The National Institutes of Health is halting a study testing whether Celebrex - or naproxen - would reduce the risk of Alzheimer’s disease.

Both pain relievers are commonly used to treat arthritis.

NIH officials said the study was stopped after three years when it was noticed that patients taking naproxen had a 50 percent greater incidence of heart attack or stroke than patients taking a placebo.

Another factor was the announcement on Monday that advertising for Celebrex was being halted after a study found that high doses of the drug was associated with an increase in heart attack risk.

The Food and Drug Administration says patients who routinely take naproxen should follow the drug directions carefully and consult a doctor if their pain continues.

Naproxen, sold under the brand name Aleve, is the third medicine used for arthritis pain that has been linked to heart problems. Naproxen has been approved for sale, first as a prescription and then as an over-the-counter drug, since 1976.

Manufacturers pulled arthritis drug Vioxx off the shelves on Sept. 30 over concerns about a possible connection to fatal heart problems.

And last week, drug maker Pfizer said the arthritis painkiller Celebrex could increase the risk of a heart attack or a stroke if taken in very large doses. But it says it won’t take Celebrex off the market, although on Monday said it would halt advertising the drug. Federal scientists have halted a study testing Celebrex for cancer prevention.

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