In a 4-year study of 200 neuropathic pain patients, cannabis therapy achieved a 91.5% clinical response rate—and a novel light-emission biomarker (UPE) tracked anxiety changes 6x better than pain changes.
Pain medicine specialists, neuropathic pain patients, biomarker researchers, and medical cannabis program administrators.
What the researchers found
This study has two distinct contributions. The first is clinical: 200 adults with confirmed neuropathic pain received cannabis therapy and were followed for 48 months—one of the longest follow-up periods in cannabis pain research. The clinical response rate was 91.5%, suggesting that for neuropathic pain specifically, cannabis therapy is highly effective in the real world.
The second contribution is methodological: the researchers tested ultra-weak photon emission (UPE), measured via gas discharge visualization (GDV/Biowell), as a potential biomarker. UPE measures extremely faint light that biological tissues emit—a measurement at the frontier of biophysics.
The biomarker finding was surprising. UPE measurements correlated strongly with anxiety (GAD-7: r = 0.579) but weakly with pain (NRS: r = 0.092)—a 6.2-fold difference. In practical terms, the Biowell UPE measurement could discriminate clinically meaningful anxiety changes (AUC = 0.744) but not pain changes (AUC = 0.550, essentially random). Mixed-effects modeling confirmed that UPE predicted anxiety scores but not pain scores.
This specificity for anxiety over pain is interesting because it suggests these are biologically distinct processes that respond to cannabis differently—or at least produce different measurable biological signals.
Why it matters
The 91.5% response rate for neuropathic pain over 4 years is one of the strongest real-world outcomes in the cannabis pain literature—particularly given RTHC-00170's finding that neuropathic pain patients use cannabis more intensively than other pain patients and RTHC-00200's identification of CBG as a potential nerve pain treatment. The biomarker work is more exploratory but points toward objective measurement tools for conditions that currently rely entirely on self-report.
The numbers in context
N = 200. 48-month follow-up. 91.5% clinical response rate. UPE-anxiety correlation: r = 0.579 (strong). UPE-pain correlation: r = 0.092 (weak). 6.2-fold difference in correlation strength. Anxiety AUC = 0.744. Pain AUC = 0.550.
How the study worked
Prospective cohort study. 200 adults with electrodiagnostically confirmed neuropathic pain receiving cannabis therapy for 48 months. Assessments: NRS (pain), GAD-7 (anxiety), Biowell UPE measurements. Correlation analyses, ROC analysis, and mixed-effects modeling for UPE specificity.
Who was studied
N=200 adults aged 18-65 with confirmed neuropathic pain, receiving cannabis therapy in a clinical setting.
What this study cannot tell us
No control group or placebo arm—the 91.5% response rate could partly reflect placebo effects, regression to the mean, or other treatments. UPE/Biowell is a novel and controversial measurement technology with limited validation. All patients had neuropathic pain—results don't apply to other pain types. Self-selected patients receiving cannabis therapy may be predisposed to report improvement. Israeli medical cannabis program context may differ from other healthcare systems.
How to read the evidence
Prospective cohort with long follow-up and confirmed diagnoses—strong for real-world effectiveness but limited by lack of randomization or control group.
When this study was published
Published in 2025 with 4 years of follow-up data from an Israeli medical cannabis program.
The bigger picture
The 91.5% neuropathic pain response rate contrasts sharply with RTHC-00182's null result for CBD in knee osteoarthritis and RTHC-00158's mixed results in cancer symptoms. This reinforces the emerging pattern: cannabis appears most effective for neuropathic pain specifically, less effective for other pain types. The anxiety-specific biomarker finding connects to RTHC-00196's evidence that higher CBD doses improved anxiety in cancer patients—cannabis's anxiety-reducing effects may be a distinct therapeutic pathway from its analgesic effects.
Replication
Not stated in abstract.
Funding
Not reported in abstract.
Conflicts of interest
Not reported in abstract.
Questions still open
- Would a randomized controlled trial of cannabis for neuropathic pain confirm the high response rate? Can UPE technology be validated independently for anxiety monitoring? Does the anxiety-pain dissociation in biomarker response reflect different biological mechanisms or just different measurement sensitivities?
Read the original research
Ultra-Weak Photon Emission Demonstrates Specificity for Anxiety over Pain in Cannabis-Treated Chronic Neuropathic Pain: A Biomarker Validation Study.
Bioengineering (Basel, Switzerland), 12(12)
Bioengineering is a peer-reviewed journal known for publishing innovative research in the field of bioengineering.
Citation
Yassin, Mustafa; Robinson, Dror; Khatib, Muhammad; Murad, Hamza; Qawasme, Feras; Lavon, Eitan. (2025). Ultra-Weak Photon Emission Demonstrates Specificity for Anxiety over Pain in Cannabis-Treated Chronic Neuropathic Pain: A Biomarker Validation Study.. Bioengineering (Basel, Switzerland), 12(12). https://doi.org/10.3390/bioengineering12121359
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