The aim of this study was to analyze the influence of personality patterns assessed with the MCMI-III and nicotine dependence on smoking status (at the end of the treatment and at 12 months follow-up) in a sample of 288 men and women smokers receiving cognitive-behavioral treatment for smoking cessation. The results indicated differences between men and women in the personality patterns analyzed in the present study, and that nicotine dependence plays a relevant role in treatment outcomes.
When assessing the personality patterns of smokers seeking smoking cessation treatment, we found that women score significantly higher in the Histrionic and Compulsive patterns, whilst in men the Narcissistic pattern is the most prevalent. This result is in line with those of other studies, such as that of Berlin et al. , who concluded that there are different reasons for smoking in men and in women: women smoked more for tension reduction/relaxation, stimulation and social reasons than men. In a similar line, Millon  argues that the Compulsive pattern is characterized by continuous tension, and the Histrionic pattern by a need for continual social reinforcement.
We did find differences regarding to which patterns predict such dependence. In men, nicotine dependence was predicted by a high score in the Antisocial pattern and a low score in the Narcissistic pattern, and in women it was predicted by a high score in the Schizoid personality pattern. Nieva et al.  had already found that low Sociability predicts nicotine dependence in men, but in the women’s group no personality scale emerged as a significant predictor of nicotine dependence.
On the other hand, we did find differences by gender in relation to the patterns most strongly related to smoking abstinence at the end of the treatment. Men with a high score in the Compulsive pattern were likely to stop smoking, but high scores in the Depressive, Antisocial, Sadistic, Negativistic, Masochistic, Schizotypal and Borderline personality patterns were associated with lower percentages of abstinence at the end of the treatment. The Antisocial and Borderline patterns have in common the Impulsiveness trait, which according to Nieva et al.  is related to smoking relapse in men. The only personality pattern associated with treatment outcomes in women was Schizoid. Women with a high score on this personality pattern were less likely to stop smoking. According to the results obtained in the present study, this pattern is related to a higher nicotine dependence in women who seek treatment and nicotine dependence is related to higher difficulties to quit smoking .
Long-term outcomes were also different according to personality patterns. In men, a high score in the Compulsive pattern was related to continuous abstinence at 12-months follow-up, while in women no pattern was significant. Previous studies carried out from Millon’s personality model , without taking into account gender, also found good results among smokers with this personality pattern. A plausible explanation is that people with this pattern are highly perfectionist and inflexible in their decisions, an example of which would be the decision to attend a specific treatment smoking cessation program. If we bear in mind that the criterion in the present study for classifying a participant as abstinent at 12-months follow-up was not having smoked a cigarette, not even a puff, since the end of the treatment, it would not be surprising to find that participants with this personality pattern are those with the highest probability of remaining abstinent in the long term. In the same line, another reflection of the high level of control in people with this pattern are the results of studies carried out with psychoactive substance users, in which this personality pattern shows low prevalence [38, 39].
Concerning the regression analysis, nicotine dependence is the determining variable for smoking status in both short and long term, regardless of gender. In men only, the Masochistic pattern partly explains poor outcomes at the end of the treatment. Nicotine dependence is considered the key variable for explaining the results of smoking cessation interventions according to previous studies [19, 40, 41], which have concluded that people with higher nicotine dependence have more problems to maintain long term abstinence.
However, the results also indicated that certain personality patterns predict nicotine dependence and that there were significant differences according to gender. On the one hand, the Schizoid pattern has been linked to smoking at the end of the treatment in women, and on the other hand, higher scores in this pattern was associated with higher nicotine dependence. The Antisocial personality pattern has been linked to lower percentages of abstinence, and has been a pattern that contributes to explain the variance of FTND in men. Thus, we know that certain personality patterns, which differ according to gender (e.g., Schizoid in women), are related to greater dependence, which in turn predicts poorer results both at the end of the treatment and at the 12-month follow-up.
Some limitations in this study should be noted. First, the sample is not representative of the total population of smokers, since it includes only those who sought smoking cessation treatment, and we know that this type of population has different characteristics from those of smokers from the general population. Therefore, we could expect that the patterns and the differences found by gender could vary in the profile of smokers who stop smoking without following a specific treatment, so that our results could be extrapolated only to similar clinical samples. As Hughes et al.  and Le Strat et al.  point out, the results obtained in studies with smokers who seek treatment are not generalizable to smokers of the general population due to the particular characteristics of persons who seek treatment. Thus, it would be necessary to conduct studies out of clinical samples to know how results would be. Secondly, the instrument used for the assessment of personality patterns, the MCMI-III, is based on a specific theoretical perspective. Theodore Millon’s personality model has large numbers of both advocates and detractors, but despite its critics it is one of the most widely used with clinical population in the study of personality [44, 45]. However, to our knowledge, this is the first study which examines the relationship between personality according to Millon’s model and smoking cessation outcomes in a large clinical sample, taking into account the contribution of gender to this relationship.