A new study suggests caffeine might do more for the brain than boost alertness--it may help memory too. The study included more than 100 participants who were caffeine naive, meaning they were not big coffee, tea or cola drinkers. Coffee's caffeine content varies greatly. Most average-size cups contain 160 milligrams. But a 16-ounce cup of Starbucks coffee packs 330 milligrams of caffeine. According to researchers, a dose of at least 200 milligrams of caffeine was needed to enhance memory consolidation.