Folic Acid deficiency can cause dementia

Elderly people deficient in a key type of vitamin B could have a three times higher chance of developing dementia, researchers say

Chonnam National University Medical School in Gwangju acknowledged this in their study, noting that "changes in micronutrients could be linked with the other typical signs that precede dementia, including weight loss and low blood pressure.

(Source: http://news.bbc.co.uk/1/hi/health/7226872.stm)