The study was conducted by Adrianna Mendrek of the University of Montreal and its affiliated Institut universitaire en sante mentale de Montreal.
“Our data reveal that incontrollable urges to smoke are stronger at the beginning of the follicular phase that begins after menstruation,” Mendrek said.
“Hormonal decreases of oestrogen and progesterone possibly deepen the withdrawal syndrome and increase activity of neural circuits associated with craving,” Mendrek added.
She believes that it could therefore be easier for women to overcome abstinence-related withdrawal symptoms during the mid-luteal phase, ie 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 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.
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 said.
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 researchers set out to determine whether there are gender differences in the neronal circuits linked to craving.
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.
The findings were published in Psychiatry Journal.
PTI