Millions of women around the world use hormonal contraceptives at some point.
Although primarily taken as a method of birth control, many people also use hormonal contraceptives to control a variety of menstrual-related symptoms, from cramps and acne to mood swings.
However, for up to 10% of women, hormonal contraceptives can increase the risk of depression. Hormones, including estrogen and progesterone, are crucial for brain health. So how does changing hormone levels with hormonal contraceptives affect mental health?
I am a researcher studying the neuroscience of stress and emotion-related processes. I also study sex differences in vulnerability and resilience to mental health disorders.
And understanding how hormonal contraceptives affect mood can help researchers predict who will experience positive or negative effects.
In the United States and other Western countries, the most common form of hormonal contraception is “the pill,” a combination of a synthetic estrogen and a synthetic progesterone, two hormones involved in regulating the menstrual cycle, ovulation, and pregnancy.
Estrogen coordinates the scheduled release of other hormones and progesterone maintains the pregnancy.
This may seem counterintuitive: why do the natural hormones needed for pregnancy also prevent pregnancy? And why does taking a hormone reduce levels of that same hormone?
Hormonal cycles are strictly controlled by the hormones themselves. When progesterone levels rise, processes are activated in the cells that stop the production of more progesterone. This is called a negative feedback loop.
The estrogen and progesterone in the daily pill, or other common forms of birth control such as implants or vaginal rings, cause the body to decrease production of those hormones, reducing them to levels seen outside the fertile window of the cycle.
This disrupts the carefully orchestrated hormonal cycle, which is necessary for ovulation, menstruation and pregnancy.
Effects of hormonal contraceptives on the brain
Hormonal contraceptives affect more than just the ovaries and uterus.
The brain, specifically an area called the hypothalamus, controls the timing of ovarian hormone levels. Although they are called “ovarian hormones,” estrogen and progesterone receptors are also present throughout the brain.
Estrogen and progesterone have broad effects on neurons and cellular processes that have nothing to do with reproduction. For example, estrogen plays a role in processes that control memory formation and protects the brain from damage. Progesterone helps regulate emotions.
By changing the levels of these hormones in the brain and body, hormonal contraceptives can modulate mood, for better or worse.
Interaction with stress
Estrogen and progesterone also regulate the stress response – the body’s “fight or flight” response to physical or psychological challenges.
The primary hormone involved in the stress response (cortisol in humans and corticosterone in rodents, abbreviated as CORT) is a metabolic hormone, meaning that increased blood levels of these hormones during stressful conditions result in increased mobilization of energy from fat stores.
The interaction between stress systems and reproductive hormones is a crucial link between mood and hormonal contraceptives, as energy regulation is extremely important during pregnancy.
So what happens to a person’s stress response when they take hormonal contraceptives?
When exposed to a mild stressor—such as putting an arm in cold water, for example, or standing up to give a public speech—women who use hormonal contraceptives show a smaller increase in CORT than people who do not use them.
The researchers observed the same effect in rats and mice: When treated daily with a combination of hormones mimicking the pill, female rats and mice also showed a suppression of the stress response.
Link to depression
Do hormonal contraceptives increase the risk of depression? The short answer is that it varies from person to person. But for most people, probably not.
It is important to note that neither increased nor decreased stress responses are directly related to risk or resilience against depression.
But stress is closely related to mood, and chronic stress substantially increases the risk of depression.
By modifying stress responses, hormonal contraceptives change the risk of depression following stress, resulting in “protection” against depression for many people and “increased risk” for a minority of people.
More than 9 out of 10 people who use hormonal contraceptives will not experience decreased mood or symptoms of depression, and many will experience an improvement in mood.
But researchers don’t yet know who will experience a higher risk. Genetic factors and prior exposure to stress increase the risk of depression, and similar factors appear to contribute to mood changes related to hormonal contraception.
Currently, hormonal contraceptives are often prescribed by trial and error: if one type causes side effects in a patient, another with a different dosage, delivery method or formulation might be better.
But the “try and see” process is inefficient and frustrating, and many people give up rather than switch to a different option.
Identifying specific factors that increase the risk of depression and better communicating the benefits of hormonal contraception beyond birth control may help patients make more informed health care decisions.
*Natalie C. Tronson is an associate professor of psychology at the University of Michigan, United States.
*This article was first published on The Conversation and is reproduced here under a creative commons license. Click here if you want to read the original version.
Keep reading:
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* FDA approves first over-the-counter birth control pill in the US
* These are the reasons why there are no birth control pills for men
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