(Bloomberg News) Investors are more likely to suffer from heart attacks and cardiac deaths when market volatility rises, according to Sanford C. Bernstein Ltd. health-care analysts.

A 40 percent fall in the Nasdaq Stock Market was associated with an approximate 36 percent increase in heart attacks in one study, Jack Scannell and fellow analysts at Bernstein in London wrote in a "Halloween Special" report today.

Another study showed that a 5 percent move in the Shanghai Composite Index increased the risk among Shanghai residents by about 17 percent, Scannell said. The findings are comparable to the danger of high-risk heart patients not taking cholesterol- lowering drugs, he said.

In both cases, "it is likely that the excess risk would be concentrated" among investors, he said.

A study published this year in the European Heart Journal showed that heart disease deaths in Shanghai correlated with the size of daily swings in the Shanghai index, Scannell wrote. A study from Duke University published in the Journal of the American College of Cardiology last year identified a similar pattern in the U.S., where the rolling-average rate of heart attacks was inversely linked with the level of the Nasdaq, Scannell wrote.

"The effects on daily cardiac risk of large market moves are as big or bigger than the cardiac drugs that have been exciting analysts in the last few years," Scannell said in an interview.

The risk rates reported in both the Shanghai and the Duke studies, according to a statistical measure called a hazard ratio, compare with that of AstraZeneca Plc's bestselling Crestor cholesterol pill in a 2008 study comparing the drug to a placebo, Bernstein said.

The positive results of the Crestor trial, dubbed Jupiter, helped boost the drug's sales from about $3.6 billion in 2008 to about $5.7 billion last year.

"It is not clear how the risk varies between retail investors and institutional investors," Scannell wrote in an e- mail. "No matter how stressful investment professionals find the job, it may well be the actual elderly savers and pensioners -- the ones at high cardiovascular risk -- who really suffer when markets are volatile."

"A very good bit of advice: If you are a retail investor, don't check the value of your portfolio too often," he wrote.