Melissa Dahl reports: On Tuesday morning, kids all over Los Angeles arrived at school only to be told to turn around and go back home. Every last school in the Los Angeles Unified School District was closed on Tuesday as a result of a bomb threat that warned of an impending attack on “not one school, but many schools in the district,” superintendent Ramon Cortines said.

The threat is now thought to have been a hoax, something New York authorities — who received a similar message — had already suspected. “These threats are made to promote fear … we can not allow us to raise the levels of fear,” Police Commissioner William Bratton said. But in some ways, whether or not the threat was real is almost beside the point. Either way, the fear is real, and that alone can be dangerous. The latest medical research suggests that, over the years, simply being afraid of terror — even if you never actually witness any sort of attack — may be enough to trigger measurable, physiological harm.

That finding comes from a study published late last year in the journal Proceedings of the National Academy of Sciences, led by a team of physicians at the Hebrew University of Jerusalem. The researchers gathered 11 years’ worth of data from more than 17,000 healthy Israeli adults, who had completed multiple physical health tests as well as surveys measuring their fear of terror. (For example, they were asked how strongly they worried about a terror strike harming themselves or their family, and how tense they felt when in a crowd.)

Their results showed that those who feared terror the most were also most likely to show signs of poorer cardiovascular health — specifically, a resting heart rate that increased over the years. A person’s resting heart rate — their pulse, in other words — typically decreases with age, and a heart that beats 60 times per minute is considered normal. In contrast, some of the people in this study who feared terrorism the most had a resting heart rate as high as 80 beats per minute. An increased heart rate signals a higher risk for cardiac problems, like heart attacks or strokes, and as the Washington Post noted, previous research has found that people “whose resting heart rate rose by 15 beats per minute were 90 percent more likely to die” over the course of a two-year study. And here’s another striking part of this research: These people in the survey suffered real, physical damage because of their anxiety over terrorism, even though none of them had ever actually witnessed an act of terrorism themselves. [Continue reading…]