ADELAIDE, Australia — That morning cup of joe may be just what you need to help jumpstart your workday and sharpen your mind. But if you find yourself repeatedly heading over to the coffee pot for refills, you may be actually putting your brain health at risk. Too much coffee can increase the risk of dementia, warns a new study. Drinking six or more cups a day was linked with a 53 percent increased risk of dementia and make stroke more likely, too. Brain imaging reveals that drinking a lot of coffee was also associated with brain shrinkage, say scientists....