Drinking corn fructose sweetened soda (and eating foods sweetened likewise) disrupts synapse communication in the hippocampus, a brain center devoted to memory and learning. Conversely, omega-3 fatty acid foods (fish, nuts, seeds) benefit these synapses.
Studies also show that people with a genetic propensity towards dementias should minimize intake of all foods that produce glucose. Type III diabetes is popularly known as "diabetes of the brain" / the brain produces its own insulin.
Read:
http://www.medicalnewstoday.com/releases/20838.php
http://www.doctoroz.com/videos/alzheimers-diabetes-brain
http://news.bbc.co.uk/2/hi/health/4315609.stm
http://www.time.com/time/health/article/0,8599,1673236,00.html
