Sex Boosts Brain Growth, Study Suggests

Weighing in at an average of 2.7 pounds (1,200 grams), the human brain packs a whopping 100 billion neurons. Every minute, about three soda-cans worth of blood flow through the brain. (Image credit: dreamstime.)

Sex apparently can help the brain grow, according to new findings in rats.

Sexually active rodents also seemed less anxious than virgins, Princeton scientists discovered.

Scientists played matchmaker by giving adult male rats access to sexually receptive females either once daily for two weeks or just once in two weeks. They also measured blood levels of stress hormones known as glucocorticoids, which researchers suspected might lie behind the detrimental effects that unpleasant experiences have on the brain.

When compared with male virgins, both groups of sexually active rats had cell proliferation, or an increase in the number of neurons, in the hippocampus, a part of the brain linked with memory whose cells are especially sensitive to unpleasant experiences. The rats that had more sex also had adult brain cells grow, as well as a rise in the number of connections between brain cells.

However, the rodents that only saw females once in two weeks had elevated levels of stress hormones, while the rats that had regular access showed no increase in the hormones. Sexually experienced rodents also proved less anxious than virgins, in that they were quicker to chomp down on food in unfamiliar environs.

These findings suggest that while stress hormones can be detrimental to the brain, these effects can be overridden if whatever experiences triggered them were pleasant.

The scientists detailed their findings online July 14 in the journal PLoS ONE.

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Charles Q. Choi is a contributing writer for Live Science and Space.com. He covers all things human origins and astronomy as well as physics, animals and general science topics. Charles has a Master of Arts degree from the University of Missouri-Columbia, School of Journalism and a Bachelor of Arts degree from the University of South Florida. Charles has visited every continent on Earth, drinking rancid yak butter tea in Lhasa, snorkeling with sea lions in the Galapagos and even climbing an iceberg in Antarctica.