hooked. Smoking is an extremely effective
way of delivering nicotine to the brain. It
is rapidly absorbed through the lungs into
Why is it so hard to quit
the bloodstream, where it is carrieddirectly to the heart and reaches the brainin about 6–10 seconds (akin to an
intravenous injection: Rose et al., 2000).
Because of this direct route, nicotine does
Lynne Dawkins explores the role of nicotine and non-nicotine contributions to
not get a chance to dissipate, so the high
smoking and considers a promising new device for kicking the habit
concentration of nicotine in the lungsfrom a puff on a cigarette remains in theblood as this ‘hit’ (often referred to as a
Smoking is the single most
‘bolus’) until it reaches the brain. Whilst
preventable major cause of illness
addictive, nicotine is relatively safe; it’s
and early death, with nearly one in
five deaths (in those aged 35 or
people a day – or nine people an hour –
above) caused by smoking.
Smoking has a multitude of effects
on health, that most smokers are
carcinogens) that carry the health risks
aware of. So why do more than one
deaths and 14 per cent of all circulatory
in five adults continue to smoke?
And why is it so hard to give up?
smoking. This figure rises to 87 per cent
acetylcholine’ receptors. Many of these are
located on the cell bodies in the ventral
Information Centre: tinyurl.com/cym3apk).
dopamine ‘reward’ pathway that projects
regular smoker loses an average of 10 years
of their life (Doll et al., 2004). That is,
activities (such as eating, drinking, sexual
live beyond 70 years compared to only half
activity, and so on), but addictive drugs
of long-term smokers (Kenny, 2012). If it
can ‘hijack’ this system resulting in faster
other ways of making your life a misery:
(NIDA, 2010). When nicotine activates the
nicotinic receptors in the VTA, it results in
How important is the nicotine delivery in
addictive drugs are positively reinforcing –
smokers are aware of these harmful effects,
why do 21 per cent of the adult population
are more than 95–97 per cent of unaided
quit attempts unsuccessful (Hughes et al.,
awareness, setting up a strong motivational
drive to smoke, which may conflict withconscious thoughts, beliefs and plans.
West, R. (2006). Theory of addiction.
The problem with nicotine
Barrett, S.P. & Darredeau, C. (2012). The
delivery. Tobacco Control, 19
Etter, J.F. & Bullen, C. (2011). Electronic
Corrigall, W.A., Coen, K.M. & Adamson,
Dawkins, L., Turner, J., Hasna, S. & Soar,
satisfaction and perceived efficacy.
male and female smokers. Behavioral
Etter, J.F. & Stapleton, J.A. (2006).
area. Brain Research, 653
Addictive Behaviors, 37
Bullen, C., McRobbie, H., Thornley, S. et
Dawkins, L., Powell, J.H., West, R. et al.
Doll, R., Peto, R., Boreham J. et al.
meta-analysis. Tobacco Control, 15
Hughes, J.R., Keely, J. & Naud, S. (2004).
male British doctors. British Medical
inhibition and executive functioning.
vol 26 no 5
as well as elicit positive subjective effects
individual, that is, they whet the addict’s
(e.g. irritability, depression, restlessness,
contains nicotine (Barrett & Darredeau,
inducing craving and motivation to use.
During a quit attempt, encountering a cue
(the sight or smell of a cigarette) can be
light or a tone; Sorge et al., 2009). So,
likely that craving and a lapse to smoking
nicotine in combination with other salient
Is the smoking habit just about
sensorimotor cues might be a particularly
Although the nicotine content is clearly
a critical component of tobacco addiction,
(Robinson & Berridge, 1993) suggests
context of a particular set of cues (e.g. with
a cup of coffee or tea; the sight and smell
ordinarily mediates how ‘noticeable’ and
‘attention grabbling’ things are in the
drugs such as heroin, cocaine and alcohol
cigarette in the hand) these cues can then,
via classical conditioning, act as ‘secondary
easily activated) because of the repeated
reinforcers’ – they become moderately
a cigarette in one’s hand, are unlikely to be
describe such things as pleasurable. It is
harder to inhibit over-learned tendencies
(Dawkins et al., 2007), makes it extremely
hard for the smoker to resist the urge to
reinforcing (it triggers dopamine release
nicotine is punished (it is associated with
During a quit attempt,
encountering a cue can be
cigarette, the ‘catch’ of smoke in the
learning therefore results in a highly over-
primary reinforcer – nicotine – can come
smoking can alleviate nicotine withdrawal
Robinson, T.E. & Berridge, K.C. (1993).
smokers. Addiction, 99
dose selection for in vivo research.
Hughes, J.R., Rennard, S.I., Fingar, J.R.
et al. (2011). Efficacy of varenicline to
NIDA (2010). Drugs, brains, and behavior:
addiction. Brain Research Reviews,
planning to quit. Nicotine Tobacco
Perkins, KA., Gerlach, D., Vender, J. et al.
Parrot, A.C. & Craig, D. (1995).
Kenny, T. (2012). Smoking: The facts.
British Medical Journal 328
Rose, J.E., Behm, F. M., Westman, E.C. &
Matta, S.G., Balfour, D.J., Benowitz, N.L.
Perkins, K.A., Donny, E. & Caggiula, A.R.
read discuss contribute at
according to the presence of external cuesas well as his or her internal state.
Sensitisation of the dopamine rewardpathway with chronic nicotine useestablishes a heightened desire or cravingfor nicotine, especially in the presence ofsmoking-related stimuli. Thus nicotineaddiction can be thought of as a deeplyentrenched pattern of behaviour underpowerful stimulus control because ofrepeated reward and punishment effects.
Efficacy of currently available
‘quit smoking’ aids
With the considerable evidence that
smoking behaviour is driven by nicotine
addiction and that nicotine itself is
relatively safe, came the introduction of
nicotine replacement therapy (NRT) –
Although the existing literature does not merit a conclusion that e-cigarettes are safe in
absolute terms, they are clearly much safer than tobacco cigarettes
lozenge, inhalator and nasal spray. Therationale is to partially replace the
the drug company suggests that it is three
times better than placebo (Wu et al., 2006)
with a 14 per cent success rate (Hughes et
smoke. Over 100 placebo-controlled trials
cigarette smoking, but also the ‘activity’ of
associated with a number of side-effects,
smoking. If we could manufacture a device
smoker’s chances of quitting successfully
to 6–12 months (see Silagy et al., 2005,
without the CO and tar and
for a meta-analysis). However, given that
suicidal thoughts and an increased risk of
the success rate for unaided quit attempts
is so low, this means that, even with NRT,
the absence of side-effects, is still far from
end in failure (Etter & Stapleton, 2006).
addiction (by replacing it, mimicking it
The electronic cigarette
increasing the availability of noradrenaline
or preventing it from having its rewarding
and dopamine thus mimicking the effect of
nicotine and helping to reduce craving and
deliver nicotine via inhaled vapour. Since
(Roddy, 2004). Champix partially activates
Dragonite) in China, electronic cigarettes
and nicotine withdrawal. It also prevents
nicotine from activating these receptors
denicotinised cigarette (which provides the
sensory and behaviour aspects of smoking,
propylene glycol, flavouring, and varying
Seigel, M. & Cahn, Z. (2010). Evidence
of cigarette smoking. Pharmacology,
suggests e-cigs safer than cigarettes:
stimulus. Psychopharmacology, 207
Biochemistry and Behavior, 67,
administration. Nicotine and Tobacco
Rose, J.E., Salley, A., Behm, F.M. et al.
Vansickel, A.R., Cobb, C.O., Weaver, M.F.,
Silagy, C., Lancaster, T. & Stead, L. et al.
& Eissenberg, T.E. (2010). A clinical
West, R. (2006). Theory of addiction
‘cigarettes’. Cancer Epidemiology,
Wu., P., Wilson, K., Dimoulas, P. & Mills,
Siegel, M. (2011). The rest of the story:
Sorge, R.E., Pierre, V.J. & Clarke, P.B.S.
Vansickel, A.R. & Eissenberg, T. (2012).
vol 26 no 5
times this level (Siegel & Cahn, 2010).
Let’s face it, inhaling any chemical into
differences are consistent with an emerging
‘drawing’ on the device or pressing a
the lungs is likely to be associated with
button. ‘Smoking’ an electronic cigarette
(often referred to as ‘vaping’) therefore
reinforced more by nicotine intake, and in
mimics the act of smoking: the user holds
the device and draws on it like a cigarette;
responses to smoke stimuli (Perkins et al.,
in working memory with nicotine (relative
to placebo) in the whole sample, suggesting
flavouring resembles the taste of inhaled
the literature, Professor Siegel from Boston
that nicotine delivery is at least sufficient
tobacco smoke. In short, it addresses the
absolute terms, they are clearly much safer
than tobacco cigarettes. In fact, ‘the truth
Rose et al., 2010). Furthermore, since no
demonstrated significantly elevated blood
cigarettes’ (Siegel & Cahn, 2010).
achieved via cigarette smoking. This latter
study clearly suggests that e-cigarettes are
Can the e-cigarette help
smokers to quit?
Although a product that delivers nicotine
the nature of vaping and product choice.
smoking cessation address only the former.
The e-cigarette delivers nicotine without
to provide pleasure as well as save lives.
clinical trials have yet to be completed,
a recent large online survey reported over
cigarettes are a highly effective nicotine
cartridges, the properties of the vapour,
90 per cent of users stated that e-cigarette
replacement, such respondents are likely
reduce their cigarette consumption (Etter
& Bullen, 2010). Two published reports
of e-cigarette use in naive users, however,
concern. On balance, however, e-cigarettes
are probably doing people very little harm
raised blood nicotine levels is consistent
and, in all likelihood, doing people a lot of
good if they are using these as a complete
or partial alternative to tobacco smoking.
content analysis of 19 e-cigarette cartridges
with smoking contribute to its reinforcing
What is very apparent is that the potential
University of East London (Dawkins et al.,
causing agents) in some of the cartridges,
as well as inaccurate reporting of nicotine
(placebo) e-cigarette reported comparable
replacement therapies. TSNA levels present
read discuss contribute at
CURRICULO VITAE Lair Geraldo Theodoro Ribeiro, M. D., F.A.C.C. EDUCATION Educational Foundation Machado Sobrinho, Medical School of the Federal University INTERNSHIP AND POSTGRADUATE TRAINING Residency in Cardiology, Pontificia Universidade Catolica of Rio de Janeiro (RJ), Brazil Research Fellow in Medicine, Peter Bent Brigham Hospital and Harvard Medical School, Boston (MA
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