Adults aged 85 and older with type 2 diabetes who had both depressive symptoms and mild cognitive impairment (MCI) were found to have the lowest vitamin D levels in a new study published in Scientific Reports. While the findings do not prove cause and effect, they suggest vitamin D may be linked to both mood and brain health in very old adults. According to the researchers, every 1 ng/mL increase in vitamin D was associated with about a 23% lower likelihood of having both conditions. However, the researchers stress that this was an observational study, meaning it cannot determine whether low vitamin D contributes to these conditions or simply reflects poorer overall health. Vitamin D levels and other factors associated with depressive symptoms and cognitive impairment in the oldest-old patients with diabetes.