Sakuma M, et al. - Researchers investigated whether there was an association between serum 25(OH)D levels and cognitive function in a Japanese population. From June 2011 to November 2013, the Project in Sado for Total Health (PROST) study assessed cognitive state and serum vitamin D level for 740 subjects (431 men and 309 women). They used the Mini-Mental State Examination-Japanese version (MMSE-J) and serum 25(OH)D level measurements as assessment tools. According to the findings obtained, low serum 25(OH)D levels were independently correlated with a higher prevalence of cognitive impairment.