# 5 Huge Flaws in Cannabis and Brain Function Research

> **Author:** Benjamin Caplan, MD (ABFM Board Certified, MA Lic. #240562, NPI: 1962722637)
> **Publisher:** CED Clinic (https://cedclinic.com)
> **Canonical URL:** https://cedclinic.com/cannabis-and-brain-function-study-flaws/
> **Published:** 2025-02-06T00:30:19-04:00 | **Last Modified / Clinically Audited:** 2026-09-27T21:08:57-04:00
> **Clinical Summary:** New study claims cannabis harms brain function—but does it hold up? I unravel 5 huge flaws in this research and what it really means for your mind.

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Table of Contents

- [Are We Really Seeing Damage—Or Just Bad Science?](#Are_We_Really_Seeing_DamageOr_Just_Bad_Science)
- [1. Correlation Is Not Causation (But It Sure Sells Headlines)](#1_Correlation_Is_Not_Causation_But_It_Sure_Sells_Headlines)[Why This Is a Problem for Cannabis Research:](#Why_This_Is_a_Problem_for_Cannabis_Research)
- [The Cannabis Conundrum: Science, Stigma, and the Battle Against Bias](#The_Cannabis_Conundrum_Science_Stigma_and_the_Battle_Against_Bias)[Why Does This Matter?](#Why_Does_This_Matter)
- [ ](#i)
- [The Missing Education: Why Doctors Know Next to Nothing About Cannabis](#The_Missing_Education_Why_Doctors_Know_Next_to_Nothing_About_Cannabis)
- [Who Controls the Narrative? Follow the Money](#Who_Controls_the_Narrative_Follow_the_Money)
- [ ](#i-2)
- [ ](#i-3)
- [2. The Definition of “Heavy Use” Is Totally Arbitrary](#2_The_Definition_of_8220Heavy_Use8221_Is_Totally_Arbitrary)[What’s Wrong With This?](#Whats_Wrong_With_This)
- [3. No One’s Talking About CBD—And That’s a Huge Mistake](#3_No_Ones_Talking_About_CBDAnd_Thats_a_Huge_Mistake)[What This Study Gets Wrong:](#What_This_Study_Gets_Wrong)
- [Final Thoughts](#Final_Thoughts)[Related](#Related)

## Are We Really Seeing Damage—Or Just Bad Science?




 



 





 




If you’ve read the headlines lately, or for the 4.4 million people who saw[Huberman’s tweet](https://x.com/hubermanlab/status/1886875042098897183?s=46), you’d think cannabis users are one hit away from forgetting their own names. Studies claim **cannabis impairs brain function**, **wrecks memory**, and **shrinks gray matter like a raisin in the sun**.




 




But hold up—**how reliable is this research, really?**




 





 




[More access here](https://cedclinic.com/)claims that **heavy cannabis use is linked to lower brain activation during working memory tasks**. Sounds alarming. But before we all start panic-quit puffing, allow me to help you take a hard look at **five serious flaws** in how [cannabis and brain function](https://cedclinic.com/the-endocannabinoid-system-controls-various-functions-of-the-olfactory-circuit/) research is done—and why **the truth is far more complicated than these headlines suggest**.



 




## 1. Correlation Is Not Causation (But It Sure Sells Headlines)




 



 




Most cannabis and brain function studies are **cross-sectional**, meaning they take a single snapshot in time. Imagine looking at a photo of someone drenched in water and declaring, **“They must have jumped into a pool!”** Maybe. But maybe it was rain. Maybe they spilled their drink. Maybe they just sweat a lot.




 


 [https://cedclinic.com/cannabis-and-brain-function-study-flaws/screenshot-2025-02-05-at-11-27-36-pm/](https://cedclinic.com/cannabis-and-brain-function-study-flaws/screenshot-2025-02-05-at-11-27-36-pm/) [https://cedclinic.com/cannabis-and-brain-function-study-flaws/screenshot-2025-02-05-at-11-27-46-pm/](https://cedclinic.com/cannabis-and-brain-function-study-flaws/screenshot-2025-02-05-at-11-27-46-pm/) [https://cedclinic.com/cannabis-and-brain-function-study-flaws/screenshot-2025-02-05-at-11-27-53-pm/](https://cedclinic.com/cannabis-and-brain-function-study-flaws/screenshot-2025-02-05-at-11-27-53-pm/) [https://cedclinic.com/cannabis-and-brain-function-study-flaws/screenshot-2025-02-05-at-11-28-00-pm/](https://cedclinic.com/cannabis-and-brain-function-study-flaws/screenshot-2025-02-05-at-11-28-00-pm/) [https://cedclinic.com/cannabis-and-brain-function-study-flaws/screenshot-2025-02-05-at-11-28-10-pm/](https://cedclinic.com/cannabis-and-brain-function-study-flaws/screenshot-2025-02-05-at-11-28-10-pm/) [https://cedclinic.com/cannabis-and-brain-function-study-flaws/screenshot-2025-02-05-at-11-27-28-pm/](https://cedclinic.com/cannabis-and-brain-function-study-flaws/screenshot-2025-02-05-at-11-27-28-pm/) 


[Photo Credit](https://medium.com/swlh/a-visualization-correlation-vs-causation-d86d02b1042c)



### Why This Is a Problem for Cannabis Research:



 



Although the authors of the work, and the editors of the magazine that gets lots of press, would love for you to let them do the thinking for you, we don’t know **if cannabis use caused brain changes **or if people with certain brain differences were **more likely to use cannabis in the first place**.



 



Did **other factors (stress, genetics, environment, diet, sleep habits)** play a bigger role? We don’t know—because this kind of study **can’t tell us**. Brain activation differences don’t automatically mean **damage**—sometimes they mean **efficiency**. Lower activation could just mean the brain is working **smarter, not harder**.



 



?

**Better Science:** **Longitudinal studies** that track individuals before they start using cannabis and monitor changes over time. Until then, it’s all just educated guesswork.



 






 



## The Cannabis Conundrum: Science, Stigma, and the Battle Against Bias



 



 



There’s a reason why [cannabis research](https://cedclinic.com/pediatric-cannabis-certification-care-children/) often reads like a *scripted episode of Reefer Madness*, and it has little to do with the plant itself. Unlike pharmaceuticals with billion-dollar research budgets and legions of lobbyists, cannabis is a **natural medicine** that, by its very nature, threatens entrenched industries—from **Big Pharma to Big Alcohol to Big Tobacco**.



 



Let’s be clear: **there’s no money in proving cannabis is safe**. There’s no financial incentive for massive, multi-center trials to validate its therapeutic potential the way there is for, say, the next blockbuster psychiatric drug. The machine that funds research **thrives on patentable, synthetic compounds**—not a plant that anyone can grow.



 



 



### Why Does This Matter?



 



 



Because in **real, honest science**, you don’t set out to *prove* a position—you set out to **explore** a hypothesis. Yet, the **lopsided cultural bias against cannabis** means that most studies don’t ask:



❌ *“How can cannabis be safely incorporated into medicine?”*



❌ *“What populations might benefit the most?”*



❌ *“What are the full mechanisms—both harms and benefits—of cannabinoids in the brain?”*



 



Instead, the dominant research questions tend to sound more like:



✅ *“How does cannabis impair brain function?”*



✅ *“How addictive is cannabis?”*



✅ *“What are the risks of long-term cannabis use?”*



 



Do you see the problem? **If you only look for harm, you will find it.** That’s confirmation bias at its finest. And it’s precisely why cannabis science demands **extra skepticism**.



 



 




### 



###  



### The Missing Education: Why Doctors Know Next to Nothing About Cannabis



 



 



Ask the average physician how cannabis interacts with the **[endocannabinoid system](https://cedclinic.com/endocannabinoid-system-fear-extinction/)**—the regulatory network that influences **pain, mood, immune function, and cognition**—and you’ll likely get a blank stare.



 



Why? Because **cannabis is not taught in medical school**.



 



That’s right—while future doctors get **hundreds of hours of training** on **opioids, antidepressants, and every manner of synthetic pharmaceutical**, they receive next to nothing on **the body’s own cannabinoid system**—a system that literally every human being has. The irony? We teach doctors **about the opioid receptors but not about the cannabis receptors**, even though one class of drugs is fueling an overdose epidemic and the other has never killed anyone.



 



This blind spot in education has consequences:



 



**Doctors default to outdated, prohibition-era myths about cannabis.**



 



**Medical professionals rely on research that is often biased against cannabis from the start.**



 



**A plant with thousands of years of therapeutic history is treated like a fringe drug instead of an area of legitimate study.**



 



This isn’t just a research gap—it’s a **systemic failure in modern medicine**.



 




### Who Controls the Narrative? Follow the Money



 



 



Let’s not pretend that **science operates in a vacuum**. The way research is conducted, funded, and reported is **deeply political and profit-driven**.



 



Consider this:



**Pharmaceutical companies fund the majority of [medical research](https://cedclinic.com/cb2-receptor-agonist-parkinsons/).** Their goal? **Return on investment**, not necessarily objective truth.



**Cannabis poses a direct threat to billion-dollar industries**, including painkillers, sleep aids, antidepressants, and alcohol.



**Corporate interests control media narratives.** If a study suggests cannabis is harmful, it’s a headline. If a study suggests benefits? It’s buried in academic journals with no media coverage.



 





 



So when you see a **big, bold claim about cannabis harming the brain**, ask yourself:



 



**Who funded this research?**



 



**What’s the study’s real mission?**



 



**Why isn’t the full picture—including benefits—being reported?**



 



Because in honest science, you **don’t get clickbait headlines making sweeping declarations**. You get nuance. You get **careful, measured exploration**. And you get **a fair read of both sides of the evidence**.



 



If we don’t demand **critical thinking** in how we interpret cannabis research, we’re not just failing the plant—we’re failing science itself.



 




## 



##  




##  



## 2. The Definition of “Heavy Use” Is Totally Arbitrary



 



 



This study divides cannabis users into:



 



✅ **Nonusers** (<10 lifetime uses)



 



✅ **Moderate users** (10–999 uses)



 



✅ **Heavy users** (>1000 uses)



 



 



Hold on—**who decided that 1000+ uses is “heavy”?** And does **999 uses** magically mean your brain is fine, but **1001 uses** turns it into mashed potatoes?



 




 




### What’s Wrong With This?



 



 



It **ignores potency**—smoking low-THC cannabis daily for 20 years isn’t the same as dabbing 90% THC concentrate weekly.



 



It **ignores consumption method**—smoking, vaping, and edibles all **affect the brain differently**.



 



It **lumps all users into broad categories** without considering **frequency, dose, or duration**.



 



?

**What We Need Instead:** Studies should analyze **THC levels, consumption method, and long-term patterns**, not just slap users into vague categories.



 



 




## 



 



## 3. No One’s Talking About CBD—And That’s a Huge Mistake




 




Cannabis isn’t just THC. **CBD (cannabidiol)** is its quieter, more responsible sibling—one that might actually **protect the brain**.



 



### What This Study Gets Wrong:



 



 



It **doesn’t separate** high-THC users from those using **CBD-rich cannabis**.



 



**CBD has neuroprotective properties**, meaning it might actually **counteract some of THC’s negative cognitive effects**.



 



The real question isn’t just **“Does cannabis affect brain function?”** but **“How do different [cannabis compounds](https://cedclinic.com/cannabis-terpene-synergy-entourage-effect/) impact cognition?”**



 



?

**A Smarter Approach:** Future studies should compare **THC-heavy vs. CBD-rich cannabis** to get a clearer picture.



 



 




## Final Thoughts



 



 



Look, **cannabis isn’t a free pass to a sharper brain**, but these studies don’t prove it’s frying your neurons either. What they **do prove** is that **we need better research**—studies that actually control for variables, track long-term use, and separate correlation from causation.



 



?

**Bottom Line:**



 



✅ **One study isn’t proof**—we need long-term research before making the types of bold claims made here.



 



✅ **CBD vs. THC matters**—they have vastly different effects.



 



✅ **Brain activation changes ≠ permanent damage**—context matters.



 



✅ **Consider the full picture**—lifestyle, stress, and withdrawal effects play a huge role.



 



Want more *actual science* on cannabis? **[Join me on my newsletter](http://bit.ly/CaplanSubstack)** and keep the wool from your eyes!




 



 




 



 

### Related

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### 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).