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Keywords:

  • Cue exposure;
  • cue-reactivity;
  • craving;
  • relapse;
  • tolerance of discomfort;
  • urges to smoke

Sayette & Tiffany examine the methodology of measuring craving in cue exposure experiments and present an alternative to distinguishing between cue-induced and abstinence-induced craving [1]. They present the new concept of peak provoked craving (PPC), which combines the impact of cues to smoke and level of background craving. The approach avoids isolating different sources of craving and focuses instead on the most intense urge to smoke. Indeed, efforts to separate the craving caused by cues may, in many cases, be futile, as baseline ratings could be clouded by cues or subject to ceiling effects caused by abstinence. While the source of craving might be theoretically interesting, the PPC method would appear to be more clinically relevant; however, it is not difficult to think of circumstances under which baseline ratings need to be considered. For example, one abstinent smoker might have a baseline rating of 65 (on a scale of 0–100), which rises to 70 after cue exposure. Another smoker might, similarly, have a post-cue score of 70, but report a much lower baseline, for instance 10. Both smokers would have the same PPC score, which would mask important differences (see Fig. 1). The first individual does not appear to be influenced strongly by cues to smoke; rather, he/she is more prone to the effects of abstinence, while the second is affected primarily by smoking cues. It is likely that these two smokers would benefit from differing treatments.

figure

Figure 1. An illustrated example of differences in craving and tolerance of discomfort in two subjects

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Previously, Sayette and colleagues suggested an alternative approach [2], which combines baseline ratings and a ‘magnitude estimation’ of craving change. The latter requires smokers to compare their post-cue exposure urges to their baseline scores; for example, all baseline scores are given a numerical index of 10. If the post-cue urge increased by 50%, the magnitude estimation score would be 15. We believe a simplified form of magnitude could use subjective anchors that do not require numerical calculations by the participant; e.g. ‘Compared to baseline, is your urge to smoke now: much weaker, weaker, the same, stronger, much stronger?’.

One of the primary reasons for the proposal of PPC is that cue-reactivity has failed so far to demonstrate a clear relationship with such clinically meaningful outcomes as stopping smoking [3]. Sayette & Tiffany suggest that self-reported cravings might not be measuring much at all. Tiffany has described eloquently how craving might occur only when one tries to inhibit smoking [4]. There are countless anecdotal accounts of smokers lapsing ‘absent-mindedly’, presumably via an ‘automatic’ response to smoking cues. Even if cues do first trigger craving, smokers may attribute the decision to smoke to the presence of the cue, rather any craving it generated. In these circumstances, the measurement of craving would be uninformative.

The authors also discussed the concept of a threshold above which craving tips the balance in favour of smoking. To understand more clearly the relationship between craving and smoking, we may also have to consider the extent to which smokers can tolerate these PPC. Consider the example we have attempted to describe pictorially in Fig. 1, which uses the two smokers from our earlier example. Subject 1 has a much lower threshold for discomfort than subject 2, and would smoke when this threshold is crossed at the two time-points shown. Although subject 2 has, on several occasions, experienced a similar absolute level of craving to subject 1, he/she would not smoke, as his/her capacity to withstand this discomfort is at a sufficiently high level. In other words, the strength, or indeed frequency, of the urge to smoke on its own may not be enough to predict if they will smoke. This threshold may also vary within individuals.

Research into tolerance of discomfort and dependence began some 25 years ago. Hajek and colleagues demonstrated a significant correlation between tolerance of discomfort (endurance in breath-holding) and short-term smoking cessation outcome. Those with a higher tolerance of discomfort were more likely to quit smoking [5]. Others have demonstrated a similar relationship [6, 7].

The idea posed by Sayette & Tiffany of exposing smokers to extreme conditions in order to observe vulnerability is potentially of great clinical relevance. Resisting cravings requires mental and physical effort. Numerous factors might deplete this presumably limited reserve (e.g. stress, tiredness, withdrawal discomfort), and studies may be conceived in which one is ‘bombarded’ with a myriad of these reserve-lowering factors in order to explore the interplay between fluctuations in tolerance of discomfort and craving and smoking behaviour.

Building on the PCC model, we suggest that we need to help smokers to contextualize and quantify their craving. The subjective intensity and frequency of craving remains important, but if these current measurements of craving are considered alongside its tolerability then a stronger association between craving and smoking cessation might appear. In turn, this may help us to identify the best treatment options for people who smoke.

Declarations of interest

H.M. has received honoraria for speaking at research symposia and received benefits in kind and travel support from, and has provided consultancy to, the manufacturers of smoking cessation medications. O.W. has no conflicts of interest to declare.

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