Serum calcium and cognitive function in old age

OBJECTIVES: To determine whether serum calcium is associated with cognitive function in elderly individuals in the general population. DESIGN: Prospective follow-up study of two independent, population-based cohorts. SETTING: The Rotterdam Study (median follow-up 11 years) and the Leiden 85-plus Study (median follow-up 5 years). PARTICIPANTS: Three thousand nine hundred ninety-four individuals, mean age 71, from the Rotterdam Study and 560 individuals, all aged 85, from the Leiden 85-plus Study. MEASUREMENTS: Global cognitive function was assessed in both cohorts using the Mini-Mental State Examination; attention, psychomotor speed, and memory function were assessed in the Leiden 85-plus Study only. Linear regression and linear mixed models were used for statistical analyses. RESULTS: In the Rotterdam Study, high serum calcium was associated with worse global cognitive function at baseline (P<.05) and a faster rate of decline in cognitive function during follow-up (P=.005) in individuals aged 75 and older but not in younger individuals. In the Leiden 85-plus Study, high serum calcium was associated with worse global cognitive function from age 85 through 90 (P<.001). This observation also held for the specific cognitive domains tested (all P<.01). These results did not change when individuals with serum calcium levels greater than normal (>2.55 mmol/L) were excluded from the analyses. CONCLUSION: In the general population, high serum calcium levels are associated with faster decline in cognitive function over the age of 75.