Another study has come out showing that older adults with low levels of vitamin D are more likely to have cognitive problems. The six-year study followed 858 adults who were age 65 or older at the beginning of the study. Those who were severely deficient in vitamin D were 60% more likely to have substantial cognitive decline, and 31% more likely to have specific declines in executive function, although there was no association with attention. Vitamin D deficiency is common in older adults in the United States and Europe (levels estimated from 40% to 100%!), and has been implicated in a wide variety of physical disease.
 . Vitamin D and Risk of Cognitive Decline in Elderly Persons. Arch Intern Med [Internet]. 2010 ;170(13):1135 - 1141. Available from: http://archinte.ama-assn.org/cgi/content/abstract/170/13/1135