Alzheimer's, a type of dementia, is a progressive disease that affects a person's memory and other important functions which are destroyed over time. It usually affects people over the age of 65 and memory loss is one of the most characteristic symptoms of the disease. But do you know why? A new study, published in the journal Neurology, reveals the reason. According to researchers, an alteration or change in the genes may hasten the process of memory loss and affect the thinking ability in people who are already at the risk of developing Alzheimer's.