New research provides more evidence that hormonal birth control pills can negatively impact women’s cognitive performance. The study, published in the journal Hormones and Behavior, found that women taking contraceptive pills tend to have reduced perseverance when completing both simple and complex cognitive tasks.

“My colleagues and I first became interested in this topic after learning that women taking hormonal contraceptives don’t experience a spike in cortisol that is typically found after one encounters a stressor. While people usually talk about cortisol as a bad thing, this cortisol spike allows people to adequately meet challenges in their environment,” explained Hannah K. Bradshaw (@HKBradshaw), a PhD candidate in Experimental Psychology at Texas Christian University and corresponding author of the study.

“After we started looking through the literature, we also found that, compared to non-users, women taking hormonal contraceptives exhibit decrements in brain areas that play an important role in learning, attention, and memory.”

“For instance, compared to non-users, women taking hormonal contraceptives have decreased hippocampal volume. This led us to wonder whether hormonal contraceptive use is associated with differences in perseverance and performance on simple and challenging cognitive tasks that one might encounter in their day-to-day lives.”

In two studies, 324 female undergraduates completed various cognitive tests as the researchers timed them. Roughly half of the participants had been on hormonal birth control for at least two months, while the remainder had not used hormonal birth control for at least three months.

In the first study, participants completed a simple spot-the-difference task in which they were shown two similar images and asked to find 10 subtle differences. In the second study, participants completed more complex mathematical problems and word scramble problems from the Graduate Record Examinations (GRE) test.

The researchers found that women on hormonal birth control tended to spend less time on the problems, which in turn was associated with their relatively worse performance on all of the cognitive tasks.

“Our data suggest that hormonal contraceptive use is associated with decreased perseverance on both simple and challenging cognitive tasks. These differences in perseverance drove decrements in performance. That is, women taking hormonal contraceptives performed worse on these tasks than non-users because they spent less time on the tasks,” Bradshaw told PsyPost.

“The major takeaway here is that hormonal contraceptive use carries a myriad of consequences beyond mere pregnancy prevention; additional research is desperately needed to more fully understand what these consequences may be.”

The study — like all research — includes some limitations.

Randomized experiments are the gold standard in scientific research, but there are obvious problems with trying to randomly assign women to receive hormonal birth control. “We didn’t randomly assign women to the hormonal contraceptives (vs. non-user) group, so it’s possible that our effects may, in part, be due to previously existing differences between women,” Bradshaw explained.

“Secondly, hormonal contraceptives can include different hormones and various ratios of these hormones. We didn’t collect information about this, so it’s impossible to know what specific hormones or hormonal ratios are responsible for our results. Future research is needed to address these limitations.”

The findings may have important implications for women, but the real-world impact of decreased perseverance is unclear. Future research is needed to help “understand how hormonal contraceptive use might influence women’s perseverance in their education, careers, and relationships,” Bradshaw said.

“My colleagues and I don’t have an anti-birth control agenda. By enabling women to take control of their fertility, hormonal contraceptives have helped women meet their educational and career goals,” she added.

“However, it’s important that we understand the unintended consequences associated with hormonal contraceptive use. Millions of women worldwide take hormonal contraceptives. While several women complain about negative emotional and mental side effects, their concerns are largely written off. We need to be less cavalier with women’s health and women’s hormones.”

The study, “Hormonal contraceptive use predicts decreased perseverance and therefore performance on some simple and challenging cognitive tasks“, was authored by Hannah K. Bradshaw, Summer Mengelkoch, and Sarah E. Hill.