THC reduced the brain's error-detection signal in healthy volunteers
After inhaling THC vapor, healthy volunteers showed a significantly reduced error-related negativity (ERN) brain signal, indicating impaired performance monitoring.
Quick Facts
What This Study Found
Ten healthy volunteers completed a speeded Flankers task (a test of accuracy under time pressure) after receiving THC or placebo vapor in a double-blind crossover design. EEG recordings showed the error-related negativity (ERN), a brain signal that fires immediately after making a mistake, was significantly reduced after THC.
Despite this reduced error-detection signal, behavioral performance on the task was not significantly different between THC and placebo conditions. This disconnect suggested THC impaired the brain's internal monitoring system without immediately degrading task performance in this simple paradigm.
This was the first study to directly demonstrate cannabinoid effects on the ERN.
Key Numbers
10 healthy volunteers. ERN was significantly reduced after THC compared to placebo. Behavioral accuracy on the Flankers task was not significantly different between conditions.
How They Did This
Double-blind, randomized, placebo-controlled crossover design. 10 healthy volunteers inhaled THC or placebo vapor. EEG was recorded during a speeded Flankers choice-reaction-time task. Error-related negativity was measured on error trials.
Why This Research Matters
Performance monitoring is essential for catching and correcting mistakes. A reduced ERN means the brain is less aware of its own errors, which could have implications for driving, complex decision-making, and other tasks where error detection matters.
The Bigger Picture
Reduced ERN is also seen in schizophrenia and other psychiatric conditions. This parallel between THC effects and psychosis-related brain changes added to the evidence linking cannabinoid system disruption to psychosis-relevant cognitive changes.
What This Study Doesn't Tell Us
Very small sample size (10 volunteers). Single acute dose design. The Flankers task was not optimized to detect behavioral effects. The disconnect between ERN reduction and preserved behavior might not hold in more demanding real-world tasks.
Questions This Raises
- ?Does chronic cannabis use permanently reduce the ERN?
- ?Would more complex tasks reveal behavioral consequences of impaired performance monitoring?
- ?Is the reduced ERN related to the subjective "not caring about mistakes" experience reported by cannabis users?
Trust & Context
- Key Stat:
- First study to show cannabinoid effects on error-related negativity
- Evidence Grade:
- Small RCT with 10 participants. First demonstration of its kind but underpowered for definitive conclusions.
- Study Age:
- Published in 2011. Subsequent studies have replicated and extended findings on cannabis effects on performance monitoring.
- Original Title:
- Acute effects of delta-9-tetrahydrocannabinol on performance monitoring in healthy volunteers.
- Published In:
- Frontiers in behavioral neuroscience, 5, 59 (2011)
- Authors:
- Spronk, Desirée, Dumont, Glenn J H, Verkes, Robbert J(2), de Bruijn, Ellen R A
- Database ID:
- RTHC-00525
Evidence Hierarchy
Participants are randomly assigned to treatment or placebo groups to test cause and effect.
What do these levels mean? →Frequently Asked Questions
Does THC make you worse at noticing your mistakes?
This study found THC reduced the brain's automatic error-detection signal. Participants did not perform worse on a simple task, but the reduced internal monitoring could matter for complex, high-stakes activities where catching errors quickly is important.
What is the error-related negativity?
The ERN is a brain wave that fires within 100 milliseconds of making an error, before you are even consciously aware of the mistake. It reflects the brain's automatic quality-control system. A smaller ERN means this system is less active.
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Cite This Study
https://rethinkthc.com/research/RTHC-00525APA
Spronk, Desirée; Dumont, Glenn J H; Verkes, Robbert J; de Bruijn, Ellen R A. (2011). Acute effects of delta-9-tetrahydrocannabinol on performance monitoring in healthy volunteers.. Frontiers in behavioral neuroscience, 5, 59. https://doi.org/10.3389/fnbeh.2011.00059
MLA
Spronk, Desirée, et al. "Acute effects of delta-9-tetrahydrocannabinol on performance monitoring in healthy volunteers.." Frontiers in behavioral neuroscience, 2011. https://doi.org/10.3389/fnbeh.2011.00059
RethinkTHC
RethinkTHC Research Database. "Acute effects of delta-9-tetrahydrocannabinol on performance..." RTHC-00525. Retrieved from https://rethinkthc.com/research/spronk-2011-acute-effects-of-delta9tetrahydrocannabinol
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.