Michael S. Dunbar

Smoker reactivity to cues: effects on craving and on smoking behavior.

We assessed craving and smoking in response to smoking-relevant cues. Two hundred seven daily smokers viewed images related to 1 of 6 cue sets (cigarettes, positive and negative affect, alcohol, smoking prohibitions, and neutral cues) in separate sessions. Compared with neutral cues, cigarette cues significantly increased craving, and positive affect cues significantly decreased craving. When subjects were then allowed to smoke during continuing cue exposure, cues did not affect the likelihood of smoking or the amount smoked (number of cigarettes, number of puffs, puff time, or increased carbon monoxide). However, craving intensity predicted likelihood of smoking, latency to smoke, and amount smoked, with craving increases after cue exposure making significant independent contributions. Some craving effects were curvilinear, suggesting that they are subject to thresholds and might not be observed under some circumstances.

Smoking motives of daily and non-daily smokers: A profile analysis

BACKGROUND Non-daily or intermittent smoking is becoming common, but little is known about smoking patterns of intermittent smokers (ITS). This study assesses differences in the profile of smoking motives of non-daily, ITS and daily smokers (DS). METHODS Participants were 218 DS and 252 ITS (152 converted ITS [CITS], who previously smoked daily, and 80 native ITS [NITS] who did not), not currently quitting, recruited by advertisement. ITS were defined as smoking 4-27 days per month; DS as smoking daily, 5-30 cigarettes per day. Participants completed the Wisconsin Inventory of Smoking Dependence Motives (WISDM), yielding scores for 13 different motives. The within-profile standard deviation expressed profile scatter (differentiation among motives), and profile shape was assessed on scores standardized for within-profile mean and standard deviation. RESULTS There was no difference between ITS and DS on profile scatter. ITS and DS differed in the shape of the standardized score profile, with DS scoring higher on Tolerance, Craving, Automaticity, Loss of Control and Behavioral Choice motives, and ITS scoring higher on Cue Exposure, Weight Control, and Positive Reinforcement motives. CITS did not differ from NITS in profile scatter or profile shape. CONCLUSION ITS differ from DS in the relative importance of motives, with ITS emphasizing motives associated with acute, situational smoking, and DS emphasizing dependence-related motives. Among ITS, history of daily smoking did not influence the profile of motives.

Do smokers crave cigarettes in some smoking situations more than others? Situational correlates of craving when smoking.

INTRODUCTION Smokers tend to smoke when experiencing craving, but even within smoking occasions, craving may vary. We examine variations in craving when people were smoking in various real-world situations. METHODS Using Ecological Momentary Assessment, 394 smokers recorded smoking, craving, and smoking context in real time on electronic diaries over 2 weeks of ad libitum smoking. Assessments occurred immediately prior to smoking. Mixed modeling was used to analyze associations between craving and situational variables. RESULTS Craving varied across smoking situations, but the differences were small (<1 on a 0-10 scale). Specifically, craving was higher in smoking situations where smoking was restricted, likely because high craving leads smokers to violate restrictions. Controlling for restrictions, craving was higher when cigarettes were smoked while eating or drinking, were with other people (vs. alone), were in a group of people (vs. other people simply in view), during work (vs. leisure), and during activity (vs. inactivity). In addition, craving was higher for cigarettes smoked early in the day. No differences in craving were observed in relation to drinking alcohol or caffeine (vs. doing anything else), being at work (vs. home), being at a bar or restaurant (vs. all other locations), interacting with others (vs. not interacting), or other people smoking (vs. no others smoking). DISCUSSION Even though most craving reports prior to smoking were high, and situations were thus expected to have little influence on craving, results suggest that some cigarettes are craved more than others across different smoking situations, but differences are small.

The 677 C-T methylenetetrahydrofolate reductase mutation does not predict increased maternal homocysteine during pregnancy.

OBJECTIVE To test the hypothesis that, regardless of the presence of the 677 C-T methylenetetrahydrofolate reductase (MTHFR) mutation, maternal homocysteine concentrations will not be significantly different in women who are taking prenatal vitamins containing folic acid, and to test this relationship in preeclampsia because homocysteine concentrations are higher in preeclamptic pregnancies. METHODS Fifty-seven pregnant white women (control and preeclamptic) with and without the 677 C-T MTHFR mutation were studied. Total plasma homocysteine and plasma folic acid were analyzed. RESULTS Homocysteine concentrations were not different by MTHFR genotype (wild type 677 CC 8.7 ± 5.6 μM versus mutant 677 TT 9.0 ±5.7 μM, P = .84) in preeclamptic or normal pregnancies. However, mean homocysteine concentrations were significantly increased in preeclamptic pregnancies compared with those in normal pregnancies (10.6 ± 7.3 μM versus 7.2 ± 3.0 μM, P < .03) as previously reported. CONCLUSION The 677 C-T MTHFR polymorphism does not significantly affect maternal homocysteine concentrations in most women taking prenatal vitamins including women with preeclampsia. The increase in plasma folic acid likely affects maternal homocysteine more than the MTHFR genotype. If homocysteine is considered a thrombophilia risk factor, the concentration of the amino acid and not a particular genotype should be determined.

Cue reactivity in non-daily smokers: Effects on craving and on smoking behavior

RationaleNon-daily, or intermittent smokers (ITS), are increasingly prevalent. Their smoking may be more situational than that of daily smokers (DS), and thus is hypothesized to be more influenced by cues.ObjectivesTo assess ITS’ response to cues, and compare it to that of DS.MethodsSamples of 239 ITS and 207 DS (previously reported in Shiffman et al. 2012a) were studied in 2,586 laboratory cue-reactivity sessions. Craving (Questionnaire of Smoking Urges) and smoking (probability, latency, puff parameters, and carbon monoxide increases) in response to cues was assessed following exposure to neutral cues and cues related to smoking, alcohol, negative affect, positive affect, and smoking prohibitions. Mixed effects models, generalized estimating equations and random-effects survival analyses were used to assess response to cues and differences between DS and ITS.ResultsITS’ craving increased following exposure to smoking and alcohol cues and decreased following positive affect cues, but cues had little effect on smoking behaviors. Cue reactivity was similar in ITS and DS. Among ITS, craving intensity predicted smoking probability, latency, and intensity, and the effects on latency were stronger among ITS than DS.ConclusionsContrary to hypotheses, ITS were not more responsive to laboratory cues than DS. Results show that ITS do experience craving and craving increases that are then associated with smoking.

Smoking During the Night: Prevalence and Smoker Characteristics

We report on the smoking patterns and characteristics of individuals who smoke at night. We also explore the relationship between night smoking, nicotine dependence, and cessation outcomes. Participants (N = 691) were heavy smokers enrolled in cessation research clinics. Data were from three studies. Using ecological momentary assessment, participants monitored their smoking (ad libitum, day and night) on electronic diaries (EDs) during a 2-week baseline period and for 4 weeks following a target quit day. A total of 41% of smokers recorded at least one episode of night smoking. Within this group, night smoking occurred on 26% of nights, averaging two episodes per night. ED data correlated with a single self-report item assessing the frequency of night smoking. Night smoking was associated with greater nicotine dependence and daily caffeine consumption. It also predicted risk for lapsing beyond traditional measures of nicotine dependence. Night smoking is common, is associated with nicotine dependence, and it represents additional risk for cessation failure. People who smoke at night may need nicotine replacement therapy overnight. Future research should determine whether treatments that improve sleep quality also improve cessation outcomes in night smokers.

Stimulus control in intermittent and daily smokers

Many adult smokers are intermittent smokers (ITS) who do not smoke daily. Prior analyses have suggested that, compared with daily smokers (DS), ITS smoking was, on average, more linked to particular situations, such as alcohol consumption. However, such particular associations assessed in common across subjects may underestimate stimulus control over smoking, which may vary across persons, due to different conditioning histories. We quantify such idiographic stimulus control using separate multivariable logistic regressions for each subject to estimate how well the subjects smoking could be predicted from a panel of situational characteristics, without requiring that other subjects respond to the same stimuli. Subjects were 212 ITS (smoking 4-27 days/month) and 194 DS (5-30 cigarettes daily). Using ecological momentary assessment, subjects monitored situational antecedents of smoking for 3 weeks, recording each cigarette in an electronic diary. Situational characteristics were assessed in a random subset of smoking occasions (n = 21,539), and contrasted with assessments of nonsmoking occasions (n = 26,930) obtained by beeping subjects at random. ITS showed significantly stronger stimulus control than DS across all context domains: mood, location, activity, social setting, consumption, smoking context, and time of day. Mood and smoking context showed the strongest influence on ITS smoking; food and alcohol consumption had the least influence. ITS smoking was under very strong stimulus control; significantly more so than DS, but DS smoking also showed considerable stimulus control. Stimulus control may be an important influence on maintaining smoking and making quitting difficult for all smokers, but especially among ITS.

Craving in intermittent and daily smokers during ad libitum smoking.

INTRODUCTION This study aimed to assess average and peak craving intensity among nondaily intermittent smokers (ITS) in smoking episodes and when not smoking compared to that of daily smokers (DS). METHODS Two hundred and twelve ITS and 194 DS monitored their smoking and craving for 3 weeks using Ecological Momentary Assessment methods. Craving was assessed (0-100 scale) when subjects lit a cigarette and at random times when not smoking; 48,469 observations were analyzed using generalized estimating equations. RESULTS ITS experienced craving, including intense craving; their 95th percentile intensity averaged 77.7 ± 22.5 out of 100 (higher among DS: 89.1 ± 14.5). ITS reported lower craving than DS, both when smoking and when not smoking. In both groups, craving was less intense when not smoking (DS: 71.1 ± 20.7 vs. 59.83 ± 21.97; ITS: 59.91 ± 23.03 vs. 26.63 ± 19.87), but the difference was significantly greater among ITS. Among ITS, the probability of smoking rose continuously as craving increased over the full range of the scale. In contrast, among DS the probability of smoking rose until the midpoint of the scale, after which the relationship flattened. Findings were mostly similar for ITS with and without a history of past daily smoking. CONCLUSIONS ITS do experience craving, including intense craving. The relationship between craving and smoking is stronger among ITS because DS experience moderate craving even between cigarettes. In contrast, ITS appear to experience craving in limited situations associated with smoking, suggesting that their craving and smoking may be driven by transient cues rather than endogenous needs.

Maternal plasma homocysteine concentrations are not increased in twin pregnancies.

Objective(s). We tested the hypothesis that twin pregnancies would lead to increased maternal plasma homocysteine. We further hypothesized that twin pregnancies complicated by preeclampsia would have increased plasma homocysteine compared to twin pregnancies without preeclampsia and normal singleton pregnancies. Methods. Plasma was collected at delivery from 127 nulliparous subjects: 57 women with normal singleton pregnancies, 39 women with singleton and preeclampsia, 17 women with uncomplicated twin pregnancies, and 14 women with twins and preeclampsia. Subjects were group matched for prepregnancy body mass index (BMI) and race. Plasma homocysteine was analyzed by high pressure liquid chromatography (HPLC) with fluorescence detection, and plasma folic acid was measured by radio immunoassay (RIA). Results. The mean plasma concentration of homocysteine was significantly increased in all women with preeclampsia (7.4 ± 2.9 µM) compared to all normal pregnant women (5.9 ± 2.1 µM, p = 0.002). However, homocysteine was not significantly increased in all women with twins (6.7 ± 2.1 µM) compared to all women with singleton pregnancies (6.5 ± 2.7 µM, p = 0.61). In addition, women with twins and preeclampsia did not have increased homocysteine (6.8 ± 2.1 µM) compared to women with twins and normal pregnancy (6.7 ± 2.1 µM, p = 0.72). As expected, because ofextra supplementation, plasma folic acid was significantly increased in women with twins (27.9 ± 11.6 ng/mL) compared to women with singleton pregnancies (20.8 ± 8.5 ng/mL, p = 0.0003). However, folic acid was not different between preeclamptics and controls (23.5 ± 10.8 vs. 21.9 ± 9.2 ng/mL respectively, p = 0.36). Lastly, there was a significant inverse correlation between homocysteine and folic acid among all the subjects (r2 = − 0.053, p< 0.01), and this correlation persisted in the women with singleton pregnancies (r2 = − 0.078, p< 0.01), but was lost in the twins (r2 = − 0.073, p = 0.14). Conclusions. With contemporary management including increased folic acid supplementation, plasma homocysteine is not increased in twin pregnancies with or without preeclampsia.