Reuven Dar
Department of Psychology
Tel Aviv University
Hanan Frenk
Department of Behavioral Sciences
The Academic College of Tel Aviv-Yafo
and
Department of Psychology
Tel Aviv University
Is
nicotine an addictive drug?Raising
this question today would seem preposterous to most scientists and lay
people, smokers and non-smokers alike.If
one adopts the definition of facts as theories that have acquired a status
of unchallenged empirical statements(Lakatos
1970),
nicotine
addiction has become a fact.Countless
research papers begin with variations of the sentences “Nicotine is
the active ingredient in tobacco that leads to addiction”(Soria
et al. 1996,
p. 221) or “The reinforcement provided by nicotine is a necessary component
of the processes that drive smoking behavior”(Donny
et al. 1998,
p. 83), providing, as a sole reference, the 1988 Report of the Surgeon
General (US
Department of Health and Human Services, 1988).
In
a recent book (Frenk & Dar, 2000), we reviewed the research literature
on which the nicotine addiction theory is based.We
argued that the unwavering assuredness in which statements about nicotine
addiction are typically made is entirely unjustified by available data.Extensive
evidence
challenges the accepted belief that nicotine is a major determinant of
smoking and that its presence in tobacco smoke increases the difficulty
of quitting.Ironically, our review
suggests that because of the toxicity of nicotine, its major effect of
on smoking may be to limit rather than to facilitate the habit.
In
the course of working on our book, we were repeatedly struck by the poor
quality of the research we were reviewing.The
most common problem was a lack of adequate controls for viable alternative
explanations of the results.There
was almost no control for prior conditioning, for placebo effects, and
especially for well-documented effects of nicotine that are unrelated to
addiction (e.g., its effect on general activity).In
the absence of such essential control conditions, the results of these
studies cannot be interpreted as demonstrating the purported addictive
nature of nicotine.In most cases,
however, neither the original reports nor the reviews summarizing these
reports acknowledge these methodological shortcomings or their implications
for the validity or generality of the results.It
appears that the great majority of nicotine researchers presuppose,
rather than test, the proposition that nicotine is addicting.
The
“near-consensus” that nicotine is addictive “was enshrined
in the 1988 report of the Surgeon General, which regarded nicotine addictive
in the same sense as drugs such as heroin and cocaine” (Stolerman
and Jarvis, 1995, p.117).This
near-consensus has rarely been challenged since, and was recently reinforced
in a report on nicotine addiction in Britain (Tobacco
Advisory Group of The Royal College of Physicians, 2000).The
report,
which purports to provide an updated and objective review of the evidence
for nicotine addiction, reiterates instead the view canonized by the Surgeon
General.It’s “central conclusion”
repeats the Surgeon General’s (US
Department of Health and Human Services, 1988)
statement almost word to word: (p. 117): “Nicotine is an addictive drug,
and the primary purpose of smoking tobacco is to deliver a dose of nicotine
rapidly to receptors in the brain.”Both
the Surgeon General’s report and its recent British counterpart share a
remarkable lack of eagerness for criticism and appear to have been aimed
as authoritative anti-smoking manifestos rather than as objective scientific
analyses of the nicotine addiction research.We
believe that the near-consensus regarding the nicotine addiction hypothesis,
“enshrined” by the first report and “re-enshrined” by second, has severe
theoretical and practical ramifications.
One
problem, which is both created by the near-consensus and perpetuates it,
is economic in nature.In universities
and research centers, publications are the major criterion for tenure and
promotion.Acceptance of articles
into mainstream journals and procuring of grant support for one’s research
has real and immediate economic consequences.In
a field dominated by consensus, scientists would naturally prefer to write
grant applications and articles that are safely in line with the consensus,
especially when this consensus is the official position of authorities
such as the Surgeon General, the National Institute of Drug Abuse and The
Royal College of Physicians.
Psychological
factors may contribute even more than economical ones to the unquestioned
status of the nicotine addiction thesis.Research
on conformity has demonstrated that consensus stifles not only the expressionof
opposing views, but also non-conforming beliefs and perception, even when
objective reality clearly contradicts the consensual view{Asch
1958 2793 /id}.In
the case of the nicotine addiction hypothesis, its social and moral connotations
increase even further the reluctance of researchers to explore dissenting
views.The word ‘addiction’ is highly
charged with morality and values. “A tobacco smoking habit is bad enough,
but it is even worse when one thinks of it as an addiction”(Akers,
1991,
p. 778).When we discussed our book
with colleagues, a number of them reacted to our views as if they were
tantamount to an endorsement of smoking or a vote of support for the tobacco
industry.Suggesting that nicotine
is not addictive, then, is clearly not politically correct, a fact
that may strongly inhibit potential dissidents.
Modern
philosophy of science considers plurality of views and competition among
research programs an essential attribute of the scientific enterprise (e.g.,Lakatos
and Musgrave, 1970).One
mechanism designed to promote criticism and multiple perspectives is the
process of peer review, which is almost universally applied to grant proposals
and to manuscripts submitted for publication.When
the investigator and the referees share a common bias, however, peer review
loses its advantage, as the referees are likely to be as blind towards
methodological flaws as the experimenter is.When
results are in line with the accepted theory, no alternative accounts of
the data are considered, and both researcher and referee are likely to
consider the predicted results as validating the experimental procedure.
The
well-known philosopher of science, Imre Lakatos (Lakatos,
1977),
noted that scientists “do not abandon a theory merely because facts
contradict it.They normally either
invent some rescue hypothesis to explain what they then call a mere anomaly
or, if they cannot explain the anomaly, they ignore it, and direct their
attention to other problems (p. 4).”The
area of nicotine addiction research is rich in rescue hypotheses and ignored
anomalies.A typical example of a
rescue hypothesis is the postulation that the lack of complete suppression
of smoking withdrawal symptoms by nicotine gum or transdermal patches is
due to insufficient nicotine delivery by these devices (e.g.,Tobacco
Advisory Group of The Royal College of Physicians, 2000).In
appealing to this rescue hypothesis, researchers ignore obvious contradictions,
such as the absence of dose-response curves for suppression of withdrawal
symptoms with these devices or of the successful suppression of withdrawal
symptoms with denicotized cigarettes.An
especially blatant example of ignoring powerful evidence against the nicotine
addiction hypothesis is the inexplicable failure of smoking researchers
to cite the numerous studies that found no sign of re-addiction to nicotine
in ex-smokers who were exposed to nicotine transdermal patches for prolonged
periods.One such study (Pullan
et al., 1994)
was published in the prominent and high-impact New England Journal of
Medicine and was cited in 161 studies on ulcerative colitis.Yet,
despite its high relevance to the nicotine addiction theory, it was cited
in only four smoking-related publications.
The
view that nicotine is addicting, then, was successfully “enshrined” in
the Surgeon General’s Report.The
resulting near-consensus in regard to this hypothesis and its complex social
and political ramifications have created an atmosphere in which objective
exploration of this hypothesis became practically impossible.Indeed,
the possibility that nicotine may not be addictive has rarely been raised
since 1988.The nicotine addiction
thesis has been uncritically adopted not only within the scientific community
but also by the media; in fact, we have never heard a dissenting position
expressed publicly.It is hardly
surprising, therefore, that this view has had a profound effect on public
beliefs regarding the nature of smoking.In
1977 (Eiser
et al., 1977),
“About four out of five non-smokers regarded the average cigarette smoker
as an addict, whereas only about half the smokers saw themselves as addicted
(p.334).”Only
eight years later, the same group (Eiser
et al., 1985)
found that only 25 out of 2,312 subjects (1%) answered the question “How
addicted do you think you are to smoking?” with the answer “Not at all.”
This,
we submit, may be one of the worst effects of the nicotine addiction thesis:
it succeeded in convincing smokers that they are chemically addicted to
smoking.Perceptions and beliefs
can have a critical effect on the success of quitting attempts.An
addiction model inherently places control and responsibility outside the
individual, thus undermining his or her sense of control and self-efficacy.Smokers
who believe that they are addicted perceive quitting as more difficult (Jenks,
1994;Katz
and Singh, 1986;Martin,
1990)
and have less confidence in their ability to achieve complete cessation(Eiser
et al., 1985;Eiser
and Van der Pligt, 1986).Moreover,
these attitudes seem to act as self-fulfilling prophecies, as they are
correlated with shorter duration of cessation attempts and higher relapse
rates (Owen
and Brown, 1991).
The
growth of knowledge depends on an unrelenting attitude of skepticism and
continuous competition between theories and research programs (Lakatos
and Musgrave, 1970).When
theories become “enshrined,” whether or not this move is justified by the
alleged welfare of the public, science is in danger of losing its edge
over religion and propaganda.The
dynamics of near-consensus all but guarantee the stifling of criticism,
suppression of novel ideas and proliferation of sub-standard research.It
is high time to “disenshrine” the nicotine addiction hypothesis and to
encourage an objective and critical re-evaluation of its scientific merits.
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