Low Vitamin D Linked to Dementia

Vitamin deficiencies are common in the older population.  David J. Llewellyn, from the University of Exeter Medical School (United Kingdom), and colleagues reanalyzed data from the US Cardiovascular Health Study involving 1,658 elderly adults. When the study began in 1993, none of the participants had dementia, heart disease or stroke, and all gave blood samples for analysis.  In 2008, a separate group Cardiovascular Health Study of researchers retested the samples for circulating vitamin D levels.  Whereas most people in the study did have sufficient vitamin D levels in their blood samples, defined as at least 50 nanomoles of the vitamin per liter of blood (nmol/L), about 30% of people had less than that: 419 people were deficient, with more than 25 nmol/L but less than 50, and 70 people were severely deficient, with less than 25 nmol/L. By 1999, 171 people in the study did develop dementia, including 102 cases of Alzheimer’s disease.  The UK team ascertained that people who were severely deficient in vitamin D at the start of the study were more than twice as likely to develop dementia in the coming years than people with sufficient levels.  The study authors write that: “Our results confirm that vitamin D deficiency is associated with a substantially increased risk of all-cause dementia and Alzheimer disease.”