Mood swings, often a symptom of menopause, are extreme and rapid changes in your emotional state. You can be happy one minute and angry the next or depressed for no reason at all. Depression, sadness, frustration, irritation, and anger are the most common emotions linked to mood swings. These emotional changes are because hormonal changes in your body affect the chemistry of your brain. Certain treatments for breast cancer can cause your hormone levels to go up or down, induce menopause, and...