Are Birth Control Pills Bad for Your Brain?

Despite more than half a century of use, there's still more to learn about the effects of birth control pills on the brain.

Birth control pills have been available for over 50 years (birth control pills are also called oral contraceptives or just "the pill"). Since the first birth control pill was approved in 1960, hundreds of millions of people have used oral contraceptives to prevent pregnancy and regulate their periods, according to Kaiser Permanente, which has been actively involved in research on hormonal contraceptives since the late 1960s.

And yet, scientists know very little about how birth control pills affect our brains.

Little Research on How the Pill Affects the Brain

Even though mood swings are one of the most commonly reported side effects of oral birth control, there's hardly any research into how the pill interacts with our brains. In fact, a 2021 Frontiers in Neuroendocrinology paper called the lack of research on the effects of oral contraceptives on the brain, "one of the largest natural experiments in human history."

"There's really very little research I'm aware of on this topic, despite the fact that the pill has been around for more than half a century," Justin Lehmiller, PhD, a research fellow at the Kinsey Institute and author of Tell Me What You Want, told Health. "The studies that do exist tend to have quite small samples and aren't well suited to determining cause and effect."

The Pill's Hormones and the Brain

Ob-gyn Felice Gersh, MD, author of PCOS SOS: A Gynecologist's Lifeline To Naturally Restore Your Rhythms, Hormones and Happiness, said she felt confident that birth control affects the brain. "To think [birth control] won't affect the brain would actually be ludicrous," said Dr. Gersh. That's because birth control was designed as an endocrine disruptor.

In fact, according to Medline Plus, birth control pills contain man-made (or synthetic) forms of 2 hormones: estrogen and progestin. These hormones are made naturally in a woman's ovaries.

These synthetic hormones, said Dr. Gersh, have some similarities with real hormones but can have different effects. And by essentially "replacing" your body's real progesterone and estrogen with the synthetic versions, the pill may tinker with your brain, said Dr. Gersh. "We do know that hormones are hugely important to brain health and brain function," she said.

Mood Effects of Birth Control Pills

Thanks to the past 50 years of people taking birth control pills, we know that many people on oral contraceptives report anxiety and/or depression as a side effect. Up to 9% of women who take combined hormonal pills report changes in mood, said Kelley T. Saunders, MD, an ob-gyn with Banner University Medicine Women's Institute.

There's also a connection between the pill, the sleep-wake cycle, and mood. Estrogen is involved in maintaining your circadian rhythm, or your internal body clock. Research published in 2014 in Frontiers in Behavioral Neuroscience showed that when that time-keeping gets thrown off—which can affect the sleep-wake cycle, hormone release, eating habits, digestion, and body temperature, among other 24-hour cycles—we're at higher risk for psychiatric illnesses like depression and anxiety.

Birth control may also alter our gut microbiomes, the community of bacteria that live in our stomachs and intestines, said Dr. Gersh, "and we know that the gut microbiome is related to brain function."

If taking birth control changes the population of bacteria in your gut, and the bacteria in your gut affect your brain, then it stands to reason that taking birth control will also alter your brain. Will it change your brain in good ways or bad? That we still don't know, because there is so little research—especially research with large-enough sample sizes to say anything conclusive.

Research also suggests that birth control pills use may affect memory and response to stress, making a user more reactive. One 2020 study published in Hormones and Behavior looked at the effects of oral contraceptives on people during the critical developmental period of puberty and adolescence.

The authors found that oral contraceptive use during puberty/adolescence gives rise to a blunted stress response and alters brain activation during working memory processing. They suggest that oral contraceptive use is related to significant structural changes in brain regions involved in memory and emotional processing. The authors conclude that the study provides an explanation for the increased vulnerability to mood-related mental illness in women after oral contraceptive use.

And a 2019 paper published in Current Psychiatry Reports provided a summary of the most current literature on the effects of oral contraception on women's mood. The authors conclude, based on the evidence available, that it is likely that oral contraceptives can lead to mood-related side effects, particularly in people with a history of previous depressive episodes.

Help for PMS and PMDD

Dr. Saunders said she's also seen birth control actually help some patients with mood disorders such as PMS (premenstrual syndrome) or PMDD (premenstrual dysphoric disorder). Many of us have likely blamed a crabby mood or two on PMS, but PMDD is more severe. It's a condition that causes extreme irritability, depression, or anxiety in the weeks leading up to menstruation.

Birth control is one of the common treatment options for PMDD, said Dr. Saunders. "The fluctuations of natural hormone levels may be contributing to these mood disorders," she said. "And we've seen women with pre-existing PMS and PMDD do better on continuous-use hormonal contraceptives." For some, it seems that a steady level of "fake hormones" is better than up-and-down levels of real ones.

Benefits of Birth Control

Hormonal birth control has, without a doubt, changed lives simply by making it possible to choose when to start a family.

"Overall, oral contraceptives have a number of benefits," said ob-gyn Kecia Gaither, MD, who's also board-certified in maternal-fetal medicine. Those benefits include pregnancy prevention, of course, but also clearing acne, treating severe cramping and heavy bleeding, decreasing symptoms of endometriosis, preventing ovarian cysts, treating symptoms of PCOS, and decreasing the risk of ovarian and endometrial cancer.

As the authors of the Current Psychiatry Report paper state, though it's important to take reports on depressed mood as a potential side effect of oral contraceptives seriously, the reality is that discontinuation of the birth control pill can pose subsequent challenges in family planning. Therefore it's important to weigh the mood-related side effects of oral contraceptives against their profound benefits for safe family planning.

So the first step isn't to drop your birth control. The benefits still seem to outweigh the costs for many. Instead, we need more research about what birth control is really doing to our brains. As Dr. Gersh pointed out, "If we aren't aware of what we're doing, we'll never get quality alternatives."

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