Lennox-Gastaut Syndrome Diagnoses Spiked After FDA Approved CBD — Then Returned to Normal
New LGS diagnoses jumped nearly 60% after CBD was approved for the condition in 2018, suggesting some diagnoses may have been influenced by treatment availability rather than clinical criteria.
Quick Facts
What This Study Found
Annual LGS incidence rose ~30% from 2018 to 2019 and ~60% from 2017 to 2019, before returning to pre-approval baseline (2020-2023). This temporary spike occurred in temporal proximity to the 2018 FDA approval of CBD (Epidiolex) for LGS-associated seizures.
Key Numbers
Incidence rate: ~30% increase 2018-2019, ~60% increase 2017-2019. Returned to baseline 2020-2023. Temporal correlation with June 2018 FDA approval of Epidiolex for LGS.
How They Did This
Retrospective analysis computing annual new LGS diagnoses in the US from 2017-2023 using a large population-based electronic health record database.
Why This Research Matters
If new treatments drive diagnoses rather than the other way around, it undermines both clinical accuracy and research integrity. This pattern suggests some patients may have been labeled with LGS specifically to access CBD treatment.
The Bigger Picture
This is a cautionary tale about how treatment availability can distort diagnostic practices — relevant beyond just epilepsy, as new cannabis-based treatments for other conditions could create similar diagnostic inflation if criteria aren't strictly maintained.
What This Study Doesn't Tell Us
Administrative data with ICD codes cannot confirm diagnostic accuracy. Cannot prove causation between CBD approval and diagnosis increase. Multiple factors may have contributed. COVID-19 may have affected 2020-2021 diagnostic patterns. Insurance coding practices may have changed independently.
Questions This Raises
- ?Were the excess diagnoses actual LGS, diagnostic code updates, or misdiagnoses?
- ?Did patients who received expanded LGS diagnoses benefit from CBD treatment?
- ?Should approval of new treatments trigger enhanced diagnostic auditing?
Trust & Context
- Key Stat:
- Evidence Grade:
- Large population-based database provides reliable trend data, but administrative records cannot distinguish genuine incidence changes from coding practice changes.
- Study Age:
- Published 2026 analyzing 2017-2023 EHR data following 2018 Epidiolex FDA approval.
- Original Title:
- A temporary spike: Investigating Lennox-Gastaut syndrome incidence in the US following FDA approval of cannabidiol.
- Published In:
- Epileptic disorders : international epilepsy journal with videotape (2026)
- Authors:
- Marcinski Nascimento, Kaley J, Li, Yifan(2), Lin, Binx Y, Dixon-Salazar, Tracy, Perry, M Scott, Xu, Kevin Young, Nascimento, Fábio A
- Database ID:
- RTHC-08463
Evidence Hierarchy
Frequently Asked Questions
Did CBD approval change how often Lennox-Gastaut syndrome was diagnosed?
It appears so — new LGS diagnoses jumped about 60% in the year after CBD was approved for the condition, before returning to normal levels by 2020, suggesting some diagnoses may have been motivated by treatment access.
Were people being misdiagnosed to get CBD?
The study can't prove that, but the temporary spike and return to baseline strongly suggest that at least some of the increase reflected diagnostic practices influenced by treatment availability — including possible code updates and misdiagnosis of other severe epilepsies as LGS.
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Cite This Study
https://rethinkthc.com/research/RTHC-08463APA
Marcinski Nascimento, Kaley J; Li, Yifan; Lin, Binx Y; Dixon-Salazar, Tracy; Perry, M Scott; Xu, Kevin Young; Nascimento, Fábio A. (2026). A temporary spike: Investigating Lennox-Gastaut syndrome incidence in the US following FDA approval of cannabidiol.. Epileptic disorders : international epilepsy journal with videotape. https://doi.org/10.1002/epd2.70168
MLA
Marcinski Nascimento, Kaley J, et al. "A temporary spike: Investigating Lennox-Gastaut syndrome incidence in the US following FDA approval of cannabidiol.." Epileptic disorders : international epilepsy journal with videotape, 2026. https://doi.org/10.1002/epd2.70168
RethinkTHC
RethinkTHC Research Database. "A temporary spike: Investigating Lennox-Gastaut syndrome inc..." RTHC-08463. Retrieved from https://rethinkthc.com/research/marcinski-2026-a-temporary-spike-investigating
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.