Craving and the fight against craving
Craving – the irresistible urge to smoke – is a major feature of tobacco addiction and a factor in relapsing in the long-term. For a successful break with smoking it is essential to control craving, either with medication and/or with non-medicated solutions.
Craving: definition and most recent data
Craving is manifested by “the irrepressible desire for substance consumption” (1) O Guillin et al (2000), after the intake of a small amount of a product (drugs, alcohol, cigarettes) or without any actual consumption, years after successful treatment. It’s a subjective, motivational condition involving an impulse to search for a product and to consume it in a compulsive manner. It’s a factor in both sustaining and the seriousness of dependence, but also in relapse. Tobacco craving is associated with nicotine withdrawal symptoms but it can also appear beyond the quitting stage, a long time after having stopped smoking. One study showed that after one year of having quit, 50% of ex-smokers manifested a periodic craving and 10% a monthly craving. (2) Craving is predictive of giving up smoking in the short- or long-term. It should, therefore, be gauged both on quitting and on the follow-up period after quitting. It can be evaluated both clinically and psychometrically (QSU-brief or Tobacco Craving Questionnaire – TCQ in short form).
What circumstances encourage craving? The access to tobacco first of all, but also the priming effect (smoke inhalation which sets off craving or the consumption of other addictive substances such as caffeine), circumstances linked to an outside context (example of a smoker who has quit but who as an urge to smoke after a good meal, or when he/she is under stress), or even an internal context (the person experiences feelings usually associated with consumption of the product, such as shame, guilt or euphoria…). It has been shown that the display of visual stimuli (photos or videos linked to smoking or cigarettes) increases the desire to smoke. (3) A study carried out on people who had not smoked for one to two years showed that the factors associated with craving were feelings of depression, consuming alcohol and frequenting places associated with smoking. (4)
What is the mechanism for craving? There are different explanatory models. The chronic consumption of psychoactive substances, for instance nicotine, changes the neural circuit function indefinitely. Studies carried out using imagery show a mesocorticolimbicimplication. (5) A number of neurobiochemical mechanisms are involved in craving. (6) The likelihood of relapse comes from an interaction within subcortical structures (dopamine, GABA, Glutamate, 5-HT…) Various neurobiological models have been suggested: reward craving (dysregulation of the dopa/opioid systems), relief craving (GABA/glutamate dysregulation), obsessive craving (5-HT dysregulation).
Psychopathological aspects are also suggested, notably the theory of conditioning (conditional stimuli will induce conditioned responses copying symptoms of lack, of which craving is a psychological manifestation) and cognitive theories (internal/external balance; balance between the two systems: positive (stimuli) and negative (quitting) with them balancing each other out; coping strategies and subject control). There are numerous theories on craving that co-exist therefore.
Support for cigarette addiction should focus on the withdrawal syndrome (responsible for immediate failure in quitting smoking) and craving (risk of relapse in the future).
Medication to treat craving
There are preventive treatments for craving. Studies showed that Bupropion was successful in reducing craving and that it was more effective in treating homozygous patients with an A2 allele of the DRD2 gene (dopamine D2 receptor). (7) (8). The SR (sustained release) form of Bupropion has proven helpful in addiction to non-smoked tobacco. (9) The nicotine substitute allows craving symptoms to subside. (10) One study showed that oral forms with a high dose of nicotine substitute was more effective in reducing craving in the more dependent smokers. (11) It seems that high dose patches further limit craving, without stopping it completely however, nor the response to the signal that invokes craving. (12) (13) However, the association of different galenical forms of nicotine substitute help control craving. (14) Varenicline has also proven to be helpful in managing craving, and is even more effective than Bupropion. (15) Varenicline/Bupropion or Varenicline/TNS combinations are more effective in managing craving than monotherapies. (16) (17)
Therapeutic strategies are still being developed for quitting smoking in general, including the management of tobacco craving. In trials, selective monoamine oxydase inhibitors (MAOIs) have been shown to be effective against withdrawal symptoms and in controlling craving. (18) Topiramate, a glutamate GABAergic transmission inhibitor, is a treatment which has proven beneficial against craving in certain studies. (19) The GABAB agonists (Baclofen, Gababentin) are potentially effective in the management of craving. (20) A trial of the D3 receptor antagonists of Dopamine showed a reduction in craving. (21) Olanzapine (antagonist of various receptors) does not mitigate the effect of tobacco craving but does reduce the reactive stimuli that cause the craving. (22) The benefit of Naltrexone, an opioid antagonist, in quitting smoking is unclear. It seems to help in limiting the craving (and weight gain) in the case of women. (23)
There are other channels of therapeutic research taking place. One concerns hypocretin (orexin) and leptin, two peptides. Hypocretin 1 and 2 or (Hcrt-1 and Hcrt-2) or orexin A and B are two neuropeptides synthesised by the neurons in the lateral hypothalamus. Recent studies have suggested an implication of the Hcrt system in addiction and in particular in the phenomenon of craving. A negative correlation has been shown between a plasma concentration of orexin and nicotine craving and a positive association between leptin and craving. (24) Various random controlled studies have underlined that repetitive transcranial magnetic stimulation results in a reduction of craving. (25) (26) Other possible treatments: an action focused on the receptors or sub-units of nAChRs (Acetylcholine receptors). (27)
Non-medicated solutions for craving
To treat craving it is necessary to first work on the factors that increase or decrease the sense of craving. Examples of factors that increase craving: exposure to symptoms, lack of sleep, food restriction, susceptibility… The factors that decrease craving are motivation, food, relaxation and exercise, the treatment of susceptibility and coping strategies. The latter consist in identifying the situations of risk for craving, avoiding exposure to these risks, preparing a response to craving and getting support from those around you and support groups. The relief of craving can also be achieved through the treatment of anxiety and depressive disorders, by taking other psychoactive substances against impulsiveness, as well as risk factors that cause craving.
Cognitive behavioural therapy (CBT) has been shown to be effective in controlling craving. (28) The techniques of cognitive behavioural therapy are aimed at establishing coping strategies, amongst others. Learning and then mastering these techniques leads to increased confidence for the smoker in their capacity to reach their goal of quitting smoking. Examples of cognitive behavioural strategies used to overcome the compulsive desire to smoke:
- Controlling the stimulus: recognizing the trigger situations (seeing others smoking, fatigue, drinking alcohol…) and putting stimulus control strategies in place, through avoidance (avoiding contact with smokers for example), substitution (non-alcoholic drinks instead of alcohol for example) and change (drinking coffee in another place and at another time…).
- Establishing cognitive strategies: remembering that the urges are short-lived and that they will stop, repeating the list of motivations for quitting, thinking about something pleasant, self-encouragement etc.
- Establishing behavioural strategies: changing the context, throwing yourself into a quick activity, doing relaxation breathing exercises, speaking to someone who is supportive…
Other non-medicated solutions can also help to control the urge to smoke. A systematic review of the literature as well as a recent meta-analysis have shown that physical exercise reduces craving. (29) A five minute session of physical activity results in a reduction in the craving sensation identical to that obtained with an oral nicotine substitute. (30)
Various studies have shown that the use of electronic cigarettes has a beneficial effect on craving. One study from 2013 showed that the use of electronic cigarettes had a beneficial effect on craving. (31)
A recently published study also concluded that electronic cigarettes effectively reduce craving, particularly in the case of the most dependents smokers. The best result is attained when strong material is used and there is a high nicotine level in the e-liquid. (32)
Long-term nicotine substitution could similarly be a solution to manage craving, such as in non-smoked tobacco like snus.
Continued research on the craving mechanism is still needed. By better understanding craving it will be possible to develop specific treatments for craving in order to help quit smoking.