Calcium supplements could increase the risk of developing dementia among older women who have had a stroke, a new study suggests.
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Among the women who had their brains scanned at the start of the study, 71 percent had lesions on their brains’ white matter, which is a marker for cerebrovascular disease – a group of disorders that affect blood flow in the brain.
The study can’t prove cause-and-effect.
Women who had experienced a stroke and took calcium supplements were seven times as likely to develop dementia, the study found. Subjects who had white-matter lesions were thrice as likely to develop dementia if 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.
Dr Doug Brown, director of research at the Alzheimer’s Society charity, said: “While this research does not show a direct link between calcium supplements and increased dementia risk, it does warrant further investigation”. Because calcium deficiency contributes to osteoporosis, daily calcium intake of 1,000 to 1,200 mg is recommended.
Those who had not had strokes but whose brains showed signs of damage – known as cerebrovascular disease – were also three times more likely to have dementia than those not taking the supplements. Calcium consumed as part of the daily diet can affect the body differently when compared to calcium supplements, the researchers said.
The team tested their theory using a population of elderly women initially free from dementia. The participants were between the ages of 70 and 92 at the start of the study. The study began in 2000, and researchers followed the women’s health for five years. The researchers asked the women if they were regularly taking calcium supplements and tested their memory and thinking skills.
During the course of the study, published in the journal Neurology, 54 more women had strokes and 59 went on to develop dementia. The elevated risk is limited to those who had stroke or other signs of an existing cerebrovascular disease.
“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. However, she says it should prompt a discussion with your healthcare provider. Excess calcium also might somehow affect the blood vessels within the brain.
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.
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Among the 83 women who took calcium supplements with no history of stroke, 18 of them developed dementia, compared with 33 out of the 509 who did not take supplements.
