No prospective study has examined the association between vitamin D and cognitive decline or dementia,… until now.

Researchers in the US, UK, and Italy studied whether low blood levels of 25-hydroxyvitamin D (25[OH]D) are associated with an increased risk of substantial cognitive decline.

First, the details.

  • 858 elderly adults completed interviews, cognitive and medical examinations, and provided blood samples.
  • A decline in reasoning (cognition) was assessed using the Mini-Mental State Examination (MMSE).
    • A substantial decline was defined as at least 3 points.
  • The Trail-Making Tests A (using numbers) and B (uses numbers and letters) were used to evaluate visual attention and task switching.
    • A substantial decline was defined as the worst 10% of the distribution of decline or as discontinued testing.

And, the results.

  • There was substantial cognitive decline in those with severely low 25(OH)D blood levels (less than 25 nmol/L) compared with those who had sufficient levels (greater than 74 nmol/L).
  • The scores of participants who were severely 25(OH)D deficient declined by an additional 0.3 MMSE points per year more than those with sufficient levels of 25(OH)D.
  • The relative risk for substantial decline on Trail-Making Test B (numbers ande letters) was significant, but not with Test A (numbers only).

The bottom line?

The authors concluded, “Low levels of vitamin D were associated with substantial cognitive decline in the elderly population studied over a 6-year period, which raises important new possibilities for treatment and prevention.”

7/16/10 19:43 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.