April 16, 2010 (Toronto) -- Two new studies add to evidence that older
people with low levels of vitamin D may be more likely to suffer from cognitive
impairment.
The hope is that vitamin D supplements may be able to slow mental decline -- an
intervention that one research team plans to put to the test this summer.
Vitamin D is best known for helping the body absorb calcium, which restores and
strengthens bone, protecting against fracture.
But vitamin D also seems to have anti-inflammatory effects that may help keep
blood vessels healthy, ensuring nutrient- and oxygen-rich blood flow to brain
cells, says Amie Peterson, MD, of Oregon Health & Science University in
Portland.
In addition, the presence of vitamin D receptors throughout the brain suggests
that it may directly affect brain tissue, she tells WebMD.
Testing Cognitive Impairment
Still, whether vitamin D has a role in memory and cognition is unclear at this
point, Peterson says, and studies have had conflicting results.
To help answer the question, Peterson and colleagues studied about 150 people
aged 70 and older living on their own. Their average age was 85, and about
three-fourths were women.
Participants' vitamin D levels ranged from 9 to 90 nanograms per milliliter of
blood. Levels of 30 or higher are considered normal, according to Peterson.
All participants were given a standard 30-point test that is used to screen for
cognitive impairment.
Results showed that the lower their score on the test, the lower their vitamin D
levels.
The average vitamin D level was 42.8 for the 42 participants with a perfect
score of 30 on the test; 36.7 for the 89 participants who scored between 27 and
29 ("still normal but lower," says Peterson), and 34.8 for the 21 people with
scores of 22 to 26 ("mild cognitive impairment").
The study also showed that lower vitamin D levels were associated with a greater
risk of falling.
This summer, Peterson and colleagues plan to embark on a study of people with
Parkinson's disease to look at the effect of vitamin D supplementation on
cognition, balance, and gait. Still to be tested is whether the intervention
will help older people who are otherwise healthy.
Vitamin D Deficiency Common in Elderly
The second study involved 752 women, aged 75 and older, in France.
A total of 129 of the women had vitamin D levels that were below 10 nanograms
per milliliter, suggesting vitamin D deficiency, which is common among older
women, says Cédric Annweiler, MD, of Angers University Hospital.
Compared to women with higher vitamin D levels, those with levels below 10 were
about twice as likely to have cognitive impairment, as measured by a standard
test of cognitive skills, he tells WebMD.
The researchers plan to follow the women for seven years to see whether those
with low vitamin D levels are more likely to develop Alzheimer's disease or
other dementia, Annweiler says.
Studies like that are needed to answer the question of which comes first:
vitamin D deficiency or cognitive impairment, says David Knopman, MD, a
neurologist at the Mayo Clinic in Rochester, Minn., who was not involved with
the new work.
"People with dementia or cognitive impairment tend to become socially isolated
and less physically active, so they’re less likely to get outside" to get the
benefits of the sun's vitamin-D-producing ultraviolet light, he tells WebMD.
The studies were presented at the annual meeting of the American Academy of
Neurology.
Source : WebMD
