New evidence and theories about why people smoke

1. New evidence and theories about why people smoke Robert West University College London March 2008

2. Outline • Cigarette addiction in the UK • The common-sense model of why people smoke • A fuller understanding of human motivation • Mechanisms of addiction to cigarettes and the role of nicotine • Psychological factors in why people smoke • The process of smoking cessation • Implications for interventions to promote smoking cessation

3. Cigarette addiction in England See www.smokinginengland.info

4. How can cigarette addiction be assessed in smokers? The FTND

5. The common sense model of smoking • People do what they most desire at a given moment • What keeps them smoking is that: • enjoyment of smoking and needs met by smoking put them off trying to stop despite the health concerns and cost • when they try to stop, the anticipated enjoyment of smoking or relief from unpleasant feelings overwhelm their resolve to remain abstinent • Nicotine is the addictive ingredient in cigarettes because it: • gives an enjoyable feeling • meets certain needs such as stress-relief • relieves withdrawal symptoms caused by nicotine depletion

6. Seven steps to a fuller understanding of human motivation • Many stimuli can generate the impulse to act without the person having any conscious desire or goal • Ability to inhibit impulses because of desires (such as the desire to stick to a plan or avoid unpleasant consequences) vary from person to person and over time as a function of internal and external factors • Desires (feelings of wanting or needing something) can apply as readily to an activity as the expected outcome of that activity • Desires and impulses to engage in an activity are typically more strongly established and resistant to extinction if they are rewarded only intermittently

7. Seven steps to understanding motivation • Beliefs about what is good or bad etc. probably only influence behaviour if they generate desires • Plans/intentions have to be remembered and activate sufficiently strong desires for them to have any effect on behaviour • The exercise of self-control (resisting or generating impulses to act because of desires borne out of plans) is effortful and uses up mental energy

8. The mesolimbic dopamine pathway The central ‘reward’ pathway Nucleus accumbens (NAcc) Ventral tegmental area

9. Drug actions on the mesolimbic pathway

10. Multiple actions of nicotine • A small rapid increase in brain nicotine concentrations (from about 1mg in 10 minutes): • is slightly pleasant to some individuals if there has been no nicotine ingestion for an hour or more (through dopamine release in the NAcc shell) • causes activities that are associated with it to become desired (through dopamine release in the NAcc core) • A low dose of nicotine (about 1mg in humans) makes mildly rewarding stimuli that present at the time, more rewarding (probably through dopamine release in the NAcc shell) • Repeated administration of nicotine leads to: • increased responsiveness of the NAcc shell even if the nicotine is not response contingent • increased responsiveness of the NAcc core only if the nicotine is response contingent • reduction in sensitivity of the NAcc shell to other rewarding stimuli • reduction in tonic level of dopamine in the NAcc

11. What this means psychologically? • Nicotine per se is not particularly addictive: people do not inject it or take it using delivery systems that do not have other rewarding properties • Nicotine from a cigarette makes the cigarette addictive in a way that can only be partially substituted for by other nicotine delivery systems: • the activity of smoking a cigarette becomes desired, including inhaling the smoke • mildly rewarding features of smoking such as the taste and smell take on strongly rewarding properties • Nicotine substitution can relieve some of the need to smoke by raising the tonic depression of NAcc activity; they can do this without themselves being addictive

12. Mechanisms of cigarette addiction 1: Reward and the urge to smoke • When nicotine is absorbed it attaches to nicotinic acetylcholine receptors in the Ventral Tegmental Area (VTA) of the mid brain • This stimulates firing of neurons that project forward to the Nucleus Accumbens (NAcc) • This causes dopamine release in the NAcc • This results in an impulse (urge) to smoke in situations that have been associated with smoking

13. Mechanisms of nicotine addiction 2: Acquired drive • In many smokers, after repeated ingestion of nicotine, the motivational system is altered to create a ‘drive’, somewhat similar to hunger, except that it is for cigarettes • The drive increases in the minutes to hours since the last cigarette and is influenced by triggers, reminders, stress and distractions • The drive is experienced as a need to smoke • It usually reduces over weeks of not smoking but can re-emerge unexpectedly • Relief from this need can be pleasurable and memory of the pleasure makes smokers feeling that they ‘want’ to smoke: the expect to enjoy it

14. Mechanisms of nicotine addiction 3: avoidance and escape • After repeated nicotine exposure, abstinence results in unpleasant withdrawal symptoms including depression • Smokers also report that smoking helps them cope with stress • Adverse mood therefore comes to generate a need to smoke • Smoking intermittently reinforces this and this establishes a strong pattern of behaviour

15. Motivation to smoke Smoking Impulse to smoke Cues/triggers Anticipated pleasure/ satisfaction Want to smoke Need to smoke Nicotine ‘hunger’ Unpleasant mood and physical symptoms Anticipated benefit Reminders Positive evaluations of smoking Smoker ‘identity’ Beliefs about benefits of smoking Plan to smoke Nicotine dependence involves generation of acquired drive, withdrawal symptoms, and direct simulation of impulses through habit learning

16. Mechanisms of nicotine addiction 4: Weakened impulse control • After repeated nicotine exposure, there may be a reduction in the ability to inhibit responses

17. Inhibition of smoking Not smoking Inhibition Cues/triggers Anticipated praise Want not to smoke Need not to smoke Anticipated disgust, guilt or shame Fears about health Anticipated self-respect Positive evaluations of not smoking; negative evaluations of smoking Reminders Beliefs about benefits of not smoking Non-smoker ‘identity’ Plan not to smoke Nicotine dependence probably also involves impairment of impulse control mechanisms undermining response inhibition

18. Smokers’ reasons for smoking • 928 smokers in clinic asked to rate importance of various motives • Enjoyment, boredom relief and stress relief are highest • Butnone of them predict relapse • Enjoyment of smoking predicts not attempting to stop but is not related to ability to maintain abstinence

19. The basic principles of behaviour change Initiation • Dissatisfaction with the present situation • Hope that an alternative will be better • Perceiving a path towards the better alternative Maintenance • Sustaining desire for the new behaviour • Self-regulatory skills to enable that desire to control behaviour in the face of other desires

20. The process of cessation • Smokers feel varying levels of worry about their smoking • Usually this is not enough to provoke a quit attempt but often results in them trying to ‘cut down’ • Occasionally a ‘trigger’ results in hem making a quit attempt • In half these cases the attempt is put into effect immediately; these appear more likely to be successful • Using ‘treatments’ to aid cessation can improve success rates up to 300 percent: • behavioural support • medication

21. The future • Cultural shifts • Reducing occasions when smoking is possible • Better use of NRT • preloading • combination therapy • Better medications for cessation • Alternatives to smoking