By David Kiefer, MD

Clinical Assistant Professor, Department of Family Medicine, University of Wisconsin; Clinical Assistant Professor of Medicine, Arizona Center for Integrative Medicine, University of Arizona, Tucson

Dr. Kiefer reports no financial relationships relevant to this field of study.

SYNOPSIS: In this five-year observational study, women who were taking calcium supplementation and who presented with pre-existing cerebrovascular disease were at higher risk of dementia than women not taking extra calcium.

SOURCE: Kern J, Kern S, Blennow K, et al. Calcium supplementation and risk of dementia in women with cerebrovascular disease. Neurology 2016; Aug 17. pii: 10.1212/WNL.0000000000003111.

Calcium is arguably the most commonly supplemented yet most controversial mineral with respect to what it does and does not do. People of all ages need it, some demographic groups more than others, but it is probably important to not ingest too much.1 Despite the myriad clinical trials at one’s disposal, clinicians may wonder how to encourage calcium intake so as to decrease the risk of osteoporosis and fractures, but at the same time avoid increased cancer risk (i.e., prostate) or cardiovascular disease.

The Kern et al study adds to the concern about unrestrained calcium supplementation. For five years, researchers followed 700 women 70-92 years of age and free of dementia. At baseline, and again at the conclusion of the study, the authors conducted extensive physical examination and neuropsychiatric studies. Additionally, researchers collected information about the use of calcium supplementation, including dose and form. In this cohort, 59 women (45 in the non-calcium group, and 14 who had been taking calcium) developed dementia over the course of the study. Also, 98 women reported taking supplemental calcium, putting them at higher risk of developing dementia (odds ratio [OR], 2.10; 95% confidence interval [CI], 1.01-4.37; P = 0.046), although this risk was barely significant when compared to the 602 women who were not taking calcium supplementation. The association was more significant (P = 0.006) for stroke-related dementia (OR, 4.40; CI, 1.54-12.61). Further, subgroup analyses revealed that the higher calcium-related dementia risk occurred in people who had suffered a previous stroke or who, on CT (447 of the 700 patients underwent this imaging at baseline), showed white matter changes, but not in those without these conditions. The authors described how the white matter changes are evidence of cerebrovascular disease.

Essentially, the higher risk of dementia in women taking calcium supplementation occurred mostly in those who already suffered from cerebrovascular disease. These results seem to be in line with some of the concerns about calcium supplementation, or elevated blood calcium levels, and vascular risk.2 This trial showed the most pronounced association with vascular-type dementia, and, as mentioned above, the calcium risk added to pre-existing risk. An observational study like this allows associations to be demonstrated but any cause-effects are merely inferred. Besides, the number of dementia cases (14 in the calcium supplementation group) was very small, possibly compromising the statistical power and accuracy of the findings. Clearly, a well-designed, randomized, controlled trial is indicated to corroborate the calcium-dementia connection. Until then, it would behoove clinicians to be cautious about the use of calcium supplementation in women with a history of cerebrovascular disease because of these concerns about dementia risk.

REFERENCES

  1. Ross AC, Manson JE, Abrams SA, et al. The 2011 Report on Dietary Reference Intakes for Calcium and Vitamin D from the Institute of Medicine: What Clinicians Need to Know. J Clin Endocrinol Metab 2011;96:53-58.
  2. Wang X, Chen H, Ouyang Y, et al. Dietary calcium intake and mortality risk from cardiovascular disease and all causes: A meta-analysis of prospective cohort studies. BMC Med 2014;12:158. doi: 10.1186/s12916-014-0158-6.