Taking vitamins and going on walks can help slow cognitive decline in aging brains. Studies out last week found that a daily multivitamin can effectively take three years off your brain's age when it comes to memory. Similarly, researchers say taking 30 minute walks three or four times a week can lead to better memory. The studies were done over three years by researchers at Columbia and Harvard medical schools and the New York State Psychiatric Institute. Those with underlying heart disease saw the most benefit.