Women who took calcium supplements were twice as likely to develop dementia.
Cerebrovascular diseases are conditions caused by problems that affect the blood supply to the brain. The four most common types of cerebrovascular disease are stroke, transient ischemic attack (TIA), subarachnoid hemorrhage, and vascular dementia.
These diseases are the fifth leading cause of death in the United States and increase the risk of developing dementia.
"Osteoporosis is a common problem in the elderly. Because calcium deficiency contributes to osteoporosis, daily calcium intake of 1,000 to 1,200 mg is recommended. Getting this recommended amount through diet alone can be difficult, so calcium supplements are widely used," says study author Silke Kern, M.D., Ph.D. with the University of Gothenburg in Sweden.
"Recently, however, the use of supplements and their effect on health has been questioned," she adds.
The researchers hypothesized that calcium supplementation is associated with an increased risk of dementia, and this association is heightened in individuals already compromised by ischemic cerebrovascular disease.
The team tested their theory using a population of elderly women initially free from dementia. A total of 700 women between the ages of 70-92 were involved in the analysis and were followed for 5 years.
Participants received tests of memory and thinking skills at the beginning and end of the study, and a CT brain scan was performed on 447 participants at the start of the research.
Also examined, was the use of calcium supplements by participants, and whether they received a diagnosis of dementia over the duration of the study.
Calcium use in stroke patients increased dementia risk by seven times
At the beginning of the investigation, a total of 98 women were taking calcium supplements. History of stroke was noted in 54 individuals at the start of the study, and 54 more women experienced stroke, while 59 women developed dementia by the study follow-up.
Of the women who received CT scans, 71 percent had lesions in the white matter - a marker for cerebrovascular disease - of their brain.
Results of the study showed that when compared with women who do not take calcium supplements, women who take calcium supplements are twice as likely to develop dementia. However, the increased risk was only observed in women with cerebrovascular disease.
Moreover, women with a history of stroke who also took calcium supplements were seven times more likely to develop dementia than women with a history of stroke who did not supplement calcium.
The participants who had white matter lesions and took calcium supplements had a three-times increased risk of developing dementia, compared with women with white matter lesions and no calcium supplementation.
Women without a history of stroke and women without white matter lesions had no greater risk of dementia when taking calcium supplements.
Foods containing calcium safe, protective against vascular problems
Overall, out of the 98 women who supplemented with calcium, 14 of them (14 percent) developed dementia, compared with 45 out of 602 women (8 percent) who did not take calcium supplements.
Of the women with a history of stroke who took calcium supplements, six out of 15 of them developed dementia, compared with 12 out of 93 women with a history of stroke who did not take supplements.
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.
"It is important to note that our study is observational, so we cannot assume that calcium supplements cause dementia."
Silke Kern, M.D., Ph.D.
Kern also cautioned that the small nature of the study means that the results cannot be generalized to the overall population; therefore, additional studies need to be conducted to confirm the findings.
Although these findings have been observed in calcium supplements, calcium from foods affects the body differently to calcium supplements and is suggested to be safe and even protective against vascular problems, Kern concludes.