Altered Impulse Control in Alcohol Dependence: Neural Measures of Stop Signal Performance
Article first published online: 21 JAN 2009
Copyright © 2009 by the Research Society on Alcoholism
Alcoholism: Clinical and Experimental Research
Volume 33, Issue 4, pages 740–750, April 2009
How to Cite
Li, C.-s. R., Luo, X., Yan, P., Bergquist, K. and Sinha, R. (2009), Altered Impulse Control in Alcohol Dependence: Neural Measures of Stop Signal Performance. Alcoholism: Clinical and Experimental Research, 33: 740–750. doi: 10.1111/j.1530-0277.2008.00891.x
- Issue published online: 25 MAR 2009
- Article first published online: 21 JAN 2009
- Received for publication September 23, 2008; accepted November 24, 2008.
- Alcohol Abuse;
- Response Inhibition;
- Error Processing;
Background: Altered impulse control has been implicated in the shaping of habitual alcohol use and eventual alcohol dependence. We sought to identify the neural correlates of altered impulse control in 24 abstinent patients with alcohol dependence (PAD), as compared to 24 demographics matched healthy control subjects (HC). In particular, we examined the processes of risk taking and cognitive control as the neural endophenotypes of alcohol dependence.
Methods: To this end, functional magnetic resonance imaging (fMRI) was conducted during a stop signal task (SST), in which a procedure was used to elicit errors in the participants. The paradigm allowed trial-by-trial evaluation of response inhibition, error processing, and post-error behavioral adjustment. Furthermore, by imposing on the subjects to be both fast and accurate, the SST also introduced a distinct element of risk, which participants may or may not avert during the task. Brain imaging data were analyzed with Statistical Parametric Mapping in covariance analyses accounting for group disparity in general performance.
Results: The results showed that, compared to HC, PAD demonstrated longer go trial reaction time (RT) and higher stop success rate (SS%). HC and PAD were indistinguishable in stop signal reaction time (SSRT) and post-error slowing (PES). In a covariance analysis accounting for go trial RT and SS%, HC showed greater activity in the left dorsolateral prefrontal cortex than PAD, when subjects with short and long SSRT were contrasted. By comparing PAD and HC directly during stop errors (SE), as contrasted with SS, we observed greater activity in PAD in bilateral visual and frontal cortices. Compared to HC, PAD showed less activation of the right dorsolateral prefrontal cortex during PES, an index of post-error behavioral adjustment. Furthermore, PAD who showed higher alcohol urge at the time of the fMRI were particularly impaired in dorsolateral prefrontal activation, as compared to those with lower alcohol urge. Finally, compared to HC subjects, PAD showed less activity in cortical and subcortical structures including putamen, insula, and amygdala during risk-taking decisions in the SST.
Conclusion: These preliminary results provided evidence for altered neural processing during impulse control in PAD. These findings may provide a useful neural signature in the evaluation of treatment outcomes and development of novel pharmacotherapy for alcohol dependence.