A new study by Adrianna Mendrek of the University of Montreal and its affiliated Institut universitaire en santé mentale de Montréal, published in Psychiatry Journal, suggests the menstrual cycle may have an effect on nicotine cravings.
Fewer than one ex-smoker in 10 manages to remain a non-smoker after a year, and women who smoke have a harder time quitting than men, even when they smoke the same amount. In drug studies of nicotine and other substances involving rodents, scientists have observed that female rats become addicted more quickly, and are willing to work harder for the same fix. This observation led Mendrek’s team to conclude that females are perhaps at higher risk of addiction, with sex hormones the reason behind this.
However, the situation is much more complex with humans than with rodents. Each smoker is unique in terms of their tobacco use, personal history, personality, social situation and environment. “Stress, anxiety and depression are probably the more important factors to take into consideration,” says Mendrek. “Having said that, amongst young people, tobacco use by women is unfortunately increasing.”
Uncontrollable urges to smoke stronger during the follicular phase
The study data reveal uncontrollable urges to smoke are stronger at the commencement of the follicular phase of the menstrual cycle, which begins after menstruation. “Hormonal decreases of oestrogen and progesterone possibly deepen the withdrawal syndrome and increase activity of neural circuits associated with craving,” explains Mendrek. Consequently, she believes it may be easier for women to overcome abstinence-related withdrawal symptoms during the mid-luteal phrase, which occurs after ovulation, when levels of oestrogen and progesterone are elevated.
The researchers worked with 34 men and women, each with a 15-plus daily habit. Participants completed questionnaires and 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 in the group were scanned twice: once at the beginning of the follicular phase of their menstrual cycle, and again at the mid-luteal phase. Oestrogen and progesterone levels were also measured.
The researchers led their study with two specific objectives in mind.
- To check if there are gender differences in the neuronal circuits linked to craving.
- To determine if the electro-cortical changes associated with nicotine withdrawal fluctuate in tandem with hormone variations.
No significant differences were found between the men and women in terms of the neuronal circuits. However, the activation patterns for women 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 hippocampus during the luteal phase.
Mendrek hopes the team’s conclusion that taking the menstrual cycle into consideration could help women stop smoking 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 smoker’s profile,” she comments.
Written for the Australian Traditional-Medicine Society (ATMS) by Rosemary Ann Ogilvie from materials released by the Université de Montréal.