Vitamin D and Older Adults
More Than Just a Bone Problem?
Vitamin D Deficiency May Be Related to Cognitive Impairment
WHAT WERE THE STUDIES AND WHAT DID THEY SHOW?
A recent issue of Neurology featured 3
studies on the possible link between vitamin D and cognition (or thinking) in older adults.
The first study looked at the possible link between vitamin D levels and cognition in older women.
Dr. Annweiler and coauthors studied 752 women aged 75 years and older who lived in France. Levels of 25(OH)D, the form of vitamin D found in the blood, were measured.
Patients took a cognitive test called Pfeiffer’s Short Portablem Mental State Questionnaire (SPMSQ). In this study, low levels (or deficiency) of vitamin D were defined as a 25(OH)D blood level less than 10 (ng/mL). Cognitive impairment was defined as a score of less than 8 (out of 10 points) on the SPMSQ. Seventeen percent had vitamin D deficiency. Women with vitamin D deficiency had lower scores on the SPMSQ and were more likely to have cognitive impairment than those without vitamin D deficiency.
The authors found that vitamin D deficiency was associated with cognitive impairment in
older women.
The second study looked for links between vitamin D levels, cognition, and strokes in older men and women.
Dr. Buell and coauthors studied 318 men and women between 65 and 99 years old in the Boston area. These patients had low income levels, lower functional status, and need for food or personal care.
The researchers checked 25(OH)D blood levels and did cognitive testing. Patients had pictures taken of the brain using magnetic resonance imaging (MRI). Vitamin D “deficient” was defined as 25(OH)D blood levels less than 10 ng/mL, and vitamin D “insufficient” was defined as 25(OH)D blood levels between 10 and 20 ng/mL. MRI changes in the large or small vessels in the brain were used to show if there were strokes or cerebrovascular disease. Approximately 15% of the patients were vitamin D deficient, and 44% were vitamin D insufficient.
About 24% had dementia. Lower vitamin D levels were linked to dementia and MRI changes in the large and small vessels in the brain. The authors found that those with lower vitamin D levels were more likely to have dementia, strokes, and disease in the blood vessels to the brain.
The final study looked at vitamin D levels and cognition in elderly men.
Dr. Slinin and coauthors studied1,604 men aged 65 years and older in 6 cities. 25(OH)D blood levels were measured, and patients took 2 cognitive tests: the Modified Mini-Mental State Examination (3MS) and a timed test called Trail Making Test Part B (TMTB). The patients were divided into 4 groups, based on 25(OH)D levels.
After considering race and education, there was no link between lower vitamin D levels, lower scores on the 3MS, or longer time to complete the TMTB. The authors found that there was not a link between lower vitamin D levels and cognitive impairment in older men.
WHY ARE THESE STUDIES IMPORTANT? It is well
known that vitamin D deficiency can affect bone
health. However, other research shows a possible link may be linked to cognitive impairment.
WHAT CONCLUSIONS CAN BE MADE? Reviewing these 3 studies shows that the authors studied different groups of people, used different definitions of vitamin D status, and had different tests for cognitive function.
As a result, we cannot be certain about the link between vitamin D deficiency and cognitive changes. More research needs to be performed in both men and women living in the community.
A standard definition of vitamin D deficiency is needed. Patients with vitamin D deficiency should be given more cognitive testing to see which aspects of their thinking are affected.
Once the link between vitamin D deficiency and cognitive impairment is understood, other studies using tests like MRI may help find causes for cognitive problems. Researchers can then find out if vitamin D supplements can prevent or treat cognitive changes that may be linked to vitamin D deficiency.
[edited from Neurology 2010, Jennifer V. Rose Molano, MD.]
