Premature death of large quantities of brain cells is what characterizes Dementia. Dementia is a progressive and degenerative disease that causes the patient to experience memory loss and disorientation due to the loss of nerve cells in the brain. This disease will progress over many years. Seventy-five percent of todays elderly age 65 or older are estimated to experience symptoms of this debilitating disease. Generally, dementia will not present itself before the age of 60.