New evidence and theories about why people smoke

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New evidence and theories about why people smoke

• Robert West
• University College London
• March 2008

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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

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Cigarette addiction in England
See www.smokinginengland.info
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How can cigarette addiction be assessed in
smokers? The FTND
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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

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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

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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

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The mesolimbic dopamine pathway
The central reward pathway
Nucleus accumbens (NAcc)
Ventral tegmental area
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Drug actions on the mesolimbic pathway
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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

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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

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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

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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

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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

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Motivation to smoke
Smoking
Impulse to smoke
Cues/triggers
Want to smoke
Need to smoke
Anticipated pleasure/ satisfaction
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
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Mechanisms of nicotine addiction 4 Weakened
impulse control

• After repeated nicotine exposure, there may be a
  reduction in the ability to inhibit responses

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Inhibition of smoking
Not smoking
Inhibition
Cues/triggers
Want not to smoke
Need not to smoke
Anticipated praise
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
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Smokers reasons for smoking

• 928 smokers in clinic asked to rate importance of
  various motives
• Enjoyment, boredom relief and stress relief are
  highest
• But none of them predict relapse
• Enjoyment of smoking predicts not attempting to
  stop but is not related to ability to maintain
  abstinence

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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

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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

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The future

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