Cognitive Effects of Cigarette Deprivation and Quit Status

Objectives: To study the impact of substance deprivation on a range of cognitive tasks, and compare the effects of imposed deprivation with self-imposed quit attempts. Design: 20 non-smokers, 10 continuing smokers, 13 recently quit smokers and 10 smokers deprived of cigarettes for 12 hours. Method: Participants completed a modified Stroop task (23 smoking and 23 neutral words), a single stimulus pictorial dot probe (ten neutral and five smoking stimuli, presented twice as valid cues and twice as invalid cues), a sustained attention task (respond to eighteen neutral target words, but not to ‘cathedral’ and ‘cigarette’) and a word generation task (name as many relaxation-related words as possible in two minutes). Ratings of mood and intrusive thought frequency were also collected, before and after the cognitive tasks. Results: Deprived and quit smokers showed similar biases compared with non-smokers and continuing smokers, on colour naming of smoking words and smoking word generation. Only the quit smokers showed a difficulty disengaging from a smoking picture on the singlestimulus dot probe. No effects on sustained attention were observed. Increases in smoking thoughts over the session were associated with worsening mood, but were not correlated with smoking-related biases on the cognitive tasks. Stroop and dot probe interference were not significantly correlated, but dot probe interference was associated with worsening mood and greater smoking word generation. Conclusions: Cognitive effects of smoking deprivation are multifactorial, and may be due to greater availability of target-related information as well as to controlled processing in craving. (246 words) Cognitive Effects of Cigarette Deprivation: 3 Many readers of this paper will right now be in an environment where they are not able to smoke. Now that we have mentioned this fact, they may well be thinking about having a cigarette. Dealing with the intensity of fleeting urges is bad enough. What can be especially difficult is the tendency for the thoughts to grab and keep attention, so that other tasks—like reading and thinking about this paper—become much more difficult to do. There has been a recent resurgence of interest in the phenomenon of craving, and an increased interest in the cognitive interference that craving appears to invoke. Much of this work has been inspired by the theory of Tiffany (1990), which holds that craving involves controlled cognitive processing, which then competes with other tasks. Existing research tends to confirm Tiffany’s contention (Kavanagh, Andrade, & May, under review). Most of this evidence involves tasks that have direct competition between stimuli that relate to the appetitive target and those that do not. One such task is a modified Stroop colour naming task (Stroop, 1935), in which colour naming of words is slower when the words are related to the target (Channon & Hayward, 1990; Ogden & Greville, 1993). Two studies have found this effect among smokers deprived of cigarettes for 12 hours (Gross, Jarvik & Rosenblatt, 1993; Mogg & Bradley, 2002). The latter study also found that, unlike many studies of preferential processing of anxietyrelated stimuli by anxious people, there was no preattentional smoking Stroop effect (using a masked version of the task). Further research has begun to disentangle the multiple processes that may underlie effects from an unmasked modified colour naming task. A Dot Probe task offers a way of testing the contribution of attentional bias. In such tasks, participants respond to the location of a dot (e.g. left or right) as fast as they can. In the standard competitive stimulus dot probe, the dot is preceded by a stimulus on each side, one of which is related to the appetitive target, one of which is not. An attentional bias is reflected by a faster response to the dot when it is presented on the same side as the appetitive target. Verbal dot probe tasks have been successfully used during food deprivation (Mogg, Bradley, Hyare & Lee, 1998), and with abstaining alcoholics (Stormarck, Field, Hugdahl, & Horowitz, 1997). In smokers, a pictorial Cognitive Effects of Cigarette Deprivation: 4 version of the dot probe has shown faster reaction times to smoking pictures by current smokers than by non-smokers, with former smokers having intermediate effects (Ehrman, Robbins, Bromwell et al., 2002). A similar task has shown a greater bias with light smokers than with either heavy smokers or non-smokers (Mogg, Bradley, Duka and Dickenson; 2003), a result that is interpreted as reflecting a more positive response to the smoking stimuli in light smokers. Furthermore, smokers who have made multiple attempts to quit are more prone to the attentional bias than those who have not (Mogg, Wright, & Field, 2003). Smokers have stronger preferences for smoking-related pictures than do non-smokers, asnd eye movement measures show a longer duration of attention than to control pictures (Mogg, Bradley, Field, & De Houwer, 2003). The dot probe effect with smokers that is obtained with 500ms duration is maintained when the pictures are presented for as long as 2000ms (Mogg, Wright, & Field, 2002; Mogg, Bradley, Field, & De Houwer, 2003). When smokers are deprived of cigarettes for 12hr they have a greater attentional bias for smoking pictures than when they are not smoking deprived (Mogg & Bradley, 2002), and a longer attentional fixation on smoking stimuli by smokers is positively correlated with their urge to smoke (Mogg, Bradley, Field, & De Houwer, 2003). Together, these results strongly support the notion that craving for cigarettes does have an impact on attentional deployment and suggest that the pictorial smoking dot probe effects are well established. A question remains whether the attentional effect is so powerful that it interferes with disengagement from a sole picture (rather than only occurring in the context of pictorial competition). Further questions can be raised about other potential cognitive effects from craving. While Mogg and Bradley (2002) did not find a preattentional effect on a masked smoking Stroop, further work is needed on whether the effects of craving are restricted to controlled processing—as Tiffany’s theory predicts—or whether the appetitive targets are more Cognitive Effects of Cigarette Deprivation: 5 cognitively available, reflecting a bias in automatic processing. This would be consistent with competing approaches, such as the neuroadaptational incentive sensitization theory of Robinson and Berridge (1993) and the memory association hypothesis of Stacy (1995). There is some evidence in favour of an association effect with other appetitive targets. Stacy (1995, 1997) found that target-related memory associations occur more often in more frequent users of alcohol and marijuana, and furthermore, that the number of associations was a better predictor of subsequent use than explicit expectancies. We know of no such test in people who are deprived of an appetitive target, or an explicit attempt to link such associations with craving. If craving selectively enhances recall for past drug use episodes, then memory retrieval for non-target information may be disrupted during craving episodes, and the persistent retrieval of drug related information may prolong the experience of craving. Attention is not a unitary phenomenon, and another potential area of cognitive interference would be vigilance tasks which require people to sustain attention and suppress automatic responses. Higher levels of deprivation or craving may be associated with a greater difficulty in inhibiting rapid responses to target stimuli than to other material. One task which may be able to test this hypothesis is the Sustained Attention to Response Task (SART; Robertson, Manly, Andrade, Baddeley & Yiend, 1997). This task requires people to respond as quickly as possible with a button press upon a computerised presentation of an integer, but to withhold responses to an infrequent target (the integer 3). The task, which measures ability to use controlled processing to override automated responses, is sensitive to brain injury (Robertson et al., 1997) and to attentional disruption in people with schizophrenia (Oram et al., 2001). In the current study, we use a modification of the SART using both non-smoking and smoking words, to look for a differential response suppression in craving for cigarettes. Since this task has never been previously used in craving research, our application of it here was purely speculative, but was intended to explore the generality of the effects of craving on attention. Finally, there is a need to test whether target-related biases as detected by different methods correlate with each other, or represent different interference processes. Mogg and Bradley (2002) did not find a significant positive correlation between smoking versions of the Cognitive Effects of Cigarette Deprivation: 6 visual dot probe and modified Stroop, suggesting that craving might be impacting several different cognitive processes. Further investigations with a wider set of tasks is required. The present study investigated the specific effects of craving on cognitive processes. In common with several previous studies, we used an experimentally deprived group, but we also included a group of smokers who had recently quit. This enabled us to directly test the distinction between externally imposed versus self-imposed deprivation, a factor that has not been directly tested in a single smoking study. While Tiffany (1990) makes the distinction between the two types of craving (i.e., craving caused by unavailability of target versus craving caused by response inhibition), he does not predict whether the extent of cognitive disruption depends on type of abstinence. If quit smokers had higher levels of smoking thoughts or were actively trying to suppress thoughts, they would presumably portray more prominent deficits in attention