Individual differences in difficulty quitting smoking

British Joumal of Addiction (1991) 86, 555-558 Individual differences in difficulty quitting smoking PETR HAJEK ICRF Health Behaviour Unit, Institute of Psychiatry, 101 Denmark Hill, London SES 8AP, UK Abstract This essay comments on the main approaches to studying individual differences in ability to quit smoking, and suggests complementing them with a concept of 'difficulty of quitting'. Several areas of research into determinants of ability to quit smoking are discussed, including measures of dependence, reactivity to nicotine, severity of withdrawal symptoms, endurance of discomfort, and psychological well being. A number of correlates of inability to quit may have a common denominator in stress and neuroticism. If these are the primary obstacles to quitting, changes in the composition of the smoking population and in the image of smoking can be expected which could lead to smoking losing some of its appeal for potential new recruits. Introduction After the second world war, the majority of the male population of Great Britain and the USA smoked. Smoking was a 'normal' male behaviour and as such it did not invite the types of question which are emerging now. In the 'normal people smoke' days, one would probably be more interested in examining the pathology of non-smokers. (Incidentally, when smoking prevalence was at these high levels, the peculiarity of non-smoking was emphasized by the fact that neither Hitler nor Mussolini smoked, while Stalin, Roosevelt and Churchill did.) When there was no reason not to smoke, the most interesting behavioural difference between smokers, the ability to quit, was almost totally invisible. Currently in Western developed countries most smokers want to quit. The question of why some succeed (with varying degrees of subjective difficulty), while others do not, is increasing in importance. If current trends continue, smoking in developed countries may become primarily the domain of those who cannot quit. If the hypotheses at the end of this paper are justified, difficulty of quitting will emerge as being determined primarily by variables pertaining to psychological health. Smoking will then adjoin the field of drug abuse, in as much as some kind of psychosocial pathology will be seen as an almost inevitable accompaniment of regular use. The 'normal people don't smoke' era will dawn. Approaches to studying individual differences in ability to quit smoking Two main contexts in which individual differences in quitting smoking have been discussed so far are the concept of dependence, and theories of relapse. They are associated with different models of determinants of success or failure in quitting smoking. In a sense, inability to quit constitutes the core of the concept of dependence. Under this view, the assertion that inability to quit is determined by degree of dependence is a tautology; dependence and inability to quit being essentially synonymous. Current work on dependence however often concentrates on mapping its hypothetical biological 555

556 Fetr Hajek causes such as nicotine tolerance and withdrawal. Variables such as endurance of discomfort or neuroticism are usually not part of the agenda. There is also a tendency to treat dependence as if it were the same as level of intake of nicotine. Thus questionnaire measures of dependence which show only small and inconsistent relationships with various indices of difficulty of quitting (Hughes et al, 1990) tend to be considered as validated if they relate satisfactorily to biochemical measures of nicotine intake. Theories of relapse are another area where individual differences in ability to quit smoking have been examined. As a single observable event, relapse invites enquiry into its immediate causes rather than into some general individual vulnerability, and the currently prevailing approaches emphasize situational and cognitive factors, rather than more enduring dispositions (Sutton, 1989). A strong theoretical perspective can limit the field of enquiry, and affect the interpretation of data. See for instance the literature on self-efficacy. Measures of self-efficacy taken post-treatment correlate with relapse in the near future, but pre-treatment measures in general do not (Sutton, 1989). Thus the post-treatment correlations may be caused by subjects accurately supposing that the degree of difficulty which they have experienced so far is indicative of the degree of difficulty to come. Yet the findings tend to be interpreted as showing that selfefficacy, rather than enduring difficulty of not smoking, determines relapse. Perhaps the relevant individual differences should be considered in terms of a concept such as 'difficulty of quitting, which would be less theoryladen. While the question of causes of dependence tends to implicate biological factors, and the question of causes of relapse suggests immediate antecedents, asking about causes of difficulty of quitting (or difficulty not smoking) could lead to a more open enquiry. It could also help communication, as there is currently no simple term for general use in this context. For instance, infiuences on an attempt to stop smoking of factors such as stress or depression might be better described as affecting difficulty of quitting rather than dependence or probability of relapse. Difficulty of quitting could be seen as encompassing both outcome of an attempt to stop smoking, and the accompanying subjective experience. To operationalize the term, e.g. as a subjective rating, would narrow it, but it could serve other useful functions. Most data on individual differences in quitting smoking come from studies of predictors of treatment outcome and of relapse, and from comparisons of smokers with ex-smokers. This usually leads to smokers being dichotomised into those who quit and those who did not. This dichotomy may obscure some facets of the problem. There may be advantages to complementing the perspective of success and failure with difficulty of quitting as a quantitative subjective variable. The concept of difficulty of quitting smoking (whether in a broad or narrow sense) may provide a complementary frame of reference for considering relevant individual differences. For instance, thinking about quitting smoking in terms of difficulty of quitting invites questions such as how smokers differ in the types of difficulty they encounter (e.g. in their withdrawal phenomenology); what causes these differences; how they are related to outcome in quitting smoking; whether and how difficulties vary at different stages of abstinence; how is difficulty of stopping smoking related to difficulty of staying quit, etc. One question of great importance is the stability of 'difficulty of quitting'. The concept of dependence implies that it is a more stable characteristic than according to current theories of relapse or stages of the smoking career. More research is needed to provide the answers. Further questions on difficulty of quitting suggest themselves. If it is a relatively stable characteristic, would it be an indicator of some general susceptibility to dependency ('addictive personality')? Drug users and alcoholics are very likely to smoke cigarettes, but so are prisoners, schizophrenics, and Spanish physicians. The relevant question is whether drug users and alcoholics find quitting tobacco more difficult than other comparable smokers. Some possible sources of individual differences in ability to quit smoking One of the main determinants of stopping smoking is obviously motivation to quit. The term 'ability to quit' is meant to imply concern with differences between individuals assumed to be matched for their motivation. Future research can be expected to continue to tackle a number of issues at various levels of proximity to quitting behaviour, ranging from differences in nicotine pharmacodynamics to situational influences. It may be that ability to quit will emerge as having a complex set of determinants, but it is also possible that several areas will be found to be interrelated and the problem simplified. The

Individual differences in difficulty quitting smoking 557 following comments concern only some of the areas of potential importance. The most explored predictors of ability to quit so far have been nicotine intake and previous experience of abstinence. They are often put together under the label of dependence (Fagerstrom & Schneider, 1989; West & Russell, 1985). Overall, the usual unexciting finding is that heavy smokers who say that they generally cannot manage without cigarettes find quitting on a particular occasion more difficult. However, the correlations involved are typically rather small. New measures of dependence (in sense of predictors of ability to quit) which incorporate some of the areas covered below as well as some attitudinal and motivational factors are likely to emerge in future. Reactivity to nicotine. Individual differences in reactivity to nicotine may influence difficulty in stopping smoking. For instance, subjective and heart rate reactions to the first cigarette after 24 hour abstinence seem to be related to withdrawal severity (West & Russell, 1988). At a behavioural level, individual differences in responses to nicotine are being explored for example by studies of long-term users of nicotine chewing gum (Hajek et al., 1988) or by newly emerging research on very light smokers (Shiffman, 1989; Shiffman et al., 1990; Hajek & West, 1989). Stable very light smokers are rare (the first tentative longitudinal data are only now emerging), and they seem to obtain similar nicotine exposure per cigarette as other smokers. Looking at how they react to nicotine, and what protects them from escalation to 'normal' heavier smoking, may contribute to explanations of individual differences in ability to quit smoking. Severity of withdrawal. Withdrawal discomfort is generally considered a major obstacle to quitting. Treatments, especially pharmacological ones, are often aimed explicitly at alleviating withdrawal. Measures of withdrawal discomfort seem to be close to directly measuring difficulty of quitting. Yet, for a while it seemed that severity of withdrawal was unrelated to outcome of an attempt to quit smoking (Hughes et al, 1990). Recent studies showed that the two may be related, although not closely (West et al, 1989; Hajek & West, in press), and more prospective studies of such relationships are needed. 'Withdrawal discomfort' is a composite phenomenon and contributions of its various parts need to be explored, together with their causes. Subjective ratings of withdrawal are probably a mixture of objective neurophysiological changes, and the way an individual handles the discomfort which they cause. If we were able to disentangle these two components, the second could well emerge as being at least as important for continuing abstinence as the first. Endurance of discomfort. In drug abuse and alcoholism, much speculative attention has been given to the concept of self-control, but most research data available seem to concern a so far rather unproductive issue of locus of control (Szara, 1986). The general public seems quite sure that quitting smoking is a question of'willpower'. Lack of willpower in this context apparently stands for giving in easily when the struggle gets unpleasant. Low endurance of discomfort seems to be an important part of the picture. There is a possible new opening in exploring this association in the finding that breathholding endurance may predict short-term outcome of an attempt at quitting smoking (Hajek et al, 1987). Breath holding has been shown to be a valid measure of endurance of physical discomfort (Hajek, 1989). Resisting withdrawal discomfort and holding one's breath or maintaining a hand grip might involve similar subjective criteria of what is unbearable and when to stop trying. If endurance of discomfort is related to sensitivity to withdrawal and to likelihood of relapse, it could be relevant to other addictions as well. Psychological well being. Success in quitting smoking seems to be related to 'psychosocial assets' (Ockene et al, 1982) such as good psychological health and supportive family background. The level and appraisal of stress (Ockene et al, 1982; Cohen, 1986), coping skills and strategies (Kamarck & Lichtenstein, 1988), and psychiatric morbidity (Hughes et al, 1986) seem to be important. More data are needed on most of these issues, but there are persuasive theoretical arguments for these connections. A number of theories of smoking which focus on the association between smoking and stress, imply a positive correlation between difficulty of quitting and stress or neuroticism (e.g. Ockene et al, 1981; Grunberg & Baum, 1985; Pomerlau, 1986; Warburton, 1990). The simplest hypothetical connection would be based on the assumption that smoking helps coping with negative states. In that case, more stressed and neurotic smokers should appreciate smoking more, smoke more often, and find quitting more difficult. This is even before any physical addiction is considered.

558 Petr Hajek After quitting, tobacco withdrawal may magnify the now exposed original discomfort, perhaps proportionally to the relief smoking used to provide, and future stress may evoke conditioned urge to smoke. Such arguments seem to provide a common denominator of a number of correlates of quitting, including psychological well being, smoke intake, withdrawal severity, and endurance of discomfort. (The sum total of discomfort associated with abstinence, and endurance of discomfort, could also be considered as independent contributors in a twofactor model of ability to quit smoking.) They present at best only a rough picture in need of much data, but they lead to a variety of testable hypotheses. To return to the theme of the introduction, if stress and neuroticism prevent quitting, the composition of the smoking population in countries where people want to quit may be shifting accordingly; and the image of smoking in the eyes of children could eventually change from a grown-up, rebellious or daring activity to a sign of inadequacy. In this scenario a new approach for anti-smoking campaigns could help to accelerate this process, and we may yet see the beginning of the end to the tobacco epidemic, when potential new recruits start to lose interest in cigarettes. Actmowledgement The support of the Imperial Cancer Research.Fund is gratefully acknowledged. References COHEN, S. (1986) Contrasting the Hassles Scale and the Perceived Stress Scale: Who's really measuring appraised stress?, American Psychologist, 41, pp. 716-718. FAGERSTROM, K.-O. & SCHNEIDER, N. 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