# CBD and Nonseizure Outcomes in Epilepsy: What a New Systematic Review Shows > **Author:** Benjamin Caplan, MD (ABFM Board Certified, MA Lic. #240562, NPI: 1962722637) > **Publisher:** CED Clinic (https://cedclinic.com) > **Canonical URL:** https://cedclinic.com/cbd-nonseizure-outcomes-epilepsy/ > **Published:** 2026-08-05T17:16:06-04:00 | **Last Modified / Clinically Audited:** 2026-09-27T22:01:18-04:00 > **Clinical Summary:** Explore the latest systematic review on CBD nonseizure outcomes epilepsy, highlighting improvements in cognition, behavior, and quality of life beyond seizure --- CED Clinical Relevance #85 [Cannabis Science](https://cedclinic.com/biphasic-effects-of-cannabis/) Evidence Report A PRISMA-guided systematic review pooled 32 studies and 1,343 patients with developmental and epileptic encephalopathies and complex treatment-resistant epilepsies outside the three FDA-approved CBD syndromes, and found improvement reported in at least one nonseizure domain in 31 of 32 studies, while the underlying evidence base remains mostly observational. Clinical Insight | CED Clinic Highly purified CBD (Epidiolex/Epidyolex) is FDA-approved for seizures in Lennox-Gastaut syndrome, [Dravet syndrome](https://cedclinic.com/cannabidiol-for-epilepsy-treatment-rare-forms/), and tuberous sclerosis complex. This systematic review looked past seizure counts, at patients with other developmental and epileptic encephalopathies and complex treatment-resistant epilepsies, to ask whether CBD affects cognition, behavior, communication, motor function, sleep, and [quality of life](https://cedclinic.com/cannabis-policy-enforcement-february-26-2026/). Thirty-one of 32 included studies reported improvement in at least one nonseizure domain, but nearly all of that evidence comes from observational, open-label, or retrospective designs with moderate to high risk of bias. CBDEpilepsySystematic ReviewCognition & BehaviorSafety Audience Parents and caregivers of children with developmental and epileptic encephalopathies, adults with treatment-resistant epilepsy, pediatric epileptologists, neurologists, and cannabis-science readers Primary Topic CBD nonseizure outcomes in developmental and epileptic encephalopathies Source [Read the full source](https://pubmed.ncbi.nlm.nih.gov/42520581/) A PRISMA-guided systematic review published July 14, 2026 in Epilepsy Research pooled 32 studies of highly purified CBD in patients with developmental and epileptic encephalopathies and complex treatment-resistant epilepsies beyond Lennox-Gastaut, Dravet, and tuberous sclerosis complex. Thirty-one of 32 studies reported improvement in at least one nonseizure outcome, most consistently in neuropsychiatric function and cognition. What This Study Teaches Us The review separates seizure control from everything else families and clinicians track: cognition, behavior, communication, motor function, sleep, development, concomitant medication burden, healthcare utilization, and global change. It reports how many of the included studies found improvement in each of those eleven domains. Why This Matters Families managing developmental and epileptic encephalopathies often care as much about alertness, communication, and daily function as about seizure counts. Most rigorous CBD trial evidence has focused narrowly on seizures in three specific syndromes, so a review that gathers nonseizure signals across a broader population fills a real information gap, even though the underlying studies are largely observational. Study Snapshot Study Type PRISMA-guided systematic literature review; search conducted March 2024 Population 1,343 patients across 32 studies with developmental and epileptic encephalopathies (DEEs) and complex treatment-resistant epilepsies (TREs), excluding Lennox-Gastaut syndrome, [Dravet syndrome](https://cedclinic.com/cannabidiol-for-epilepsy-treatment-rare-forms/), and tuberous sclerosis complex Intervention Highly purified plant-derived CBD oral solution (Epidiolex in the US / Epidyolex in the EU) Comparator No uniform comparator; narrative synthesis of mostly observational and open-label studies Databases Searched Embase, Medline, and Cochrane Central Register of Controlled Trials Domains Assessed Neuropsychiatric function, [cognitive function](https://cedclinic.com/reverse-cholesterol-transport-function-cannabis-users/), concomitant antiseizure medication use, communication, behavior, motor function, healthcare utilization, [quality of life](https://cedclinic.com/cannabis-policy-enforcement-february-26-2026/), global change, sleep, and development Improvement Reported 31 of 32 studies reported improvement in at least 1 nonseizure outcome; neuropsychiatric function (9/9 studies) and [cognitive function](https://cedclinic.com/reverse-cholesterol-transport-function-cannabis-users/) (9/9 studies) showed the most consistent reporting Most Common Adverse Events Diarrhea (17-34%), vomiting (5-50%), and decreased appetite (7-20%), consistent with CBD’s known safety profile Journal Epilepsy Research Published July 14, 2026 Authors Debopam Samanta, Lisa Moore-Ramdin, Marco Navetta, and Antonietta Coppola PMID / DOI 42520581 / 10.1016/j.eplepsyres.2026.107873 Major Limitation Mostly observational, open-label, or retrospective studies with moderate to high risk of bias, and no uniform comparator or blinding Clinical Bottom Line Across 32 studies and 1,343 patients with developmental and epileptic encephalopathies and complex treatment-resistant epilepsies, highly purified CBD was associated with reported improvement in at least one nonseizure domain in nearly every included study. The finding is consistent and broad, but it rests on observational evidence with meaningful bias risk, so it should be read as hypothesis-supporting rather than confirmatory. What the Review Looked At The authors searched Embase, Medline, and Cochrane Central in March 2024 for studies reporting nonseizure outcomes after CBD initiation in patients with developmental and epileptic encephalopathies and complex treatment-resistant epilepsies other than Lennox-Gastaut syndrome, [Dravet syndrome](https://cedclinic.com/cannabidiol-for-epilepsy-treatment-rare-forms/), and tuberous sclerosis complex, the three syndromes CBD is currently FDA-approved to treat. Thirty-two studies covering 1,343 patients met inclusion criteria. Results were narratively summarized rather than statistically pooled, because study designs and outcome measures varied widely. Where Improvement Was Reported Every one of the 9 studies that assessed neuropsychiatric function and every one of the 9 studies that assessed [cognitive function](https://cedclinic.com/reverse-cholesterol-transport-function-cannabis-users/) reported improvement in at least some patients. Communication (7 of 7 studies) and behavior (7 of 7 studies) showed the same pattern. Motor function (6 of 6), healthcare utilization (5 of 5), [quality of life](https://cedclinic.com/cannabis-policy-enforcement-february-26-2026/) (5 of 5), global change (4 of 4), sleep (2 of 2), and development (2 of 2) also showed improvement in every study that measured them, and 7 of 8 studies reported reduced use of concomitant antiseizure medications. The Adverse Event Pattern Reported adverse events were consistent with CBD’s established safety profile and were predominantly gastrointestinal: diarrhea in 17 to 34 percent of patients, vomiting in 5 to 50 percent, and decreased appetite in 7 to 20 percent, depending on the study. Wide ranges across studies reflect differences in dosing, population, concomitant medications, and how adverse events were tracked and reported. Why Bias Risk Is High The authors themselves describe the included evidence as mainly observational studies with moderate to high risk of bias. Most were open-label, uncontrolled, or retrospective, without blinding or a placebo comparator. When every included study reports improvement in a domain, that consistency can reflect a genuine effect, but it can also reflect publication bias, expectation effects, or the tendency for open-label studies to report favorably. What This Means Beyond the Three Approved Syndromes CBD’s FDA approval is specific to seizures in Lennox-Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex. This review looked at a broader and more heterogeneous population of developmental and epileptic encephalopathies and treatment-resistant epilepsies. The nonseizure findings do not extend the approved indication and should not be read as evidence that CBD is proven effective for cognition or behavior in these other syndromes; they identify a research signal worth confirming in controlled trials. How Strong Is This Evidence? A PRISMA-guided systematic search across three major databases, a large pooled sample of 1,343 patients, a broad and clinically meaningful set of nonseizure domains, and a consistent direction of reported effect across nearly all included studies make this a useful synthesis of the existing literature on CBD’s effects beyond seizure counts. Where This Paper Deserves Skepticism The review pools mostly observational, open-label, and retrospective studies with moderate to high risk of bias. There was no uniform comparator, no blinding in most included studies, and outcomes were narratively summarized rather than statistically pooled, so effect sizes and confidence intervals are not available. A near-universal pattern of reported improvement across every domain is also consistent with publication and reporting bias in an open-label literature. What This Paper Does Not Show This review does not prove that CBD causes improvement in cognition, behavior, or any other nonseizure domain, does not establish an effect size, does not extend CBD’s FDA-approved indication beyond Lennox-Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex, does not isolate CBD’s direct effect from possible improvement driven by reduced seizure burden or reduced antiseizure medication load, and does not establish long-term safety beyond the adverse events captured in the underlying studies. How This Fits With the Broader Clinical Conversation CBD’s regulatory approval rests on randomized controlled trials that measured seizure frequency in three specific syndromes. This review shifts the lens to nonseizure outcomes and to a broader population of developmental and epileptic encephalopathies and treatment-resistant epilepsies. The next useful step is prospective, controlled research with standardized, validated cognitive and behavioral measures, a defined comparator, and prespecified nonseizure endpoints, so the consistent observational signal identified here can be tested rigorously. Dr. Caplan’s Take *Families living with developmental and epileptic encephalopathies frequently tell me that alertness, communication, and mood matter as much as seizure counts. This review takes that priority seriously and gathers a genuinely broad set of nonseizure signals, which is valuable groundwork.* *I would not present this as proof that CBD improves cognition or behavior. It is a well-organized summary of a mostly observational literature with real bias risk. It supports a careful, individualized conversation and continued monitoring, not a general claim of nonseizure benefit.* What a Careful Reader Should Take Away Nearly every included study reported improvement in at least one nonseizure domain, but because the underlying evidence is largely observational with meaningful bias risk, the finding should be treated as a research signal that needs controlled confirmation, not an established nonseizure benefit. Evidence Interpretation Guide Table of Contents - [How to Interpret the Nonseizure Outcomes Review](#How_to_Interpret_the_Nonseizure_Outcomes_Review)[A Four-Step Reading Frame](#A_Four-Step_Reading_Frame) - [The Same Study Can Mean Different Things Depending on the Question Being Asked](#The_Same_Study_Can_Mean_Different_Things_Depending_on_the_Question_Being_Asked)[A Broad Signal, Not a Guarantee](#A_Broad_Signal_Not_a_Guarantee) - [Useful Hypothesis-Generating Synthesis](#Useful_Hypothesis-Generating_Synthesis) - [Near-Universal Improvement Is a Red Flag as Much as a Signal](#Near-Universal_Improvement_Is_a_Red_Flag_as_Much_as_a_Signal) - [Narrative Synthesis Cannot Replace Meta-Analysis](#Narrative_Synthesis_Cannot_Replace_Meta-Analysis) - [Extends Beyond the Three Approved Syndromes](#Extends_Beyond_the_Three_Approved_Syndromes) - [Watch for Gastrointestinal Effects](#Watch_for_Gastrointestinal_Effects) - [Controlled Trials With Standardized Measures Are the Next Step](#Controlled_Trials_With_Standardized_Measures_Are_the_Next_Step) - [Evidence Tier Should Match Communication](#Evidence_Tier_Should_Match_Communication) - [Frequently Asked Questions](#Frequently_Asked_Questions)[Related](#Related) ## How to Interpret the Nonseizure Outcomes Review A systematic search process improves confidence that the literature was gathered comprehensively. A narrative summary of observational studies is still a lower tier of evidence than a randomized controlled trial. ### A Four-Step Reading Frame **Note the study design**This is a systematic review of mostly observational and open-label studies, not a randomized controlled trial or meta-analysis with pooled effect sizes. **Respect the consistency, cautiously**Improvement was reported in nearly every study and domain, which is notable, but consistent reporting across open-label studies can also reflect bias rather than a uniform true effect. **Separate seizure control from nonseizure effects**Some reported cognitive or behavioral improvement may follow indirectly from fewer seizures or reduced antiseizure medication burden, not necessarily a direct effect of CBD. **Watch for the adverse event pattern**Gastrointestinal effects, including diarrhea, vomiting, and decreased appetite, were common and should be part of any monitoring plan. The Research Question Does highly purified CBD improve nonseizure outcomes such as cognition, behavior, and communication in developmental and epileptic encephalopathies and complex treatment-resistant epilepsies? The Patient Question Beyond seizure counts, could CBD help my child or me think, communicate, or function better day to day? The Bottom Line The reported signal is broad and consistent, but it comes from observational evidence that needs controlled confirmation before it can guide expectations. CED Perspective Lens ## The Same Study Can Mean Different Things Depending on the Question Being Asked Scientific papers rarely answer a single question. Patients, clinicians, researchers, policymakers, and critics often read the same data differently. The perspectives below explore how this study looks through several evidence-based lenses. Lens Overview Eight perspectives keep a broad, mostly favorable observational signal from being read as proof of a nonseizure benefit. #### A Broad Signal, Not a Guarantee Most studies in this review reported some improvement in alertness, communication, behavior, or another nonseizure domain. Track specific, measurable goals with your care team rather than expecting improvement across every domain at once. Lens takeaway Ask which nonseizure domain matters most for your family and monitor it specifically. #### Useful Hypothesis-Generating Synthesis The review organizes a scattered observational literature into a clear picture of which nonseizure domains have been studied and how often improvement was reported. It should inform counseling and monitoring priorities, not stand in for controlled trial evidence when discussing expected benefit. Lens takeaway Use it to guide what to monitor, not to promise a specific outcome. #### Near-Universal Improvement Is a Red Flag as Much as a Signal When 31 of 32 studies report improvement in an open-label literature, publication bias and selective reporting are plausible contributors. The absence of pooled effect sizes or confidence intervals limits how much weight any single domain’s finding should carry. Lens takeaway Consistency across weak-design studies is not the same as consistency across strong-design studies. #### Narrative Synthesis Cannot Replace Meta-Analysis Without a common comparator or standardized outcome measures, the review cannot quantify how large any nonseizure effect might be. Study quality across the 32 included papers was not uniform, and the review’s own assessment flagged moderate to high bias risk. Lens takeaway Read the domain-level counts as descriptive, not as an effect estimate. #### Extends Beyond the Three Approved Syndromes Randomized trial evidence for CBD has focused on seizure counts in Lennox-Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex. This review gathers evidence from a wider population of developmental and epileptic encephalopathies and treatment-resistant epilepsies, and from a wider set of outcomes than seizures alone. Lens takeaway It broadens the question but does not replace syndrome-specific randomized evidence. #### Watch for Gastrointestinal Effects Diarrhea, vomiting, and decreased appetite were the most commonly reported adverse events, consistent with CBD’s known tolerability profile. Wide reported ranges suggest these effects vary meaningfully by dose, population, and concomitant medications, so individualized monitoring matters. Lens takeaway Build gastrointestinal monitoring into any CBD trial, alongside nonseizure outcome tracking. #### Controlled Trials With Standardized Measures Are the Next Step Prospective, controlled studies with validated cognitive and behavioral instruments, a defined comparator, and prespecified nonseizure endpoints would let researchers test this signal directly. Disentangling a direct CBD effect from improvement driven by fewer seizures or lower antiseizure medication burden is an important open question. Lens takeaway The field needs trials designed around nonseizure endpoints, not seizure counts alone. #### Evidence Tier Should Match Communication A systematic review of observational studies is a meaningful contribution, but it should be communicated at the evidence tier it represents. Regulatory and clinical guidance should continue to distinguish the approved seizure indication from unproven nonseizure claims. Lens takeaway Describe this as a research signal, not as expanded proof of benefit. Join the Conversation Have a question about how this applies to your situation? [Ask Dr. Caplan](https://benjamincaplan.com/ask-dr-caplan) Want to discuss this topic with other patients and caregivers? [Join the forum discussion](https://cedclinic.com/interact/discussion-forums/) [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/) Share this Evidence Watch [X](https://twitter.com/intent/tweet?text=CBD+and+Nonseizure+Outcomes+in+Epilepsy%3A+What+a+New+Systematic+Review+Shows&url=https%3A%2F%2Fcedclinic.com%2Fcbd-nonseizure-outcomes-epilepsy-systematic-review%2F) [LinkedIn](https://www.linkedin.com/sharing/share-offsite/?url=https%3A%2F%2Fcedclinic.com%2Fcbd-nonseizure-outcomes-epilepsy-systematic-review%2F) [BlueSky](https://bsky.app/intent/compose?text=CBD+and+Nonseizure+Outcomes+in+Epilepsy%3A+What+a+New+Systematic+Review+Shows%20https%3A%2F%2Fcedclinic.com%2Fcbd-nonseizure-outcomes-epilepsy-systematic-review%2F) [Instagram](https://www.instagram.com/drcaplan/) [Substack](https://doctorapprovedcannabis.substack.com/) [RSS](https://cedclinic.com/feed/) Source: [A systematic review of highly purified cannabidiol in developmental and epileptic encephalopathies and complex treatment-resistant epilepsies: Nonseizure outcomes.](https://pubmed.ncbi.nlm.nih.gov/42520581/) Related Reading at CED Clinic Continue exploring the evidence [CBD in Childhood Epilepsy: What the Evidence Actually Shows](https://cedclinic.com/cannabidiol-pediatric-epilepsy-dosing-2025-review/) Background on randomized trial evidence, dosing, and drug interactions for CBD in pediatric epilepsy, including the syndromes with FDA-approved seizure indications. [Read the pediatric epilepsy review](https://cedclinic.com/cannabidiol-pediatric-epilepsy-dosing-2025-review/) [Clinical Insights on CBD Metabolic Effects from Epidiolex Trials](https://cedclinic.com/cbd-metabolic-effects-epidiolex-clinical-trials/) A closer look at metabolic and weight-related findings from Epidiolex [clinical trials](https://cedclinic.com/endocannabinoid-system-emotional-memory-ptsd-treatment/), useful context for monitoring beyond seizure counts. [Read the metabolic effects coverage](https://cedclinic.com/cbd-metabolic-effects-epidiolex-clinical-trials/) [CBD Shows Promise, But This Review Warns the Hype Is Outpacing the Science](https://cedclinic.com/cbd-drug-interactions-epilepsy-clinical-evidence-safety/) A companion evidence-quality discussion on where CBD research in epilepsy is strong, where it is thin, and what drug interactions to watch for. [Read the evidence-quality review](https://cedclinic.com/cbd-drug-interactions-epilepsy-clinical-evidence-safety/) ## Frequently Asked Questions What did this systematic review study? It reviewed 32 studies of 1,343 patients with developmental and epileptic encephalopathies and complex treatment-resistant epilepsies, looking at nonseizure outcomes after starting highly purified CBD. Which patients were included? Patients with developmental and epileptic encephalopathies and complex treatment-resistant epilepsies other than Lennox-Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex, the three syndromes CBD is FDA-approved to treat. What nonseizure outcomes were assessed? Neuropsychiatric function, cognitive function, concomitant antiseizure medication use, communication, behavior, motor function, healthcare utilization, quality of life, global change, sleep, and development. How many studies reported improvement? 31 of 32 included studies reported improvement in at least one nonseizure outcome in at least some patients. What were the most common side effects? Gastrointestinal effects were most common: diarrhea in 17 to 34 percent of patients, vomiting in 5 to 50 percent, and decreased appetite in 7 to 20 percent. Is this the same evidence that led to CBD’s FDA approval? No. FDA approval is based on randomized controlled trials measuring seizures in Lennox-Gastaut syndrome, Dravet syndrome, and tuberous sclerosis complex. This review looks at nonseizure outcomes in other, broader epilepsy populations. Does this review prove CBD improves cognition or behavior? No. Most included studies were observational, open-label, or retrospective with moderate to high bias risk, so the finding is a research signal rather than proof of benefit. Could the reported improvement come from something other than CBD directly? Yes. Some nonseizure improvement may reflect fewer seizures or reduced antiseizure medication burden rather than a direct effect of CBD on cognition or behavior. Does the review provide an effect size? No. Because study designs and outcome measures varied widely, the authors used narrative synthesis rather than statistical pooling, so no combined effect size is reported. What research is needed next? Prospective, controlled studies with standardized cognitive and behavioral measures, a defined comparator, and prespecified nonseizure endpoints are needed to test this signal rigorously. ### Related --- ### Verification & Medical Governance - **Lead Clinical Author:** Benjamin Caplan, MD - **Credentials:** Board Certified in Family Medicine (ABFM), 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).