Researchers aren’t yet sure of a complete list of factors that cause pulse rates to rise over time. Shenhar-Tsarfaty questioned whether fear of terror could be implicated in that and elevated levels of C-reactive protein, a biomarker that increases in response to inflammation and signals risk for conditions like cancer and heart disease. And when she and her team compared answers to questions about fear of terror to heart rate measurements over time, they found “major contributions to annual pulse increases and effects of inflammation”—despite the fact that nobody surveyed was present at the time of a terror attack.

Shenhar-Tsarfaty is quick to point out that correlation is not causation. “We didn’t prove causality,” she insists. But high fear of terror predicted higher pulse rates in 4.1 percent of the cohort. C-reactive protein markers were higher, too.

“I can’t tell you whether fear of terror will make you die,” she says. But she believes there’s definitely a link—one that she connects to the ongoing stress of terrorism. She points out that residents of Tel Aviv have been subject to violence, war and chaos for over 60 years. She’s now digging deeper into what genetic and physical factors could influence individual responses to ongoing threats. In the future, she hopes this research can be used to inform public response to terror and help individuals become more aware of their degree of fear and its stressful impact on health.