Hormonal changes may actually alter the chemical balance in the brain and trigger some of the mood swings associated with a woman's monthly menstrual cycle, according to a new study. The study suggests that cells in a brain region called the hippocampus generate different types of receptors for the brain chemical GABA during various phases of the menstrual cycle. These changes may affect a woman's susceptibility to anxiety, depression, and seizures. Both estrogen and progesterone have effects on nerve cell activation, but the mechanism behind changes in seizure activity and increased anxiety are unknown, write the researchers. They say their...