According to a large, population based study older patients with very low levels of vitamin D have a greatly increased risk for dementia compared with those with higher levels. The study provides strong evidence of the link between vitamin D and cognition.
The analysis included 1,658 ambulatory and relatively healthy participants from the Cardiovascular Health Study in four US communities (Forsyth County, North Carolina; Sacramento County, California; Washington County, Maryland; and Pittsburgh, Pennsylvania).
Researchers measured vitamin D concentrations from blood samples taken in 1992-1993, and in 2008. Cognition was assessed through repeated MRI examinations, medical records, questionnaires, and annual cognitive assessments over about 6 years.
In a model adjusting for age and season of sampling, participants who were vitamin D deficient had a 51% increased risk for all-cause dementia. Those who were severely deficient had about a 122% increased risk. In this new research, the strength of the association was sustained for participants with incident Alzheimers Disease.
The Alzheimer's Association ascertains that some sort of clinical trial — whether it's with vitamin D supplements, increased sunlight exposure, or a vitamin D–enriched diet — is needed to test the effect on dementia. It is unknown at this point what the appropriate blood level of vitamin D might be to protect against the development of dementia.
According to Dr. Wiancek, seventy five percent of the patients she sees have low Vitamin D levels. "Everyone needs to get there Vitamin D levels checked," she says.
