Active chronic cannabis users showed significantly impaired awareness of their own mistakes, associated with reduced activity in brain regions critical for error monitoring.
Read this if you use cannabis regularly and want to understand how it might affect your ability to self-monitor.
Cannabis users showed equivalent impulse control but significantly impaired error awareness
What the researchers found
Sixteen active chronic cannabis users and 16 controls performed a Go/No-go response inhibition task during fMRI scanning. The task measured both the ability to stop a response (inhibitory control) and awareness of errors when they occurred.
Cannabis users performed equally well at inhibiting responses, but they showed a significant deficit in awareness of their own commission errors.
This reduced error awareness was associated with reduced activity (hypoactivity) in the anterior cingulate cortex (ACC) and right insula, two brain regions critical for monitoring behavior and interoceptive awareness.
Increased hypoactivity in both regions significantly correlated with error awareness rates in the cannabis group but not in controls.
Why it matters
Error awareness is fundamental to self-monitoring and behavior change. A reduced capacity to notice mistakes could contribute to continued problematic behavior patterns, including ongoing drug use.
The numbers in context
16 cannabis users and 16 controls. Inhibitory control was equivalent between groups. Error awareness was significantly reduced in cannabis users. ACC and right insula hypoactivity correlated with error awareness deficits in the cannabis group.
How the study worked
Cross-sectional fMRI study comparing 16 active chronic cannabis users to 16 matched controls. Participants performed a Go/No-go task that separately measured inhibitory control and error awareness. Brain activation was measured with event-related fMRI.
What this study cannot tell us
Small sample (16 per group). Cross-sectional design cannot determine whether reduced error awareness preceded cannabis use or resulted from it. Participants were active users, so acute intoxication effects cannot be fully separated from chronic effects.
How to read the evidence
Small cross-sectional fMRI study (16 per group) that cannot establish causation or rule out pre-existing differences.
When this study was published
Published in 2009. Subsequent research has further explored cognitive monitoring deficits in cannabis users, generally supporting the finding of impaired metacognitive awareness.
The bigger picture
Diminished error awareness has been linked to loss of insight, delusions, and perseverative behavior in other psychiatric conditions. This finding suggests chronic cannabis use may affect the brain circuits underlying self-awareness and self-correction.
Questions still open
- Does error awareness recover with cannabis abstinence? Could impaired error awareness predict who develops problematic cannabis use? Is the effect specific to cannabis or common across substance use?
Common questions
What is error awareness and why does it matter?
Could this be why some people do not think cannabis affects them?
Read the original research
Impaired error awareness and anterior cingulate cortex hypoactivity in chronic cannabis users.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 34(11), 2450-8
Citation
Hester, Robert; Nestor, Liam; Garavan, Hugh. (2009). Impaired error awareness and anterior cingulate cortex hypoactivity in chronic cannabis users.. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 34(11), 2450-8. https://doi.org/10.1038/npp.2009.67
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