More than 150 million women worldwide use oral contraceptives. Combined OCs (COCs), made up of synthetic hormones, are the most common. Sex hormones are also known to modulate the brain network involved in fear processes.

Now a team of researchers in Canada has investigated current and lasting effects of COC use, as well as the role of body-produced and synthetic sex hormones on fear-related brain regions, the neural circuitry via which fear is processed in the brain. They believe that more research could help doctors understand “fear-related psychopathologies predominantly affecting women such as anxiety disorders and post-traumatic stress disorder.”

“In our study, we show that healthy women currently using COCs had a thinner ventromedial prefrontal cortex than men,” said Alexandra Brouillard, of Université du Québec à Montréal and first author of the study published in Frontiers in Endocrinology. “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.”

Emotion regulation and contraceptives

“When prescribed COCs, girls and women are informed of various physical side effects, for example that the hormones they will be taking will abolish their menstrual cycle and prevent ovulation,” Brouillard explained. However, the effects of sex hormones on brain development, which continues into early adulthood, are rarely addressed.

“As we report reduced cortical thickness of the ventromedial prefrontal cortex in COC users compared to men, our result suggests that COCs may confer a risk factor for emotion regulation deficits during their current use,” Brouillard said. The impacts of COC use, however, may be reversible once intake is discontinued.

Much to learn

There is still much to learn when it comes to women’s brains and how they are impacted by COC use. For example, Brouillard and team are currently investigating the impact of age of onset and duration of use to delve further into the potential lasting effects of COCs. Given that many teenage girls start using COCs during adolescence, a sensitive period in brain development, user age might also impact reversibility.