Here is another recent story on subject. Worth a read. Dr Mercola is suggesting that diet could be preventative.
http://articles.mercola.com/sites/articles/archive/2013/03/31/diet-may-slow-alzheimers.aspx?e_cid=20130331_SNL_Art_1&utm_source=snl&utm_medium=email&utm_content=art1&utm_campaign=20130331
Thank you. A low carb diet was mentioned in the article about coconut oil news story also, though not necessarily recommended.