In the genes: Why some women find it so hard to quit
smoking
PARIS: Tiny genetic differences among women make it far easier for
some to give up smoking using nicotine patches, according to a
study published online Friday by the British Medical Journal
(BMJ).
Women who have variations of a gene that controls dopamine, a
chemical that is critical for the sensation of reward, are twice as
likely to stub out smoking compared with counterparts who do not
have this variant.
The Oxford University study monitored a large group of men and
women, heavy smokers who puffed on at least 15 cigarettes a
day.
They carried out biochemical tests -- measuring carbon monoxide
concentrations in their breath and saliva levels of cotinine, a
trace chemical from smoking -- to confirm whether they had quit or
not.
The volunteers either got nicotine patches over 12 weeks or dummy
lookalike patch and were monitored a week, three months, half a
year, a year and then eight years after the programme.
At the eight-year stage, they also gave blood samples, which were
scanned for a gene called DRD2 32806, to see whether it contained
two minor variants, CT or TT, or the more common variant, CC.
Forty-one percent of the recruits, men or women, had the CT or TT
genotypes, and the rest had CC.
Women with the CC variant who took the patches were nearly half as
successful in stopping smoking, and staying off tobacco, compared
with women with the less common CT or TT variants.
But there was no difference at all in the success rate among
men.
The findings are important, because they prove that, besides
willpower, genes and gender can play a big factor in whether
nicotine patches will work or not.
The gene in question controls the brain's uptake of dopamine, a
substance that plays a role in the chemical cascade that leads to
the sensation of pleasure.
The nicotine replacement therapy took place in 1991-2 and involved
1,625 participants.
Eight years later, 1,532 were still alive, of whom 752 gave a blood
sample.
According to a study published in The Lancet last September,
smoking kills around five million people a year, with female
smokers and smokers in the developing countries the most vulnerable
group. - AFP
