The menstrual cycle appears to have an effect on
nicotine cravings, according to a new study by
Adrianna Mendrek of the University of Montreal and
its affiliated Institut universitaire en santé
mentale de Montréal.
"Our data reveal that incontrollable urges to smoke
are stronger at the beginning of the follicular
phase that begins after menstruation. Hormonal
decreases of oestrogen and progesterone possibly
deepen the withdrawal syndrome and increase activity
of neural circuits associated with craving," Mendrek
said.
She believes that it could therefore be easier for
women to overcome abstinence-related withdrawal
symptoms during the mid-luteal phase, i.e. after
ovulation, when their levels of oestrogen and
progesterone are elevated, but psycho-social factors
cannot be excluded, as tested women were explicitly
asked in the study about the phase of their
menstrual cycle.
"Taking the menstrual cycle into consideration could
help women to stop smoking," Mendrek said. The
findings were published in Psychiatry Journal.
The researchers came to their conclusion by working
with 34 men and women who each smoke more than 15
cigarettes a day.
They filled out questionnaires and had underwent MRI
brain scans, which were taken while they looked at
either neutral pictures or pictures designed to make
them want to smoke. The women were scanned twice -
once at the beginning of the follicular phase of
their menstrual cycle and then again at the
mid-luteal phase. Oestrogene and progesterone levels
were also measured.
Fewer than one ex-smoker in ten manages to stay that
way after a year, and women who smoke have a harder
time quitting than men, even when they smoke the
same amount.
In drug studies involving rodents (nicotine and
other substances), scientists have observed sex
differences. "Female rats become addicted more
quickly, and are willing to work harder for the same
quantity of dose," Mendrek explained. This
observation led Mendrek's team to conclude that
females are perhaps at higher risk of addiction, and
sex hormones could be the reason why.
The situation is much more difficult to unravel when
it comes to humans. Each smoker is unique in terms
of his or her tobacco use, personal history,
personality, social situation and environment.
"Stress, anxiety and depression are probably the
more important factors to take into consideration,"
Mendrek said. "Having said that, amongst young
people, tobacco use by women is unfortunately
increasing."
The researchers led their study with two specific
objectives in mind.
The first was to check if there are gender
differences in the neuronal circuits linked to
craving.
The second was to determine if the electrocortical
changes associated with nicotine withdrawal
fluctuate in tandem with hormone variations.
No significant differences were found between the
men and women insofar as the neuronal circuits were
concerned. However, the activation patterns for the
females varied considerably over their menstrual
cycle. Certain areas of their frontal, temporal and
parietal cortex revealed greater activation during
the follicular phase, while limited activation was
recorded in the hippocamp during the luteal phase.
Mendrek hopes her conclusions will encourage
researchers to pay greater attention to biology when
designing their research protocols. "A greater
knowledge of the neurobiological mechanisms
governing addiction should enable us to better
target treatment according to the smokers profile,"
she said.
Professor Adrianna Mendrek is affiliated with the
Department of Psychiatry at the University of
Montreal and the Research Centre at the Institut
universitaire en santé mentale de Montréal. Her
department and centre colleagues, Professor Stéphane
Potvin, Josiane Bourque, Laurence Dinh-Williams,
contributed to the findings.
The research received funding from the Fonds de
Recherche du Québec - Santé
For more information
Psychiatry Journal
Clinical Study
Sex Differences and Menstrual Cycle Phase-Dependent
Modulation of Craving for Cigarette: An fMRI Pilot
Study
Université de Montréal
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