Calcium supplements are commonly recommended to older women to ward off bone-related damage such as osteoporosis. Older adults are recommended to get between 1,000 to 1,200 milligrams of calcium every day but getting this amount through diet can be difficult.
Findings of a small study, however, suggest that in women with history of stroke or white matter lesions (WMLs), taking these supplements may increase the risk of dementia, a neurological condition characterized by confusion and forgetfulness to the point it affects daily life.
For the new study published in the journal Neurology on Aug. 17, Silke Kern, from the University of Gothenburg in Sweden, and colleagues looked at the data of 700 women between 70 and 92 years old who did not have dementia.
The participants did a range of psychiatric and cognitive tests that included an assessment of their memory and reasoning skills at the start of the research and after five years.
At the start of the study, 98 of the participants were taking calcium supplements and 54 had a history of stroke. Over the study period, 54 more women had stroke and 59 developed dementia. Of those who had brain scans, 71 percent had white matter lesions, which indicate mini strokes and other disorders affecting the flow of blood to the brain.
The researchers found that the women who took calcium supplements had twice the risk of dementia compared with women who did not. The elevated risk is limited to those who had stroke or other signs of an existing cerebrovascular disease.
In women who had stroke, the risk for dementia was nearly seven times higher if they took calcium supplements than if they did not.
"Calcium supplementation may increase the risk of developing dementia in elderly women with cerebrovascular disease," the researchers concluded in their study.
The researchers are not certain why taking calcium supplements appears to be associated with increased risk for dementia but it is possible that the supplements affect blood vessels and potentially alter blood flow in these vessels. Earlier research has already linked blood vessel problems with increased risk for dementia. The findings of the study though need to be confirmed by further studies.
Experts also said that the result of the study will not likely change clinical practice.
"Osteoporosis is highly prevalent, and fractures, falls and the disability that come from falls will outweigh changing frequency of prescribing calcium supplements," said Neelum Aggarwal, from Rush University Medical Center in Chicago, who was not involved in the study.