The article relating better mental abilities with higher levels of vitamin D was encouraging. Elderly people assigned to retirement homes may suffer more than the general population from vitamin D deficiency and its associated illnesses, depression being among them, due to being inside most of the time. Keeping blood levels around 70-80/unit of measure (ng/dcl I think) would be helpful in eliminating this as a cause of mental decline. Supplement levels of 400 units/day are woefully low and should be around 5,000 units /day for those remaining inside most of the time and during the winter especially. Those who watch over these people may have to make extra effort to see that they get the required supplement level.