Study Links Low Vitamin D to Cognitive Decline in Adults Over 85 With Diabetes - Video

Can a little sunshine vitamin help protect both your mood and memory after 85? New research says it might.

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.

Researchers evaluated 188 adults with type 2 diabetes, with an average age of 87 years. Participants underwent blood tests to measure serum 25-hydroxyvitamin D levels, along with detailed cognitive and depression assessments using standardized screening tools.

The participants were divided into four groups: those with depressive symptoms alone, mild cognitive impairment alone, both conditions, and a comparison group with neither condition.

The results showed that people with both depression and mild cognitive impairment had the lowest average vitamin D levels, while those without either condition had the highest levels.

Further analysis found that lower vitamin D levels were linked to worse depression scores, poorer cognitive performance, and higher blood sugar levels measured by HbA1c.

Even after adjusting for age, education, diabetes duration, and other medical conditions, lower vitamin D remained independently associated with having both depressive symptoms and mild cognitive impairment. 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. Larger long-term studies and clinical trials are needed before vitamin D supplementation can be recommended as a strategy to prevent or treat depression or cognitive decline in older adults with diabetes.

REFERENCE: Gorska-Ciebiada, M., & Ciebiada, M. (2026). Vitamin D levels and other factors associated with depressive symptoms and cognitive impairment in the oldest-old patients with diabetes. Scientific Reports. DOI: 10.1038/s41598-026-65284-z.