HealthDay News — Taking calcium supplements to prevent osteoporosis may raise an older woman’s risk of dementia, according to a study published online August 17 in Neurology.

The 700 participants were dementia-free and between the ages of 70 and 92 at the onset of the research. The study began in 2000, and researchers followed the women’s health for five years. The participants completed a variety of tests at the beginning and end of the study, including tests of memory and cognition. The researchers also conducted computed tomography brain scans on 447 participants at the start of the study, which revealed that 71 percent of these women had white matter lesions.

A total of 98 women were taking calcium supplements at the start of the study, and 54 women had already experienced a stroke. During follow-up, 54 more women had strokes and another 59 women developed dementia. Dementia risk was seven times higher in female stroke survivors who took calcium supplements, compared to women with a history of stroke who didn’t use the supplements. The risk of dementia also was three times higher in women with white matter brain lesions who took calcium supplements, compared to women with white matter lesions who didn’t take the supplements.

Because the study can’t prove causality, “women with cerebrovascular disease and osteoporosis should discuss this new information with their clinicians,” lead researcher Silke Kern, MD, PhD, a neuropsychiatric researcher at the University of Gothenburg in Sweden, told HealthDay. Kern isn’t sure why calcium supplements might have this effect. Calcium plays a crucial role in cell death, she said, and high levels of calcium in the blood might prompt the early death of neurons. Excess calcium also might somehow affect the blood vessels within the brain.

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