Smoking, reward responsiveness, and response inhibition: tests of an incentive motivational model.

BACKGROUND: Incentive-motivation models of addiction suggest impairment of functional activity in mesocorticolimbic reward pathways during abstinence. This study tested implications for subjective and behavioral responses to nondrug incentives, cue-elicited craving, and prefrontal cognitive functions, particularly response inhibition.
METHODS: We tested 26 smokers after smoking and after overnight abstinence in counterbalanced order; 26 nonsmokers were also tested twice. Measures included a simple card-sorting test performed with and without financial incentive (the CARROT), the Snaith Hamilton Pleasure Scale as an index of subjective reward responsiveness, ratings of subjective craving and withdrawal before and after exposure to a cigarette, an index of oculomotor response inhibition (saccadic vs. antisaccadic eye movements), verbal fluency, and reversed digit span.
RESULTS: Compared with the smoking condition, and independently of withdrawal severity, abstinence was associated with reduced cue reactivity, pleasure expectancies, responsiveness to financial incentive, and response inhibition (antisaccadic eye movements). Verbal fluency and reversed digit span were unaffected, contrary to findings elsewhere with heavier smokers. Nonsmokers' scores either fell between those of abstainers and recent smokers or approximated those of recent smokers.
CONCLUSIONS: The data were in general consistent with behavioral predictions derived from the incentive-motivational model of addiction and suggest that abstinence may be associated with impairments of motivation and response inhibition, which are independent of other subjectively experienced withdrawal symptoms.