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 The heightened dementia risk appears limited to women who have had a
stroke or suffer from other disorders that affect blood flow to the
brain, researchers report in the journal Neurology.
“Our study is the first to show a relationship between calcium
supplementation and increased risk for dementia in older women,”
said lead author Dr. Silke Kern of the University of Gothenburg in
Sweden.
Still, the findings from this observational study don’t prove
calcium supplements directly cause dementia, Kern added by email.
Even for women who have had a stroke, it’s too soon to say for sure
whether it makes sense for them to avoid calcium supplements, Kern
noted.
“These findings need to be replicated before any recommendations can
be made,” Kern said.
Millions of women take calcium supplements to strengthen bones made
brittle by osteoporosis, a bone-thinning disorder that typically
develops starting during menopause when the body slows production of
new bone tissue.
For the current study, Kern and colleagues examined data on 700
women between the ages of 70 and 92 who didn’t have dementia.
At the start of the study, and again five years later, women did a
variety of psychiatric and cognitive tests including assessments of
memory and reasoning skills. A subset of about 450 women also got
brain scans.
When the study began, 98 women were taking calcium supplements and
54 participants had already experienced a stroke.
During the study, 54 more women had strokes, and 59 women developed
dementia. Among the women who had brain scans, 71 percent had
so-called white matter lesions, which are signs of mini-strokes and
other disorders that affect blood flow to the brain.
Overall, women who took calcium supplements were twice as likely to
develop dementia as their peers who didn’t, the study found.
But the increased risk appeared limited to people who had a stroke
or other signs of existing cerebrovascular disease.
For women with a history of stroke, the dementia risk was almost
seven times higher if they took calcium supplements than if they
didn’t.
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When women had white matter lesions that can be a precursor to
strokes, the dementia risk was three times greater when they took
calcium supplements.
Among women without a stroke history or white matter lesions,
however, there wasn’t any increased dementia risk associated with
calcium supplements.
Beyond its small size, other limitations of the study include the
lack of follow-up brain scans at the end of the study, which made it
impossible for researchers to assess how calcium supplements may
have influenced the development of white matter lesions or silent
strokes.
In addition, the study didn’t look at how much calcium women got in
their diets, which can affect the body differently than supplements
and is thought to be safe or even protective against blood flow
problems, the authors note.
“Women and the public need to realize that when we talk about
micronutrients –calcium included – and cognitive functioning, we
need to consider that the combination of nutrients will be more
predictive than one nutrient,” said Dr. Neelum Aggarwal, a
researcher at Rush University Medical Center in Chicago who wasn’t
involved in the study.
“For example, calcium, phosphorus and magnesium all are typically
looked at for their effects on multiple organs, and cognitive
functioning will be affected most likely by a combination of these
nutrients,” Aggarwal added by email. “To say that only one nutrient
increases the risk of dementia is premature and more studies need to
look at a combination of nutrients.”
SOURCE: http://bit.ly/NwhhyY Neurology, online August 17, 2016.
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