Saturday, January 02, 2010

Vitamin D and older adults: More than just a bone problem?

I like the last sentence below. The Buell et al study was of very elderly people so is of limited generalizability and may suggest that vitamin D deficiency is just one aspect of poor health and diet. The same applies to the Anweiler study

This issue of Neurology features 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 coauthors1 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 Portable 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 coauthors3 studied 1,604 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.

It is well known that vitamin D deficiency can affect bone health. However, other research shows a possible link between vitamin D deficiency and other disorders. These can include heart disease and diabetes.4 Two out of 3 studies in this issue found that vitamin D deficiency may be linked to cognitive impairment.

The table 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.


Taking herbal supplement to ward off memory problems in old age 'a waste of time'

Thousands of people who take a herbal supplement to ward off memory problems in old age are wasting their time, according to new research. Elderly people who took Ginkgo biloba every day for six years had as many difficulties with recall as those who took a fake supplement, the largest study of its kind has shown.

At least 100,000 people in Britain are thought to regularly take the supplement, which has been widely credited with improving memory and concentration. Made from the leaves of the Ginkgo tree, the Chinese herbal remedy has been used as a traditional medicine for centuries. It is thought to contain chemicals which help the flow of blood around the body, which advocates believe will help protect the brain against decline.

But the researchers who carried out the latest study warned that the supplement appeared to have no effect on warding off age-related memory problems. Beth Snitz, from the University of Pittsburgh, who led the study, said: “Ginkgo biloba is marketed widely and used with the hope of improving, preventing, or delaying cognitive impairment associated with ageing and neurodegenerative disorders such as Alzheimer's disease. “We (found) no evidence that Ginkgo biloba slows the rate of cognitive decline in older adults.”

For the study the team followed 3,069 volunteers, all of whom were aged between 72 and 96 years old and were given either a dose of the herbal supplement or a placebo twice a day for more than six years. The findings are published in the Journal of the American Medical Association (JAMA).


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