Oral birth control could impact fear response in the brain: study

A new study suggests there could be a link between oral birth control and how the brain regulates some emotions.

A team of Canadian researchers set out to determine the long-lasting impacts of the birth control pill and whether it affects how the brain processes fear emotions over time.

More than 150 million women use oral contraceptives worldwide, according to those behind the research. The most common type are contraceptives made of synthetic sex hormones, which prevent pregnancy if taken correctly.

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According to the peer-reviewed study published Tuesday in Frontiers in Endocrinology, sex hormones are known to "modulate" the brain's fear processes.

The research suggests long-term use could "exacerbate" how fear is regulated in some people, giving them more anxiety-related symptoms "such as heartbeat awareness, sympathetic nervous system activities and unpredictable aversiveness."

To understand this, researchers said, they recruited women currently using the pill, those who previously used it, women who never used any form of hormonal conceptive, and men.

What they said they found was that those who were using oral contraceptives had a "thinner" ventromedial prefrontal cortex compared to men.

"This part of the prefrontal cortex is thought to sustain emotion regulation, such as decreasing fear signals in the context of a safe situation," Alexandra Brouillard, a researcher at Université du Québec à Montréal and co-author of the study, said in a news release. "Our result may represent a mechanism by which combined (hormone) oral contraceptives could impair emotion regulation in women."

When prescribed birth control, girls and women are aware of the "various physical side effects," but what is not understood are the impacts on the brain, Brouillard said.

By comparing the various groups who use, used and did not use the pill, researchers said they were able to see the differences in the thickness of certain parts of the brain, which hint towards these less-understood impacts.

Comparing the groups showed who would be at "risk" for being able to control emotions during use, Brouillard said.

Those behind the study said these impacts could be reversible, however, "there is still much to learn."

This team is working on other research that involves the onset and effects of the birth control pill in teenage girls, which could impact reversibility.

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