To ward off Alzheimer

An adult brain contains about 100 billion nerve cells, or neurons, 
with branches that connect at more than 100 trillion points.  
Neurons are the chief type of cell destroyed
by Alzheimer's disease.
(http://www.alz.org/brain/05.asp)

It's reported that subtle signs of Alzheimer's have been observed in people even their thirties and forties. (Learn the brain basic anatomy and how the Alzheimer disease affects the brain.) "But genetics is only one third of what predicts brain ageing, the other two-thirds is environment and the lifestyle choices we make, and there is a lot we can do to keep our brains young," stated Dr. Gary Small, Professor of Psychiatry and Biobehavioral Sciences at the University of California, Los Angeles (UCLA) Neuropsychiatric Institute.  

I believe these are helpful:

- Being bilingual (June 04)

- Exercising the brain: crossword puzzle (Aug 02) (and sudoko, I add)

- Maintaining physical activity (June 03)

- Study and be educated (http://www.alzforum.org)