The Effect of 'Birth Control Pills' on the Brain.

Confirming what women have known for years, researchers have found that changes in hormone levels can have dramatic effects on the female brain. While the new findings lend weight to the old time-of-the-month cliché, they should also raise concerns about the effects that various hormonal treatments, such as the birth control pill, may have on the brain.

The findings - presented at the 2005 Society for Neuroscience Meeting - show that the "wiring" in the brains of female rats expands and contracts in relation to the amount of estrogen present during the menstrual cycle.