(Montreal) A study shows that women taking combined oral contraceptives, better known as birth control pills, have a thinner ventromedial prefrontal cortex than men, a brain region that plays a role in emotion regulation.

The study, published Tuesday in the journal Frontiers in Endocrinology, was carried out by Alexandra Brouillard, doctoral student in psychology at the University of Quebec in Montreal (UQAM), in collaboration with Marie-France Marin, professor in the psychology department from UQAM.

The researcher found that women currently using low-dose “fake estrogen” pills, ethinyl estradiol, have a thinner ventromedial prefrontal cortex than men.

“According to our study, the use of contraceptives could affect brain morphology, but in a reversible manner,” summarizes Ms. Brouillard in an interview.

To carry out this study, she recruited 180 healthy adults aged 23 to 35. They were divided into four groups: women currently using combined oral contraceptives, women who had used this type of contraceptive in the past and who had a natural menstrual cycle at the time of the study, women who had never used hormonal contraceptive, and men.

And all of these people underwent magnetic resonance imaging (MRI).

It should be noted that half of the women who had already used the contraceptive pill and those who had never used a hormonal contraceptive method were examined at the start of their menstrual cycle, and the other half around ovulation, where the rates hormones are higher, says Ms. Brouillard.

“We were able to see inside their brains, and quantify the gray matter that there was in certain key regions of the brain which are important for emotional processes, the expression and regulation of the emotion of fear , more specifically,” explains Ms. Brouillard.

She then looked at “what pill-related parameters may underlie certain findings,” finding that women taking pills with lower doses of ethinyl estradiol had a thinner prefrontal cortex.

What is the ventromedial prefrontal cortex? This is an area of ​​the brain which acts as the “brake of emotions”, which allows one to calm down and regulate oneself, in a context where one should not be in a situation of excessive fear, illustrates the doctoral student.

“On the other hand, we cannot say based on our results whether this thinner region has a concrete impact in the lives of women. Obviously, we think it could be quite deleterious, but at this stage, it’s too early to say if it’s an effect that is clinically significant, since we’re only relying on the gray matter of this region.” , she nuances.

Further studies are needed to determine whether this phenomenon has an impact on women’s mental health and the regulation of their emotions on a daily basis.

However, the study shows that the contraceptive pill would not necessarily have lasting effects on the thickness of the prefrontal cortex, if we stopped taking it.

“On the other hand, as these are adult women who must have stopped contraception for at least a year (in the study), it is possible that there are other factors which could influence the reversibility of the effects,” indicates Ms. Fog. We are looking into the question a little more in depth in a second study that we are currently conducting among these women. »

Do other hormonal methods of contraception such as the contraceptive patch, the contraceptive ring or the hormonal IUD have the same impacts on the brain as the contraceptive pill? This study cannot be used to determine this.

“It remains relevant to study all methods of hormonal contraception, because we alter our hormonal environment, and synthetic or natural hormones can access the brain and influence our cerebral regions,” asserts Ms. Brouillard.

“It’s hard to extrapolate, but one could believe that if the molecules are the same, there could be similar effects,” she added, specifying that the combined contraceptive pill remains the most common method of hormonal contraception. no longer used.