Contraceptive pills

(© Studio KIVI -

MONTREAL, Quebec — An alarming new study by Canadian researchers finds that birth control pills may impact how a woman’s brain functions. The study examined the effects of oral contraceptives (OCs) on the thickness of a specific brain region known as the ventromedial prefrontal cortex (vmPFC) and its potential link to emotional regulation in women. Specifically, the team found that birth control pills may alter how women deal with fear.

The vmPFC is a part of the brain that plays a crucial role in regulating emotions and processing fear signals in safe situations. Researchers discovered that women currently using combined oral contraceptives (COCs), which contain synthetic hormones, had a thinner vmPFC compared to men. This finding suggests a possible mechanism through which OC use could hinder emotion regulation in women.

“In our study, we show that healthy women currently using COCs had a thinner ventromedial prefrontal cortex than men,” says study first author Alexandra Brouillard, a researcher at Université du Québec à Montréal, in a media release. “This part of the prefrontal cortex is thought to sustain emotion regulation, such as decreasing fear signals in the context of a safe situation. Our result may represent a mechanism by which COCs could impair emotion regulation in women.”

The study aimed to investigate both the immediate and long-lasting effects of COC use, as well as the role of naturally produced and synthetic sex hormones in brain regions related to fear processing.

While women are typically informed about the physical side-effects of COCs, such as the suppression of the menstrual cycle and ovulation, the study emphasizes the importance of understanding the potential effects of these hormones on brain development, especially in young adults.

Woman holding pill, glass of water

To conduct the research, the team recruited women who were currently using COCs, women who had previously used them but were not at the time of the study, women who had never used hormonal contraception, and men. This comparison allowed them to assess the association between COC use and both current and long-term changes in brain structure, as well as to identify potential sex differences, as women are more susceptible to anxiety and stress-related disorders than men.

The study found that COC users exhibited reduced cortical thickness in the vmPFC when compared to men, suggesting that COCs may increase the risk of emotion regulation deficits during their use. However, researchers also noted that these effects may be reversible upon discontinuation of the contraceptives, as past users did not display the same anatomical changes as current users. Nonetheless, scientists stressed the need for further studies to confirm these findings.

The team is currently exploring the impact of the age of onset and the duration of COC use to gain a deeper understanding of potential long-term effects, especially considering that many teenage girls begin using COCs during a critical period of brain development.

Despite the intriguing findings, researchers cautioned against drawing direct conclusions about the behavioral and psychological impacts of COC use based solely on anatomical changes. They emphasized that their objective is not to discourage the use of COCs but to highlight the importance of considering their potential effects on the brain.

“The objective of our work is not to counter the use of COCs, but it is important to be aware that the pill can have an effect on the brain,” concludes Brouillard. “Our aim is to increase scientific interest in women’s health and raise awareness about early prescription of COCs and brain development, a highly unknown topic.”

The study is published in the journal Frontiers in Endocrinology.

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