Calcium supplementation linked to stroke-related dementia risk in women
medwireNews: Researchers have a found an association between taking calcium supplements and an increased risk of dementia in women with cerebrovascular disease.
Their results showed that older women with a history of stroke who took calcium supplements had an almost seven times greater risk of developing dementia over 5 years than women who did not take supplements, while those with white matter lesions (WMLs) were three times more likely.
Silke Kern (University of Gothenburg, Sweden) and researchers note that the “association was mainly confined to individuals with cerebrovascular disease”.
Women without stroke or WMLs who took calcium supplements were no more likely to develop dementia than those who did not take such supplements.
“Calcium supplementation might have direct toxic effects on vulnerable neurons, because the increased calcium levels may amplify ischemic cell death and worsen the outcome after cerebrovascular events”, the team suggests.
In all, 700 women aged 70 to 92 years participated in the observational study. All the women were free of dementia at the start of the study in 2000–2001, at which point 98 (14%) were treated with calcium supplementation.
Among the women, 54 had a history of stroke and 54 had a stroke during the 5-year follow-up. Computed tomography scans carried out on 447 participants at baseline, showed WMLs in 316, and at this point they were not associated with calcium supplementation.
Dementia, diagnosed according to DSM-III-R criteria, developed in 59 women, occurring in 14.3% of women taking calcium supplements compared with 7.5% of those who were not. Notably, the most common dementia subtype was vascular or mixed dementia, the odds of which were increased 4.4-fold in women taking calcium supplements.
Among women with a history of stroke, of the 15 who took calcium supplements, six developed dementia, compared with 12 of 93 women who did not. Among women with WMLS, 11 of the 50 who took calcium supplements developed dementia, compared with 22 of 266 who did not.
The researchers note in Neurology, however, that there study was observational and so causality cannot be concluded, and the small size means the findings need to be confirmed.
They also put the seemingly contradictory findings – given that dietary calcium is thought to the protective against vascular disease – down to variations in the changes in serum calcium concentrations.
“Dietary intake does not increase the serum calcium levels to the same extent as supplements”, they report. “In addition, dietary calcium intake involves simultaneous intake of all other components of calcium-containing foods and much lower dosages of calcium than calcium supplements.”
By Lucy Piper
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