Examination III) | Global cognition | Baseline, Week 8, Month 3 |
| Letter Comparison Test | Processing speed | Baseline, Week 8, Month 3 |
| Pattern Comparison Test | Processing speed | Baseline, Week 8, Month 3 |
| Stroop Color and Word Test | Executive function / inhibition | Baseline, Week 8, Month 3 |
| Trail Making Test (A and B) | Executive function, set-shifting | Baseline, Week 8, Month 3 |
| FNAME-12 (Face-Name Associative Memory Exam) | Associative memory | Baseline, Week 8, Month 3 |
| Letter Number sequencing | Working memory | Baseline, Week 8, Month 3 |
| SAFTEE-SI (Side Effects Checklist) | Safety/tolerability | Weekly during treatment |
The trial prioritizes cognitive outcomes across multiple domains:
Global Cognition (RBANS, ACE-III)
└── Processing Speed (Letter Comparison, Pattern Comparison)
└── Executive Function (Stroop, Trail Making)
└── Memory (FNAME-12, RBANS delayed memory)
└── Working Memory (Letter Number Sequencing)
This multi-domain assessment enables detection of both global and domain-specific treatment effects, which is important for a non-pharmacological intervention that may not produce uniform effects across all cognitive domains.
CDR 0.5-1.0: This range captures both MCI (CDR 0.5) and mild AD (CDR 1.0), ensuring the intervention is tested in the population most likely to benefit — those with established pathology but sufficient neural reserve for treatment effects.
Exclusion of other dementias: Ensures the study population has probable AD pathology, reducing heterogeneity that could obscure treatment effects. Confirmed via 18F-MK-6240 PET tau imaging.
Light-sensitive conditions: Although tPBM at 808 nm is considered safe, photosensitivity disorders are an absolute contraindication to any phototherapy.
The multi-site structure enables:
Transcranial photobiomodulation at 808 nm and 300 mW/cm² has an excellent safety profile established through decades of use in dermatology, wound healing, and neurological applications[5:1]:
| Side Effect | Frequency | Notes |
|---|---|---|
| Mild warmth at site | Common, transient | Resolves within minutes post-session |
| Headache | Rare | Usually mild, self-resolving |
| Eye irritation | Rare | Protective eyewear used during all sessions |
| Skin erythema | Very rare | Self-resolving, no scarring |
Unlike bright visible light therapy (used for seasonal affective disorder), tPBM uses:
Animal models support tPBM's mechanism in AD[6:1][7]:
Several small open-label or single-blind studies preceded TRAP-AD[8][7:1]:
| Study | N | Design | Result |
|---|---|---|---|
| Berman et al. (2019) | 13 MCI | Open-label, NIR helmet | Improved RBANS, ADAS-Cog |
| Saltmarche et al. (2017) | 8 moderate AD | Open-label, intranasal + transcranial | Improved ADAS-Cog, Neuropsychiatric Inventory |
| Bickerton et al. (2021) | 30 AD | RCT, LED helmet | Improved ACE-R, CANTAB memory |
| Blomer et al. (2020) | 11 mild AD | Open-label, transcranial | Improved cognitive composite, reduced neuroinflammation |
Limitation: All prior studies were small (N < 50), mostly unblinded, and used heterogeneous devices/protocols — insufficient for regulatory or clinical adoption.
TRAP-AD is designed to overcome these limitations:
TRAP-AD intersects with multiple Alzheimer's disease mechanisms:
| Intervention | Mechanism | Stage | Primary Route |
|---|---|---|---|
| TRAP-AD tPBM | Mitochondrial enhancement | Phase 2 | Non-invasive transcranial |
| Lecanemab | Anti-amyloid antibody | Approved | IV infusion |
| Donanemab | Anti-amyloid antibody | Approved | IV infusion |
| Blarcamesine | Muscarinic agonist | Phase 3 | Oral |
| Buntanetap | α-synuclein translation inhibitor | Phase 3 | Oral |
| SPG302 | Microtubule stabilization | Phase 1 | Oral |
tPBM is unique among AD interventions in its non-pharmacological, non-invasive approach targeting cellular energy metabolism rather than a specific pathological protein.
TRAP-AD, if positive, would represent a paradigm shift in AD treatment:
A successful tPBM intervention would:
Transcranial Photobiomodulation for Alzheimer's Disease (TRAP-AD) - NCT04784416. ↩︎
Iosifescu D, et al. Transcranial photobiomodulation for Alzheimer's disease: study protocol for a randomized, double-blind, sham-controlled trial. BMJ Open. 2022. ↩︎ ↩︎ ↩︎ ↩︎
Hamblin MR. Photobiomodulation for Alzheimer's disease. Journal of Alzheimer's Disease. 2016. ↩︎ ↩︎ ↩︎
Calvo S, et al. Mechanisms of action of photobiomodulation in the brain: the role of mitochondrial dynamics. Frontiers in Neurology. 2022. ↩︎ ↩︎
Salehpour F, et al. Transcranial photobiomodulation for brain disorders: clinical and experimental aspects. Photomedicine and Laser Surgery. 2018. ↩︎ ↩︎
Tian S, et al. Photobiomodulation reduces amyloid-beta accumulation and improves mitochondrial function in Alzheimer's disease mouse model. Journal of Alzheimer's Disease. 2021. ↩︎ ↩︎
Boutou AK, et al. Near-infrared light in neurodegenerative diseases: a systematic review. Photobiomodulation, Photomedicine, and Laser Surgery. 2022. ↩︎ ↩︎
Berman MH, et al. Photobiomodulation with near infrared light helmet in a pilot clinical study in mild cognitive impairment. Journal of Neurology and Neuroscience. 2019. ↩︎