Reuters reports on a study showing that exercise and healthy eating may help prevent aging-related memory loss. They specifically cite omega-3 fatty acids and their anti-inflammatory effects; unfortunately, the article mentions only fish oils as a source of these, neglecting the plant based sources which may provide better results.
Anyway, whenever I hear of some new study like this, I always remember the words of Dr. Leonard "Bones" McCoy, when confronted with a purported "immortality" serum: "[L]engthen lives? Poppycock. I can do more for you if you just eat right and exercise regularly.".