Impaired error awareness and anterior cingulate cortex hypoactivity in chronic cannabis users

Drug abuse and other psychiatric conditions (e.g., schizophrenia) have been associated with a diminished neural response to errors, particularly in the anterior cingulate cortex (ACC) thought critical to error processing. A diminished capacity for detecting errors has been linked to clinical symptoms including the loss of insight, delusions and perseverative behaviour. Sixteen active chronic cannabis users and 16 control participants were administered a Go/No-go response inhibition task during event-related fMRI data collection. The task provides measures of inhibitory control and error awareness. Cannabis users’ inhibitory control performance was equivalent to that of the control group, but the former demonstrated a significant deficit in awareness of commission errors. Cannabis users demonstrated a diminished capacity for monitoring their behaviour that was associated with hypoactivity in the ACC and right insula. In addition, increased levels of hypoactivity in both the ACC and right insula regions were significantly correlated with error awareness rates in the cannabis group (but not controls). These difficulties are consistent with previous reports of hypoactivity in the neural systems underlying cognitive control and the monitoring of interoceptive awareness in chronic drug users, and highlight the potential relationship between cognitive dysfunction and behavioural deficits that have the potential to contribute to the maintenance of drug abuse.