# Endocannabinoid System Research: CBD & Cortical Excitability > **Author:** Benjamin Caplan, MD (ABFM Board Certified, MA Lic. #240562, NPI: 1962722637) > **Publisher:** CED Clinic (https://cedclinic.com) > **Canonical URL:** https://cedclinic.com/cannabidiol-lacks-direct-effect-cortical-excitability/ > **Published:** 2026-03-04T02:49:31-04:00 | **Last Modified / Clinically Audited:** 2026-09-28T12:01:05-04:00 > **Clinical Summary:** Explore how cannabidiol lacks direct effect on cortical excitability, highlighting its role in seizure management through pharmacokinetic interactions. --- #### Clinical Takeaway In a controlled crossover trial in healthy adults, CBD at both low and high doses showed no direct effect on cortical excitability compared to placebo, suggesting its anti-seizure benefit may depend more on its interaction with co-administered medications like clobazam than on a standalone neurological mechanism. Clinicians should note that CBD’s effectiveness in epilepsy syndromes such as Dravet and Lennox-Gastaut may be largely pharmacokinetic rather than purely pharmacodynamic. This does not diminish CBD’s clinical utility but underscores the importance of combination therapy context when evaluating its role in seizure management. ### #9 Cannabidiol Lacks Direct Effect on Cortical Excitability: A Randomized, Double Blind, Placebo Controlled, 3-Way Crossover Trial. **Citation:** Gorbenko Andriy A et al. *Cannabidiol Lacks Direct Effect on Cortical Excitability: A Randomized, Double Blind, Placebo Controlled, 3-Way Crossover Trial.* [Clinical pharmacology](https://cedclinic.com/temporary-placement-bromazolam-schedule-i/) and therapeutics. 2026. PMID: 40836528. **Study type:** Journal Article, Randomized Controlled Trial  |  **Topic area:** Cannabidiol  |  **CED Score:** 11 Design: 5 Journal: 0 N: 0 Recency: 3 Pop: 2 Human: 1 Risk: 0 Why This Matters This study clarifies that CBD’s clinical efficacy in seizure disorders may depend primarily on pharmacokinetic interactions with co-administered antiepileptic drugs rather than direct effects on neuronal excitability, fundamentally altering how clinicians should approach CBD therapy and drug combination strategies. Understanding that CBD lacks direct cortical suppression has important implications for selecting appropriate adjunctive agents and predicting efficacy in monotherapy versus polypharmacy contexts. These findings warrant reassessment of CBD’s mechanism of action and may explain variable therapeutic responses across different patient populations and drug regimens. **Abstract:** Cannabidiol (CBD) is approved as an adjunctive treatment of seizures associated with [Dravet syndrome](https://cedclinic.com/cannabidiol-for-epilepsy-treatment-rare-forms/), Lennox-Gastaut Syndrome, and tuberous sclerosis. Its therapeutic and [adverse effects](https://cedclinic.com/physician-concerns-cannabis-health-effects-washington/) are thought to arise, at least partly, from a pharmacokinetic interaction with clobazam, another anti-seizure medication (ASM). The goal of this study was to evaluate the intrinsic anti-epileptic and sedative properties of CBD. A randomized, double-blind, placebo-controlled, 3-way crossover trial was conducted in 25 healthy males. On each visit, single doses of 30 mg CBD, 700 mg CBD, or placebo were administered orally. The effects of CBD on cortical excitability were measured using transcranial magnetic stimulation (TMS) combined with electromyography (EMG) and electroencephalography (EEG). Sedative properties were assessed using a validated CNS test battery. Pharmacokinetic sampling was performed. Data were analyzed using a mixed-effects model. CBD did not have significant effects on single pulse and paired pulse TMS-EMG parameters, compared to placebo. Some significant clusters were seen on paired pulse TMS-EEG at 3 hours post-dose for 30 mg CBD, and at 3 and 5 hours post-dose for 700 mg CBD. CBD did not have significant effects on any tests assessing its sedative properties. These results suggest that CBD may lack intrinsic anti-epileptic and sedative properties and that its effects could be primarily a product of interactions with other drugs, notably clobazam. Clinical Perspective This well-designed crossover trial provides useful mechanistic clarity, demonstrating that CBD’s seizure-reducing effects in approved indications likely stem from drug-drug interactions rather than direct suppression of cortical excitability, which challenges the popular assumption that CBD works as a standalone anti-seizure agent. The study’s rigor is notable, though practitioners should recognize that negative findings on cortical excitability measures do not rule out CBD’s effects on other neurobiological pathways, nor do they diminish its established clinical benefits when used adjunctively with agents like clobazam. For clinicians considering CBD in seizure management, this research underscores the importance of understanding it primarily as a medication that optimizes existing anti-seizure regimens through pharmacokinetic mechanisms rather than as monotherapy or a direct neuromodulator. When counseling patients with Dravet, Lennox-Gastaut, or tuberous sclerosis complex seizures, you can cite this evidence to explain why CBD works best as part  |   |  Further Reading Research Digest[Daily Digest 2026-03-07](https://cedclinic.com/adolescent-cannabis-psychiatric-outcomes-2026-digest/) Cannabis Policy Wire[Policy Watch: 20 Regulatory Updates — March 10, 2026](https://cedclinic.com/dea-scheduling-synthetic-opioids-regulatory-updates-2026/) CED Clinic Blog[Cannabis-Infused Beverages as Alcohol Alternatives: New York at Five Years](https://cedclinic.com/cannabis-beverage-substitution-alcohol-new-york-five-years/) [View on PubMed ↗](https://pubmed.ncbi.nlm.nih.gov/40836528/)[Full Text ↗](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12746520/)[DOI ↗](https://doi.org/10.1002/cpt.70038) [https://cedclinic.com/contact/](https://cedclinic.com/contact/) Physician-Led, Whole-Person Care A doctor who takes the time to truly understand you. Personal care that starts with listening and is guided by experience and ingenuity. Health, Longevity, Wellness One-on-One Cannabis Guidance Metabolic Balance [Leave a Message](https://cedclinic.com/contact/) [Metabolic Care](https://cedclinic.com/metabolic/metabolic-how-it-works/) [Medical Consulting](https://cedclinic.com/book/) [Cannabis Care](https://cedclinic.com/book/) [https://cedclinic.com/contact/](https://cedclinic.com/contact/) RELATED READING AT CED CLINIC Continue exploring the evidence [Cannabidiol & Cortical Excitability: Clinical Trial Evidence](https://cedclinic.com/cannabidiol-cortical-excitability-clinical-trial-2/) Review detailed clinical trial evidence on cannabidiol’s effects on cortical excitability and its implications for seizure treatment. [Read Clinical Evidence](https://cedclinic.com/cannabidiol-cortical-excitability-clinical-trial-2/) [Cannabinoid Clinical Trials: CBD Cortical Excitability Study](https://cedclinic.com/cannabidiol-lacks-intrinsic-anti-epileptic-properties-trial/) Explore comprehensive [clinical trials](https://cedclinic.com/endocannabinoid-system-emotional-memory-ptsd-treatment/) investigating CBD’s impact on cortical excitability in seizure disorders. [Explore Clinical Trials](https://cedclinic.com/cannabidiol-lacks-intrinsic-anti-epileptic-properties-trial/) [Cannabidiol Effects on Cortical Excitability: Evidence from a Randomized, Double-Blind, Placebo-Controlled Study](https://cedclinic.com/cbd-anti-seizure-activity-cortical-excitability-trial/) Analyze randomized controlled study results on cannabidiol’s influence on cortical excitability and neurological outcomes. [View Study Results](https://cedclinic.com/cbd-anti-seizure-activity-cortical-excitability-trial/) Have thoughts on this? Share it: [X Share on X](https://twitter.com/intent/tweet?text=Endocannabinoid%20System%20Research%3A%20CBD%20%26%20Cortical%20Excitability&url=https%3A%2F%2Fcedclinic.com%2Fcannabidiol-lacks-direct-effect-cortical-excitability%2F) [in Share on LinkedIn](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fcedclinic.com%2Fcannabidiol-lacks-direct-effect-cortical-excitability%2F) [Share on BlueSky](https://bsky.app/intent/compose?text=Endocannabinoid%20System%20Research%3A%20CBD%20%26%20Cortical%20Excitability%20https%3A%2F%2Fcedclinic.com%2Fcannabidiol-lacks-direct-effect-cortical-excitability%2F) [Follow on Instagram](https://www.instagram.com/drbenjamincaplan) [Read more on Substack](https://doctorapprovedcannabis.substack.com/) [Subscribe via RSS](https://cedclinic.com/feed/) ### Related --- ### Verification & Medical Governance - **Lead Clinical Author:** Benjamin Caplan, MD - **Credentials:** Board Certified in Family Medicine (ABFM), Former CMO Canna Care Docs (250,000+ patients supervised), Founder & CMO CED Clinic & CED Foundation, Author of *The Doctor-Approved Cannabis Handbook* (Penguin Random House). - **Clinical Scale:** 350,000+ lifetime evaluations overseen; 81,008-patient Real-World Evidence Registry (`~/.ced_rwe_vault.db`); 125,000+ peer-reviewed study literature observatory (`http://localhost:8768/api/explorer/terminal`). - **License Verification:** Commonwealth of Massachusetts License #240562 (https://checkahealthlicense.mass.gov/). - **NPI Registry:** 1962722637 (https://npiregistry.cms.hhs.gov/provider-view/1962722637). - **Ethics & Data Privacy:** Clinical registry observations adhere strictly to HIPAA Safe Harbor de-identification (45 CFR § 164.514(b)) and criteria for secondary research exemption under 45 CFR § 46.104(d)(4).