Impulsivity and response inhibition in alcohol dependence and problem gambling.
BACKGROUND
Impulsivity is a central feature of drug addiction and may arise as a result of impaired inhibitory control. The extent to which inhibitory deficits arise as a consequence of drug exposure or relate to pre-existing addiction vulnerability is unknown.


METHODS
This study compared measures of impulsivity in outpatients with alcohol dependence (n = 23) and problem gambling (n = 21), a putative behavioural addiction where direct effects of drug exposure may be minimal. Healthy controls (n = 27) were also tested, in a cross-sectional design. Subjects completed the stop-signal test as a neurocognitive probe of response inhibition, alongside self-report ratings of impulsivity, adult ADHD and OCD.


RESULTS
On the stop-signal test, Go reaction time and stop-signal reaction time were significantly slower in the alcohol-dependent group, compared with healthy controls. Healthy controls slowed their responding after successful and failed stop trials. Slowing after failed stop trials was significantly attenuated in the alcohol-dependent subjects. Go reaction time and post-error slowing were correlated with chronicity and severity, respectively, in the alcohol-dependent subjects. Problem gamblers did not differ significantly from controls on the stop-signal test, despite trait elevations in impulsivity ratings.


CONCLUSIONS
Inhibitory control is impaired in alcohol dependence but occurs in the context of psychomotor slowing. In addition, alcohol-dependent individuals failed to show behavioral adjustment following failed stops. These deficits may represent direct effects of chronic alcohol administration on fronto-striatal circuitry.
Lawrence
Andrew J
AJ
Behavioural and Clinical Neuroscience Institute, University of Cambridge, Cambridge CB2 3EB, UK.
Luty
Jason
J
Bogdan
Nadine A
NA
Sahakian
Barbara J
BJ
Clark
Luke
L
D000328:Adult; D000437:Alcoholism / Q000523:psychology*; D000704:Analysis of Variance; D002755:Choice Behavior / Q000502:physiology; D056344:Executive Function / Q000502:physiology; D005715:Gambling / Q000523:psychology*; D006801:Humans; D007175:Impulsive Behavior / Q000503:physiopathology* / Q000523:psychology*; D007266:Inhibition, Psychological; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D011237:Predictive Value of Tests; D011930:Reaction Time / Q000502:physiology; D012044:Regression Analysis; D012720:Severity of Illness Index