The WHO identifies tobacco smoking as a major preventable risk factor for disease, disability, and death 1. For the past few decades, researchers have focused on smoking behavior and addiction predictors, and on potential interventions to quit smoking 2,3. Although most smokers would like to quit, few succeed even with behavioral counseling and pharmacological intervention 4,5.
To better understand smoking behavior and addiction, researchers have focused on individual differences in personality and psychological traits. Indeed, they reported associations between smoking and other substance use, antisocial personality disorders, 6,7 and depressive disorders 8,9. Among smokers, major depression has been linked to their inability to stop smoking and to their high relapsing rate when they attempted to quit 10–12. Tobacco dependence has been related to higher lifetime rates of major depression 13 and to neuroticism 14. The latter is a broadly defined domain of personality that encompasses various aspects of negative affect and emotionality such as depression, anxiety, hostility, impulsiveness, and vulnerability to stress 15,16. Previous studies have shown that individuals who score high on neuroticism scales are more likely to smoke, be nicotine dependent, and less likely to stop smoking 13,15,17.
Although relationships of both psychiatric history and personality traits with smoking and smoking dependence have been demonstrated, the interrelationships among these variables have not been fully defined. Theory and empirical research suggest that there is a substantial overlap between psychiatric disorders and personality traits 18, but few studies have assessed simultaneously personality and psychopathology and their distinct and overlapping associations with smoking and addiction. Furthermore, prior research has focused narrowly on the Fagerström Test for Nicotine Dependence (FTND) 19; however, very few have addressed associations between smoking dependence motives and individual differences in behavioral and affective functioning. For example, individuals who score high on the neuroticism scale and those with depressive symptoms are more likely to report smoking to alleviate negative affect 20.
In Egypt, we are unaware of research that addresses the association of personality traits, psychiatric disorders with smoking behavior in population-based settings. In addition, the interaction of these traits with smoking behavior might be different from what have been reported by other investigators in developed countries, because of the differences in smoking behavior that is heavily influenced by cultural and environmental factors 21. In the present study, we investigated the relationships between personality traits (neuroticism) and depression symptoms and smoking dependence and motives among healthy adult men in Egypt. The overall goal is to improve the interventions for smoking cessation through personalized treatment.
Subjects and methods
The Institutional Review Boards of University of Maryland (Baltimore), Georgetown University, and the Ministry of Health and Population in Egypt approved the study protocol.
From 2003 to 2004, a household survey on smoking was conducted in several villages in rural northern Egypt using a systematic random sampling technique. Among several thousand participants aged 18 years or above, half were men (49.2%) and current smoking was reported by 37.6% of them, whereas current smoking prevalence was only 0.1% among women 21. For the present study, we approached adult men aged 18 years or above from five of those rural villages in Northern Egypt Qalyubia Governorate, a governorate that was chosen because it is highly accessible to the Center for Field and Applied Research (CFAR) of the Ministry of Health and Population. We used the same random sampling technique that was used earlier 21 to select three groups as follows: (a) current cigarette smokers were those who smoked at least 10 cigarettes daily, for a minimum of 5 years, and did not use any other tobacco products; (b) Former smokers were those who smoked in the past but were able to successfully quit smoking and had not smoked for the past year; and (c) never smokers were those who never tried cigarettes or other tobacco products in their lifetime.
Trained interviewers from the CFAR approached the participants and explained the purpose of the study. For those who agreed to participate and signed informed consent, the interviewers administered the following standardized questionnaires: (a) one which elicited information about sociodemographic characteristics such as age, marital status, occupation, smoking status and history (age at initiation, daily number of cigarettes smoked, and quitting attempts), and family and friends smoking behavior; (b) the FTND that assesses dependence severity 19; (c) the Wisconsin Inventory of Smoking Dependence Motives (WISDM) 22, a 68-item measure that assesses 13 smoking dependence motives [affiliative attachment to smoking, automaticity of smoking, loss of control over smoking, behavior choice–melioration (smoking despite constraints), cognitive enhancement, craving, cue exposure (strength of association between nonsocial smoking cues and craving), smoking for negative reinforcement, smoking for positive reinforcement, social/environmental goads (stimuli) that encourage smoking, taste/sensory properties of smoking, tolerance, and smoking for weight control] 23; (d) a 10-item version of the Center for Epidemiologic Studies Depression (CES-D) scale where a score of 10 or greater indicates the presence of depressive symptoms 24; and (e) the Eysenck Personality Inventory (EPI) neuroticism subscale to assess heightened anxiety and reactivity to stress 25. The neuroticism subscale consists of nine questions that are part of the original Eysenck personality questionnaire 26, an instrument that has been extensively used to assess personality trait and shown to correlate with clinical measures of anxiety and depression 27.
FTND scores were categorized as mild (scores 0–4), moderate (5–7), and severe addiction (score≥7). The 13 smoking motives based on the WISDM were created as described by Shenassa et al.23 On the basis of the median value (score=5), the neuroticism variable was dichotomized as low (≤5) and high (>5). For CES-D scale, a score of 10 or greater indicated the presence of depressive symptoms.
We performed a descriptive analysis (mean±SD for numerical variables and percentages for categorical variables) to compare the characteristics of the three different groups: current, former, and never smokers. The χ2-test and analysis of variance were used to compare categorical and continuous variables, respectively. We used the Mann–Whitney U and the Kruskal–Wallis tests to compare the three groups with respect to their depression and neuroticism scores.
Logistic regression models were used to examine the associations between neuroticism and depression (as predictor variables) and smoking status (ever vs. never, with ever including current and former smokers) as the dependent variable, after adjustment for potential covariates such as age, marital status, education, and occupation. Odds ratio (OR) and 95% confidence interval was reported as estimates of the association. All the statistical analyses were performed using the SPSS version 16.0 software (IBM, Chicago, USA) program package and SAS version 9.2 software (SAS Institute, Cary, North Carolina, USA).
Characteristics of the study participants
We enrolled 201, 120, and 278 men who were never, former, and current smokers, respectively. The characteristics of the three different groups are shown in Table 1. The mean age was significantly higher among current and former smokers as compared with never smokers (40, 44, and 30 years, respectively; P<0.001). A significantly higher proportion of never smokers was observed among participants with more than secondary education as compared with those with lesser education (P<0.001). Having parent or friends who smoke was reported more frequently by current smokers than by nonsmokers (73.4 vs. 60.7%, and 52.6 vs. 18.9%, respectively) (Table 1). When current and former smokers were asked about the reasons they started smoking, the vast majority reported peer emulation (79 and 85%, respectively) and peer pressure (68 and 69%); curiosity was the next most frequently reported reason (56 and 62%).
Associations between depression, neuroticism, and smoking behavior
As shown in Table 1, the lowest mean scores for CES-D and for EPI subscale were observed among never smokers, and they were statistically significantly different from the scores of current smokers (P=0.02 and 0.006, respectively). Among current smokers, the mean CES-D scores were significantly higher among those who smoked more than 20 cigarettes daily as compared with those who smoked fewer cigarettes (P=0.02), and they were significantly lower among those who did not attempt to quit as compared with those who did (P=0.05). Neuroticism was borderline significantly associated with younger age at initiation (P=0.06) (Table 2).
Among current smokers with different levels of nicotine dependence severity, neither CES-D or EPI scores were significantly different, and although both of these scores tended to increase with the severity of FTND, the trend was not statistically significant (Table 2). Most of the smoking motives scores, as determined by the WISDM instrument, were significantly higher among neurotic patients (EPI score>5) and among those with depressive symptoms (CES-D≥10) as compared with those with EPI score of 5 or less and CES-D score of 10 or less, respectively (Table 3). Interestingly enough, affiliation attachment, automaticity, behavioral choice, and positive reinforcement, all of which are indicative of anxiety, were significantly associated with both neuroticism and depression.
Logistic regression analysis was conducted with smoking status as the outcome variable and neuroticism or depression as predictors. We fit three different models that contrasted never smokers to: (a) former and current smokers combined; (b) only former smokers; and (c) only current smokers. Having high neuroticism or depressive symptoms was associated with the risk of being ever smoker, after adjustment for age, marital status, education, and occupation; the association was statistically significant with the former and borderline significant with the latter [ORs (95% confidence interval) were 1.70 (1.17–2.48) and 1.38 (0.96–1.99), respectively]. When we included both neuroticism and depression with the covariates and fit separate models for former and current smokers, the association of high neuroticism with current smokers remained significant and the association of depression with former smokers became significant (Table 4).
We fit a multivariable model with both CES-D and EPI scores and an interaction term of these two variables as well as the covariates; the interaction between depressive symptoms and neuroticism was not significant. We also fit separate multivariable models that included only those who reported (a) both depression and neuroticism, (b) neuroticism but no depression, (c) depression but no neuroticism, and (d) neither depression nor neuroticism. Interestingly enough, having both high neuroticism and depressive symptoms was associated with elevated risks for being a former smoker [2.56 (1.34–4.88)] and to a much lesser extent a current smoker [1.82 (1.10–3.03)] (Table 4).
We found that current smokers had greater scores for both depressive symptoms and neuroticism as compared with never smokers, and there was a significant association between CES-D scores and the number of cigarettes smoked per day. The risk for being an ever smoker was significantly associated with neuroticism and to a lesser extent with depression, and the greatest smoking risk was observed when both were present. In addition, most of the smoking motives scores, as determined by the WISDM, were significantly higher among neurotic patients (EPI score>5) and those with depressive symptoms (CES-D≥10) as compared with those with lower scores for either personality trait or psychopathology.
These findings are consistent with and extend prior research that documented the association between depression and smoking. A recent review by Mendelsohn 28 showed the cumulative evidence for smokers being more likely than nonsmokers to have a history of major depression and for an association between depression and inability to stop smoking; however, few studies showed no association 29,30. In our study, we found that the association of having depressive symptoms with being a former smoker to be greater than that with being a current smoker. This finding indicates that, among Egyptian men, having depressive symptoms is not an impediment to smoking cessation, especially because these former smokers have been abstinent for 1 year or longer. In addition, it is consistent with the view point that smoking cessation might lead to relapse among individuals who had history of major depression, as previously reported 31. Another explanation for the strong association between depressive symptoms and smoking cessation for at least 1 year is that smoking was used by Egyptian men as self-medication, a concept that was previously suggested by other investigators 32.
Similarly, the relationship between neuroticism and smoking behavior has been widely supported 6,15,16. We, similar to others, 33 found that high neuroticism was significantly associated with smoking after adjustment for covariates and for depression, and in the absence of depressive symptoms, the OR remained elevated, albeit not statistically significant (Table 4). Having both depression and neuroticism was definitely associated with increased odds of ever smoking, and more so of being former smoker. A recent meta-analysis by Munafo et al.7 demonstrated modest but significant associations between smoking status and neuroticism as measured using instruments developed by Eysenck. Tate et al.32 hypothesized that neurotic individuals would smoke to reduce tension and anxiety, a hypothesis that was supported by longitudinal data showing neuroticism (high EPI scores) as a risk factor for smoking initiation 34. Although the design of our study is cross-sectional and thus does not allow us to determine whether neuroticism and depression among smokers are causes or effects of smoking, our finding that neuroticism, which is a personality trait, was associated with early age at smoking initiation (Table 2) and with motives, such as affiliation attachment, automaticity, and positive reinforcement (Table 3), reinforces Khantzian’s hypothesis 34.
We did not observe a significant association between neuroticism or depression and tobacco dependence using FTND; however, we found a significant association between neuroticism, depression, and a variety of smoking motives using the WISDM – a 68-item measure that assesses 13 smoking dependence motives. WISDM has shown adequate psychometric properties 23. Four of the WISDM subscales (automaticity, craving, loss of control, and tolerance) are considered core components of tobacco dependence, whereas the remaining scales are considered secondary aspects of dependence that do not have to be present among those with severe smoking dependence 35. We found that depressed patients (with CES-D≥10) had significantly higher scores for automaticity, craving, and loss of control, but not for tolerance (Table 3). It is possible that, in selecting current smokers as those who smoked at least 10 cigarettes per day and for the past 5 years, we excluded those who smoked fewer than 10 cigarettes daily and those who smoked more than 10 cigarettes but for less than 5 years; all of whom could represent smokers with low nicotine dependence scores.
The present study has some limitations related to the cross-sectional design that prohibits the ascertainment of temporal relationship between psychopathology and smoking behavior. In addition, we enrolled only adult men from rural Qalyubia and selected current smokers as those who smoked at least 10 cigarettes daily for the past 5 years and no other form of tobacco. Therefore, we cannot generalize our results to other ages, urban dwellers, women, and other types of smokers. Nonetheless, we were able to compare ever smokers (former and current) with never smokers (Table 4). Finally, smoking status was assessed by self-report and not validated biochemically; however, the data were collected as part of a larger survey under conditions of anonymity, and we have no particular reason to doubt the veracity of these self-reports.
Our study findings suggest that depression and neuroticism are associated with smoking behavior and motives, and thus they add to the growing evidence for an association between cigarette smoking and personality traits, and hence for smokers being a heterogeneous group for whom treatment modalities should be diverse. A combination of public policy and treatment strategies tailored to the needs of individual smokers may be required to effectively reduce the prevalence of cigarette smoking.
This study was supported by grant # B1011-002-005 from the US and Egypt Science & Technology Joint Fund.
Conflicts of interest
There are no conflicts of interest.
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