We think of calcium as an important mineral that helps build strong bones. Of course, there are some negative connotations - calcified aorta, calcification in medium-sized arteries, and calcium-containing kidney stones. But, in general, no one would be worried by a relatively high serum calcium level. Until now . . .

Scientists in the Netherlands have used data from the Rotterdam Study of aging people and the Leiden 85-plus Study to examine the relationship between serum calcium levels and mental functioning (cognitive function). Their findings are published in the Journal of the American Geriatrics Society. There were 4,000 people over 70 in the Rotterdam Study, and 550 over-85-year-olds in the Leiden Study.

In the Rotterdam Study, high serum calcium levels at baseline were linked to worse cognitive function, and the over 75s had a faster rate of decline in the 11-year follow-up period. (This wasn't seen in the younger subjects.)

In the Leiden Study, high serum calcium was associated with worse cognitive function at baseline, but there was no indication of further decline in the next 5 years.

Lab studies have shown that long-term increase in calcium within nerves and brain cells can kill them. But it's not known if raised serum calcium levels can actually damage nerve cells and bran cells. Further research is needed. And people with those diseases that may raise serum calcium - kidney failure, some cancers, and excessive parathyroid gland activity - should consider whether there are options to lower their 'hypercalcemia' .