1) Tobacco, being a plant, contains a huge variety of substances
2) Smoke is even more complex. Besides nicotine, tobacco smoke
contains over 4000 different chemicals. This
“cocktail” may be far more effective at causing
addiction than is nicotine alone.
3) Tobacco, in whatever form, whether smoking tobacco, nasal tobacco
snuff, or tobacco snus, is in each case more addictive than nicotine
(see above). This superior addictiveness:
be attributed to any common behaviour or
product type, as behaviours differ by product
and route of absorption. For example, while cigarettes and nasal snuff
gives a rapid effect, snus does not.
be attributed to any one manufacturing processes, or additive, as each
type of tobacco is made in a different way.
be influenced by the social environment – whereas nicotine is
sold as a medicine, in limited dose and for a limited period, tobacco
is used as a lifestyle drug of pleasure.
be reinforced by the rituals of use.
be due to the chemical composition of the tobacco itself at the point
of absorption, the smoke inhaled, the snuff or the snus
substances in tobacco smoke, snuff, and snus, may work to enhance
smoking, and tobacco addiction
A review by ESR and Victoria
scientists1 shows that nicotine can release dopamine, (the pleasure drug)
but nicotine by itself does not have a strong effect. Mono-amine oxidase (MAO), an enzyme that mops up dopamine in
the human and animal brain, is inhibited by substances in tobacco
smoke. In rats sensitized with nicotine, MAO inhibitor substances
greatly reinforce the addictive effects. With less MAO activity, the
dopamine reward from the nicotine will be enhanced and this could
enhance nicotine’s addictiveness.
Smoking reduces MAO. Reduction of MAO-A by
28-38% in smokers’ brain scans, and of MAO-B in smokers’
blood platelets of MAO-B by 40% has been observed, compared with
non-smokers and ex-smokers.
of MAO levels after stopping smoking does not occur overnight. Rather it takes days.2
next step is to identify which substances in tobacco account for this
difference. As the identity of these substances could possibly vary
with the product, the focus naturally falls first on tobacco smoke,
about which more is known.
scientists found that the total
particulate matter (TPM or “tar”) from cigarette smoke was more potent
than nicotine alone in up-regulating nicotine receptors in human neural
found in TPM in reasonable quantity, which can reach the brain, include
Harman and Norharman (also found in coffee)
which inhibit MAO A and MAO B enzymes respectively.
use of NRT (nicotine replacement therapy) or e-cigarettes to increase
cessation success carries little risk of permanent dependency to
electronic cigarettes are not a gateway drug trapping adolescents into
nicotine addiction and tobacco smoking, as some fear. Reasons are:
Few if any adolescents are using e-cigarettes despite adult smokers in UK and USA using them since 2007.
Never smokers rarely develop addiction to
Addiction to nicotine in e-cigarettes is unlikely because the
e-cigarette delivers much less nicotine than nicotine gum.
If e-cigarettes induce any weak nicotine dependency it will not be reinforced, as e-cigarettes lack any
1 Lewis A, Miller JH, Lea RA. Monoamine oxidase and tobacco dependence. Neurotoxicology 2007 Jan;28(1):182-95.
Epub 2006 Jul 21.
2 Gilbert DG, Zuo Y, Browning
RA, Shaw TM, Rabinovich NE, Gilbert-Johnson
AM et al. Platelet monoamine oxidase B
activity changes across 31 days of smoking abstinence. Nicotine Tob Res
3. Ambrose V, Miller JH Dickson SJ, Hampton S,
Truman P, Lea RA, Fowles J. Tobacco
particulate matter is more potent than nicotine at upregulating
nicotinic receptors on SH-SY5Y cells. Nicotine Tob Res. 2007; 9: 793-9.