Ionized Calcium and Behavioural Disorders in Older Adults (CALICO Study)

Growing attention is paid to the neurological effects of calcium. While calcium is necessary for neuronal physiology, it appears that high serum calcium concentrations may be toxic to neurons. An analysis of the Rotterdam Study showed that, among older adults, higher concentrations of calcium were associated with greater cognitive disorders and faster cognitive decline. Similarly, delirium and behavioural disorders are reported in older adults with hypercalcemia. In contrast, other studies failed to find any association. For example, in France, an analysis of the EPIDOS study found no association between calcium concentration and cognitive performance. Thus, further studies remain necessary to make firmer conclusions about this link. In particular, it is interesting to note that all previous studies have used the serum concentrations of calcium or corrected calcium, but not yet ionized calcium. This assay is yet more reproducible, more sensitive and more correlated with clinical events. We propose that the non-use of ionized calcium assay may explain, at least in part, the discrepancies between previous studies.