US studies in (I believe) 2001, with over 3000 participants, showed: taking one ibuprofen a day reduced the risk of Alzheimer's by 60%.
The study was repeated in Denmark using over 7000 participants and they came up with a statistic that taking one ibuprofen a day reduced the risk of Alzheimer's by 80%. People who already had Alzheimer's showed relief and improvement in memory function by taking 2000 IU vitamin E per day, even though the daily recommended dosage is 15 IU per day. I will try to locate the references.
Note: taking up to five ibuprofen per day can lead to internal problems such as liver damage, so be careful.