Nicotine withdrawal and reward responsivity in a card-sorting task

Rationale  Animal studies have demonstrated decreased reward responsivity during nicotine withdrawal (e.g., Epping-Jordan et al., Nature 393:76–79, 1998) and the Card Arranging Reward Responsivity Objective Test (CARROT) has recently been used to study the effect of nicotine withdrawal on reward responsivity in humans (e.g., Al-Adawi and Powell, Addiction 92:1773–1782, 1997; Powell et al., Biol Psychiatry 51:151–163, 2002). We investigated a suggestion that nicotine withdrawal may have additional reward-related effects apart from the reward responsivity effects already observed. Objective  The objective of this study was to determine whether or not nicotine withdrawal results in slower improvements in performance on a card-sorting task over a series of trials. Method  We carried out two experiments using a modified version of the CARROT, the mCARROT, to compare the performance of human participants in nicotine withdrawal with those who were satiated. Results  Although withdrawal produced no direct effect on the mCARROT measure of reward responsivity, the overall sorting rate was lower, and the increase in sorting rate across successive trials was slower during nicotine withdrawal than during satiation. Conclusions  These data indicate that nicotine withdrawal impacted on task performance independently of the introduction of a performance contingent reward, suggesting a novel reward-related effect of nicotine withdrawal.