A recent study concluded that lifelong low selenium levels leads to lower cognitive function. The study was based on rural Chinese where it is possible the soil was selenium depleted.
It seems that almost every week in the past 2 years there has been a publication showing that Vitamin D deficiency may play a role in many major diseases. Here
A study published this week looking at homocysteine levels, folate and B12 showed significant correlation with higher homocysteine levels and low folate and memory decline in high functioning elderly Chinese.