Tobacco abuse is the main avoidable cause of death and disability in the world that is unrelated to others. The World Health Organization (WHO) estimates that 4 million persons died of tobacco-related disorders in 2002 1. In Spain, the latest available data from the National Health Survey (Encuesta Nacional de Salud) in 2003 2 describe a prevalence of tobacco consumption of 31%, with a decrease in consumption by males, and a small but significant increase in consumption by females, mainly in adolescents and young women. For these reasons tobacco use is considered a public health problem and its treatment constitutes a challenge for health services.

At present, tobacco dependence management is carried out in a collaborative way in primary care and specialised settings by means of treatments that range from minimal to intensive intervention 3. In the latter, a multi-component cessation intervention is applied by health professional specialised in tobacco dependence management 45. The multi-component intervention includes first-line pharmacological treatments for tobacco such as Nicotine Substitution Therapy (NST) or bupropion, and psychological treatments. This intervention obtains a remission rate of 30–40% at 1-year follow-up 56. As psychological therapy, cognitive-behavioural interventions, which can be administered on a group or individual basis, are used with follow-up sessions during the first year of abstinence. NST is administered by transdermal patches as basal treatment 789, added to nicotine lozenges 10 or nicotine chewing gums 11 that are self-administered occasionally depending on abstinence symptoms. Bupropion is a noradrenergic and dopaminergic antidepressant used for tobacco dependence because it acts on nicotinic receptors. It is twice as effective as a placebo for this treatment 12. However, in psychiatric patients it should be used with caution owing to potential interactions with CYP2D6, an enzyme involved in the metabolisation of many psychiatric drugs 13.

Topiramate seems to be a new and promising pharmacological treatment for tobacco. A new antiepileptic drug, it was originally designed as an oral hypoglycaemic, and was subsequently approved as an anticonvulsant. It has increasingly been used in the treatment of numerous psychiatric conditions (binge eating disorders, bulimia nervosa, and alcohol dependence) and it has also been associated with weight loss, potentially relevant in reversing weight gain induced by psychotropic medications 14. Topiramate has demonstrated its efficacy for the treatment of alcohol dependence in randomised controlled trials 15. There are also some preliminary reports of its effectiveness for the treatment of tobacco dependence, despite these reports being substudies of other trials on alcohol dependence 16, uncontrolled studies with small samples 17 or short-term studies 18.

Recently, a group of smokers have been described as "special populations". These are groups with certain characteristics that require the need for more intensive treatments to attain tobacco cessation, owing to limitations in the use of pharmacological treatments (pregnancy) or because the cessation must be more immediate (patients with heart disorders or emphysema) 4. One of these special populations is psychiatric patients in whom prevalence of tobacco dependence is higher than in the general population (52% vs. 31%) and effectiveness of cessation programmes are less effective 19. In persons who smoke, there is a direct relationship between severity of psychiatric symptoms and tobacco dependence 20. Specifically, patients with depression show more likelihood to become heavy smokers, to have more difficulties in stopping smoking, and to suffer from more abstinence symptoms than general population 21. At present, there are not enough research studies on the effectiveness of topiramate for tobacco cessation and, specifically, in psychiatric populations such as patients with depression.

Effectiveness of multi-component programmes with standard pharmacological treatments (NST) for tobacco cessation in the general population is still unsatisfactory, with cessation rates at 1-year follow-up ranging from 30–40% 56. These rates are even less successful in special populations such as psychiatric patients 19. For these reasons, it seems necessary to develop new and more effective pharmacological treatments. One of the most promising treatments is topiramate because it has demonstrated effectiveness on tobacco cessation in preliminary studies 161718, and it is useful in many psychiatric conditions 14.

The strength of the study is that, to our knowledge, this is the first randomised, controlled trial of topiramate for tobacco cessation, with the standard treatment (NST) as comparator. The psychological intervention of the multi-component programme is the usual group cognitive-behavioural therapy used in these programmes 19. In addition, the modulator role of some important variables (such as anxiety, impulsivity, state of change, self-efficacy) in patients with depression has also been assessed.

A number of potential limitations may be difficulties in recruitment, due to lack of motivation for tobacco cessation in psychiatric patients, and the low cessation rate in this population making it difficult to interpret the results. The concept of states of change has also been criticised, so its utility may be doubtful.

The authors declare that they have no competing interests.

JGC is the principal researcher and developed the original idea for the study. The study design was further developed by MA, NS and RM. NS, AM, AC and BS participated in the design and planning of the intervention that is evaluated here. EA developed the statistical methods. All authors have read and corrected draft versions and approved the final version.