Some older women who take calcium supplements commonly recommended to slow down age-related bone loss may face an increased risk of developing dementia, a small study suggests.
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, Swedish researchers reported.
Still, the findings from this observational study don’t prove calcium supplements directly cause dementia. 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.
For the study, the researchers 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.
Increased dementia risk seen only in women with history of a stroke
Overall, women who took calcium supplements were twice as likely to develop dementia as their peers who didn’t.
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.
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.
Limitations of the study include its small size
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.
Singling out calcium is premature, say some experts
It’s also important to realize that when it comes to nutrients and cognitive functioning, the combination of nutrients consumed will be more predictive than one single nutrient like calcium. In other words, cognitive function is most likely affected by a combination of calcium and other nutrients such as phosphorus and magnesium.
To say that only calcium increases the risk of dementia is premature.
Source: Neurology, online August 17, 2016.
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