Birth control pills may adversely affect the brain’s fear-regulating regions in women, potentially increasing the risk of anxiety and stress-related disorders, according to a recent Canadian study.
The peer-reviewed study out of Quebec and published in Frontiers in Endocrinology on Tuesday found that the ventromedial prefrontal cortex, a brain region critical for regulating fear and emotions, was thinner for women currently taking oral contraceptives versus for men and women who never used the pill.
“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 oral contraceptives could impair emotion regulation in women,” Alexandra Brouillard, a researcher at Université du Québec à Montréal and first author of the study, said in a Tuesday media release.
More than 150 million women worldwide use oral contraceptives, according to 2019 United Nations data. In Canada, 2015 data showed that nearly three-quarters of Canadian women use oral contraceptives at some point during their reproductive lives. Data from the Society of Obstetricians and Gynaecologists of Canada shows that oral contraceptive pill use declined among those aged 15 to 19 from 69 per cent in 2006 to 32 per cent in 2016.
Combination birth control pills are the most common type of oral contraceptive, and they contain forms of the hormones estrogen and progestin. These hormones are known to modulate the brain network involved in fear processes, the authors of the study state.
In order to find the long-lasting effects oral birth control may have on the fear-related brain region, researchers recruited women ages 23 to 35 who were currently using oral birth control, women who used to be on it, women who never used any form of hormonal contraception, and men.
They found that women who were currently using oral birth control had a thinner ventromedial prefrontal cortex.
The researchers also pointed out another finding: the potential reversibility of the impacts of birth control pill use once a person stops taking them. This is because the effect on the ventromedial prefrontal cortex was seen exclusively in current users and not in past users, the study stated.
The ventromedial prefrontal cortex is located in the frontal lobe of the brain and it’s linked to greater fear extinction, lesser fear generalization and resilience following trauma exposure.
“The prefrontal cortex is really what helps us interpret things objectively…. It is quite an important area,” Nafissa Ismail, professor at the University of Ottawa’s School of Psychology, told Global News.
“That’s the area we are going to use to make important decisions, to plan and to manage things. It’s essentially where good reasoning takes place. And here we see that specific nuclei within the prefrontal cortex can be impacted by oral contraceptives.”
Ismail, who has studied the impact oral contraceptives have on the brain, called the study “important” as the data is critical in better understanding women’s health.
“We’re just now starting to realize that there is a possible impact of oral contraceptives on the female brain,” she said.
Ismail and the researchers of the study said although there is no conclusive evidence on the direct impact birth control pills have on the brain, more research is needed in order to better understand potential side effects.
'A highly unknown topic'
Past studies have shown that women are more susceptible to suffering from fear-related psychopathologies than men, including anxiety and stress-related disorders.
For example, a 2022 study published in Frontiers in Neuroendocrinology found that anxiety and depression disorders are twice as prevalent in women as in men and that sex hormones are a critical biological factor contributing to the increased depression and anxiety risk in women.
Because women may be more predisposed to anxiety and depression, the Quebec authors in Frontiers in Endocrinology said birth control pills could “exacerbate” this vulnerability by potentially inducing a thinning of the fear-inhibiting region.
Considering how widespread oral contraceptive use is, it is important to better understand its current and long-term effects on brain anatomy and emotional regulation, the researchers said.
“The objective of our work is not to counter the use of oral contraceptives, but it is important to be aware that the pill can have an effect on the brain. Our aim is to increase scientific interest in women’s health and raise awareness about early prescription of oral contraceptives and brain development, a highly unknown topic,” Brouillard said.
Ismail said it’s already known that hormones may cause structural changes in the female brain. The change “seems to be more drastic” when oral contraceptives are taken early on in development, such as during puberty.
This is why more studies, like the one out of Université du Québec à Montréal, need to be done, she stressed.
“I am not to say that oral contraceptives are bad for our brain,” she added. “It’s just that we need more information. Women need to be informed properly before making any decision related to their health.”
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