A new study suggests when giving up smoking, women should perhaps consider the effect their menstrual cycle may have on their ability to resist nicotine craving.

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Researchers found that brain activity linked to cigarette craving varied with menstrual cycle, suggesting resisting nicotine may be easier in some parts of the cycle than others.

The study – led by the University of Montreal in Quebec, Canada – looked at how nicotine craving varies between men and women, and in women, how it fluctuates during the menstrual cycle.

Dr. Adrianna Mendrek, a neuroscientist with the Institut Universitaire en Santé Mentale de Montréal, and colleagues note that we already know something about sex differences in smoking. For example, women tend to become dependent on cigarettes more quickly once they start smoking, and they find it harder to give up.

Animal studies have also shown that females become addicted to nicotine more quickly and are willing to work harder for the same dose.

The team wanted to investigate if one of the reasons women struggle to quit smoking could be because their hormone levels go up and down with their menstrual cycle.

For their study, which is published in the Psychiatry Journal, the investigators set themselves two goals. The first was to look at sex differences in the brain activity of nicotine craving, and the second was to see how that brain activity in women varied across the menstrual cycle.

The team recruited 34 smokers – 15 men and 19 women – and took functional magnetic resonance imaging (fMRI) scans of their brains as they were shown neutral and smoking-related pictures known to elicit craving. All the participants were regularly smoking more than 15 cigarettes a day.

The women underwent the procedure twice – at different points in their menstrual cycle. The first was during the early follicular phase, and the second was during the mid-luteal phase. The researchers also measured their levels of estrogen and progesterone.

The follicular phase is the first half of the menstrual cycle – which starts on day 1 of a period. The phase ends when ovulation occurs in the middle of the menstrual cycle, around day 14. The luteal phase follows ovulation and ends when the cycle comes around again to day 1.

The study did not find any significant differences between men and women in terms of the brain activity associated with cigarette craving.

However, the scans showed that in the women, patterns of craving-related brain activity fluctuated across the menstrual cycle. Parts of the frontal, temporal and parietal lobe were significantly active during the follicular phase, while during luteal phase, only parts of the right hippocampus were active.

Dr. Mendrek says:

Our data reveal that incontrollable urges to smoke are stronger at the beginning of the follicular phase that begins after menstruation. Hormonal decreases of estrogen and progesterone possibly deepen the withdrawal syndrome and increase activity of neural circuits associated with craving.”

Dr. Mendrek suggests women may find it easier to overcome craving for cigarettes during the mid-luteal phase – in the 2 weeks leading up to their next period – when their estrogen and progesterone levels are higher.

However, she also notes that other factors may have a stronger influence than hormones. Smokers vary in their use of tobacco, social situation, environment, personality and history. Dr. Mendrek explains:

“Stress, anxiety and depression are probably the more important factors to take into consideration. Having said that, amongst young people, tobacco use by women is unfortunately increasing.”

She says she hopes the study will encourage researchers to give more consideration to biology when designing addiction studies:

“A greater knowledge of the neurobiological mechanisms governing addiction should enable us to better target treatment according to the smoker’s profile,” she adds.

Funding for the study came from the Fonds de Recherche du Québec – Santé.

In December 2014, Medical News Today learned about a Cochrane review that found e- cigarettes can help smokers quit as effectively as nicotine patches.