Can Birth Control Affect Memory?

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Though research has shown that women are more likely than men to remember the emotional details of an event, there may be another dividing factor when it comes to memory: birth control.

Scientists know people's hormones shape how their memories form. For instance, our fight-or-flight hormones influence how the brain encodes a specific memory, with traumatic events making more of an impact than everyday activities.

A portion of the brain called the amygdala works on the receiving end of these hormones and is thought to play a central role in making and storing new memories.

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Birth control works by reducing the amount of estrogen and progesterone in a woman's body to limit ovulation, but it's unclear whether these hormones affect how a person recalls an event.

In one study, researchers looked at whether women taking oral contraceptives remembered events from an experiment differently than women with normal menstrual cycles not on birth control. Seventy-two female subjects were recruited for the study, half on the pill and half not.

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Each group watched variations of a slide show story that involved a young boy being hit by a car. Before and throughout the slide show, researchers collected saliva samples to measure alpha-amylase — a chemical that signifies a drop or rise in the fight-or-flight hormone norepinephrine, which increases a person's heart rate during emergencies or stressful situations.

Essentially, they wanted to see whether women responded differently to the slide shows and how they recalled them one week later.

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Seven days after, scientists found the birth control group could recall the gist of the story, but not as many details as the non-birth control group. Women not on the pill seemed to remember more details to the story, including the presence of objects such as a fire hydrant near the scene of the accident in the slide show.

This difference may result from estrogen and progesterone interrupting how stress hormones are perceived by the brain.

Though birth control appears to affect what some women remember, it's important to note this type of contraception doesn't damage memory, as mentioned by one of the study's authors in a press release. Instead, the difference stems from which points are remembered most vividly, not from a deficit of what's remembered.

The experiment is one of many looking at memory between the sexes and whether women are more likely to experience post-traumatic stress disorder than men.

Photo by brains the head/Flickr.com