واکنش پذیری روانی فیزیولوژیایی دود سیگار در افراد سیگاری و غیر سیگاری

Abstract Environmental tobacco smoke (ETS) is an air pollutant with a relevant impact on public health. In addition, ETS is a significant stimulus that may elicit different responses depending on previous experience and current status regarding smoking. Exposure to cigarette cues has been shown to be a reliable method for inducing subjective and physiological responses. However, the role of ETS as a stimulus has not received, to date, enough attention in the research literature. This study aimed to analyse both the autonomic and subjective responses of smokers and non-smokers to exposure to ETS. To that end, 41 non-smokers and 57 smokers were exposed to ETS, in a controlled laboratory setting. We measured the subjective perception of smoke, unpleasantness, heart rate and skin conductance to compare the reactions of smokers and non-smokers to ETS. Additionally, subjective tobacco craving after exposure was assessed for current smokers. We found different psychophysiological responses to ETS exposure for smokers and non-smokers. Smokers showed a generalised increase in autonomic activity, significantly greater than that of non-smokers. In addition, heart rate increase during exposure to ETS was positively correlated with subjective craving. Our data suggested that ETS was an important stimulus and acted as a relevant cue for smokers; it induced both psychophysiological reactions and subjective craving. Hence, this kind of stimulus within the cue-reactivity research paradigm may be useful for studying the effect of ETS on smokers' reactions, craving, quitting attempts, or relapse probabilities.

. Introduction Exposure to cigarette cues has been shown to be a reliable method for eliciting subjective and physiological responses among smokers (Carter et al., 2009, Field et al., 2004, Lee et al., 2005 and Miranda et al., 2008). The typical reaction includes an increase in subjective craving and, physiologically, an alteration in autonomic responses. For example, exposure to smoking-related cues appeared to increase an electrodermal response or skin temperature (Carter and Tiffany, 1999, Carter et al., 2006, Doran et al., 2008, Field et al., 2004, Miranda et al., 2008 and Tong et al., 2007). This exposure also appeared to affect cardiovascular reactivity (e.g., heart rate or blood pressure); however, these results are inconsistent (Tong et al., 2007). Both subjective and physiological responses seem to be affected by several other variables, including gender, nicotine deprivation, presence of environmental stressors, induction of a negative affect, impulsivity, alcohol intoxication, or smoking availability (Bailey et al., 2009, Doran et al., 2008, Perkins et al., 2001 and Tong et al., 2007). Cue reactivity studies are typically conducted in a laboratory setting with a variety of stimuli. Most stimuli are 2-dimensional images (Attwood et al., 2008, Carter et al., 2009, Lochbuehler et al., 2010, Mogg et al., 2005, Tong et al., 2007 and Upadhyaya et al., 2004) but some groups have used in vivo cue exposure, where the deprived subjects are shown objects like cigarettes, lighters (Bailey et al., 2009, Doran et al., 2008, Miranda et al., 2008, Naqvi and Bechara, 2006, Payne et al., 2006, Tidey et al., 2005 and Upadhyaya et al., 2006), or even virtual reality scenarios (Lee et al., 2005, Paris et al., 2011 and Traylor et al., 2011). Olfactory perception has specific value as a cue for smoking that is not applicable to drugs like cocaine or heroin. The aroma of tobacco differs from that of alcohol because it can be perceived at a relatively long distance. The aromas of cigarettes and smoke have an important evocative value for smokers because they trigger the urge to smoke (Grüsser, Heinz, & Flor, 2000). Nevertheless, olfactory stimuli have not received enough attention in the cue-reactivity literature on smoking. For instance, Grüsser et al. (2000) specifically analysed the effect of nicotine aroma and concluded that it increased craving in deprived smokers. However, they measured only subjective responses. Smoking-related olfactory stimuli may also be present within a more general context of in vivo exposure used in other studies. Procedures included allowing the subject to manipulate cigarettes; light a cigarette, but not touch it to the mouth; or watch someone else smoke in the same room (Carpenter et al., 2009, Collins et al., 2011, Doran et al., 2008, Miranda et al., 2008, Payne et al., 2006, Sayette and Parrott, 1999, Tidey et al., 2005, Upadhyaya et al., 2006 and Watson et al., 2010). All of these procedures could involve cigarette or smoke aroma, but as a by-product, or secondary stimulus, and in a mixture with other visual or contextual cues simultaneously. Those that recorded psychophysiological responses found increases in electrodermal activity (Carpenter et al., 2009); reports of cardiovascular response (e.g., changes in heart rate or blood pressure) have been inconsistent (Doran et al., 2008, Erblich et al., 2011, Miranda et al., 2008, Payne et al., 2006, Tidey et al., 2005 and Upadhyaya et al., 2006). Nevertheless, in all these studies, the stimulus-exposure condition was nonspecific and there was no measure of olfactory perception. Hence it is not possible to determine how the smoke aroma contributed to the measured responses, or even whether it was actually perceived. Thus, to our knowledge, no study has measured specifically both subjective and physiological responses of smokers to a tobacco-related olfactory stimulus, like ETS. It is well known that exposure to environmental tobacco smoke (ETS) is associated with increased morbidity and mortality for smokers and non-smokers. ETS appears to affect cardiovascular activity (Dietrich et al., 2007), but it also has a relevant stimulus value. ETS is associated with smoking behaviour and previous experience, and it has been suggested that sensory cues like ETS may acquire incentive value through a learned association with drug reward mediated by the central nervous system (Megerdichian, Rees, Wayne, & Connolly, 2007). Additionally, it provides a small dose of the addictive substance, which might enhance a craving for smoke. In many countries, recent regulations regarding smoking in public places have considerably reduced the exposure to ETS; however, ETS has not been completely eliminated, and it remains a controversial issue for some socio-economic sectors. On the other hand, ETS as a stimulus may have different effects on smokers (current and previous) and non-smokers; acting to increase craving and the probability of relapse for the former and as an aversive stimulus for the latter. Therefore, an analysis of the response to ETS may offer relevant information for understanding the immediate response of both, smokers and non-smokers, to ETS, the impact of ETS on attempts at quitting, and the necessity of retaining public smoking regulations. The present study is a preliminary analysis of autonomic and subjective responses elicited by ETS. We exposed subjects to tobacco smoke in a controlled laboratory setting and compared measures of heart rate (HR), skin conductance, and subjective perceptions of smokers to those of non-smokers. Additionally subjective craving after exposure was assessed for current smokers in order to test whether laboratory exposure to ETS is appropriate for eliciting craving and the utility of this procedure in studying cue-reactivity responses. Taking into account the common findings in cue-reactivity literature, we hypothesised that subjects exposed to ETS would experience an increase in autonomic responses (i.e., SCL and HR), and that such increase would be higher for smokers than for non-smokers. We also hypothesised that exposure to ETS would cause an associated increase in smokers' subjective craving.

Results 3.1. Preliminary analyses One-way ANOVAs revealed that both smokers and non-smokers perceived tobacco smoke to a similar degree [F(2,94) = 0.683; p = 0.508]. Regarding psychophysiological reactions, no group differences (smokers vs. non-smokers) on baseline levels were found for SCL [F(1,97) = 3.63; p > .05], or HR [F(1,96) = 3.28; p > .05]. Also, no significant differences were found between the sexes for SCL [F(1,114) = .35; p > .05], or for HR [F(1,112) = .74; p > .05]. Finally STAI-T scores were not different between groups [F(1,96) = 1.38; p > .05] or sexes [F(1,96) = 0.07; p > .05] either. 3.2. Autonomic response Initially, during the introductory set, SCL slightly decreased for both smokers and non-smokers. Then, when ETS penetrated the chamber and the subjects started to perceive it, SCL progressively increased for all subjects. However, that trend was much more accentuated in the smoker than the in non-smoker group (Fig. 1). A two-factor ANOVA with repeated measures as one factor revealed that SCL was significantly affected by time [F(2.719,261.02) = 33.52, p = 0.000], group [F(1,96) = 4.57, p = 0.035], and the interaction between them [F(2.719,261.02) = 5.17, p = 0.002]. Mean changes (difference scores) in skin conductance levels (microSiemens=μS) ... Fig. 1. Mean changes (difference scores) in skin conductance levels (microSiemens = μS) over time for smokers and non-smokers; ETS: Environmental tobacco smoke; Epochs were 60 s for visual stimuli and 20 s for ETS and residual ETS. Figure options The HR response showed a somewhat distinct pattern between groups. In the non-smokers group, HR remained below baseline levels during the introductory set. When ETS was perceived, HR increased to the baseline level, then slightly decreased, and remained below baseline to the end (Fig. 2). However, smokers did not show a clear initial decrease and, after perceiving ETS, HR increased and remained above baseline for the whole experimental period with some variations; the largest increase appeared during the residual smoke phase. Mean changes (difference scores) in heart rate over time for smokers and ... Fig. 2. Mean changes (difference scores) in heart rate over time for smokers and non-smokers; ETS: Environmental tobacco smoke; Epochs were 60 s for visual stimuli and 20 s for ETS and residual ETS. Figure options The mixed ANOVA with repeated measures as one factor revealed that HR was significantly affected by time [F(5.35,530.32) = 2.67, p = 0.019] and group [F(1,94) = 5.63, p = 0.020], but not significantly by the interaction [F(5.35,530.32) = 0.74, p = 0.60]. 3.3. Self-reported measures As expected, non-smokers rated the perception of ETS as more unpleasant than smokers [F(2,94) = 8.069; p = 0.001]. This score correlated positively with smoke perception for both non-smokers (r = 0.76; p < 0.001) and smokers (r = 0.48; p < 0.001). However subjective craving was negatively correlated with unpleasantness for the smokers (r = − 0 274, p = 0.045). Pearson correlation coefficients between psychophysiological responses and self-report scores were also calculated. HR correlated positively with subjective craving during the exposure to ETS (r = 0.300, p = 0.025). No other significant correlations were found between these variables.