A double-blind placebo-controlled experimental study of nicotine: II--Effects on response inhibition and executive functioning.
BACKGROUND
Smokers may show abnormal functioning in prefrontal cortex during acute abstinence, reflecting deficient activity in mesocorticolimbic circuitry. Cognitive correlates of this putatively include impaired response inhibition and other aspects of executive functioning.


OBJECTIVE
To investigate whether inhibitory control and other executive functions in smokers are impaired during acute abstinence relative to post-nicotine.


METHODS
145 smokers were tested twice after overnight abstinence-once after nicotine and once after placebo lozenges (order counterbalanced, double-blind)-on an antisaccade task, a continuous performance task (CPT), a delayed response spatial working memory task and a verbal fluency test.


RESULTS
Compared with placebo, nicotine was associated with better inhibitory control on the antisaccade task and fewer impulsive responses to filler stimuli (motor errors) on the CPT; at the first assessment only, nicotine also reduced impulsive responses to 'catch' stimuli on the CPT. However, it did not affect CPT response bias (an index of impulsive vs cautious decision-making), spatial working memory, or verbal fluency.


CONCLUSIONS
Smoking abstinence appears to be associated with a difficulty in inhibiting prepotent motor responses, and with nicotine to attenuate this difficulty. However, more 'cognitive' forms of inhibitory control (e.g. decision-making) and the other aspects of executive function tested here appear to be unaffected.
Dawkins
Lynne
L
School of Psychology, University of East London, Romford Road, Stratford, London, E15 4LZ, UK. L.E.Dawkins@uel.ac.uk
Powell
Jane H
JH
West
Robert
R
Powell
John
J
Pickering
Alan
A
D000328:Adult; D000339:Affect / Q000187:drug effects; D016739:Behavior, Addictive; D003657:Decision Making / Q000187:drug effects; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008568:Memory / Q000187:drug effects; D008606:Mental Processes / Q000187:drug effects*; D008875:Middle Aged; D009048:Motor Skills / Q000187:drug effects; D009538:Nicotine / Q000494:pharmacology*; D018722:Nicotinic Agonists / Q000494:pharmacology*; D011930:Reaction Time / Q000187:drug effects; D012438:Saccades / Q000187:drug effects; D012907:Smoking / Q000009:adverse effects*; D013375:Substance Withdrawal Syndrome / Q000523:psychology*; D014705:Verbal Behavior / Q000187:drug effects
D018722:Nicotinic Agonists; D009538:Nicotine