Terror attack scene in Jerusalem .
(photo credit: MARC ISRAEL SELLEM/THE JERUSALEM POST)
Chronic exposure to terrorism can raise the resting heart rates and increase the risk of natural death, according to a Hebrew University study of more than 17,000 Israelis just published in the Proceedings of the National Academy of Sciences.
It was the first statistics- based study – and the largest of its kind – indicating that fear induced by consistent exposure to the threat of terrorism can lead to negative health consequences and increase the risk of mortality.
It is well-documented that international terrorism outbreaks involve mass psychological trauma, leading to long-term mental health risks to the exposed population.
Previous studies have also shown that in the short term, sudden stressful situations, such as earthquakes can increase people’s heart rates and their risk of having a heart attack. However, whether long-term exposure to the threat of terrorism can lead to physical health risks in the exposed population has until now remained unknown.
Molecular neuroscientist Prof. Hermona Soreq (a member of Israel’s National I-Core Center of Excellence for Mass Trauma Research) and postdoctoral fellow Dr. Shani Shenhar-Tsarfaty aimed at a better understanding of the health risks associated with the fear of terrorism. They examined the factors affecting basal (resting) heart rates and how these rates changed over the years during annual checkups of healthy subjects.
Together with Prof. Yaacov Ritov at HU’s department of statistics and center for rationality, they studied 17,300 healthy subjects who underwent an annual general medical exam including blood tests, heart rate and stress tests at the Tel Aviv’s Sourasky Medical Center each year. The 10,972 men and 6,408 women in the study were apparently healthy employees attending periodic routine health examinations during the years 2002 to 2013.
The questionnaire covered a wide range of occupational, psychological and physical factors, including body mass index, blood pressure, fitness, smoking, psychological well-being, anxiety and fear of terrorism.
“We wanted to test whether fear of terrorism can predict an increase in pulse rate and increased risk of death,” said Soreq. By combining the medical exam data with the questionnaire responses, the researchers found that basal heart rate was affected by physiological characteristics, such as level of physical fitness and inflammation index reflecting the activity of the immune system.
In contrast, an ongoing increase in heart rate was also influenced by psychological characteristics such as fear of terrorism. Through a statistical analysis of 325 different parameters, the researchers found that fear of terrorism was a major contributor to annual increases in resting heart rate, with 4.1 percent of study participants suffering from an elevated fear of terrorism that predicted an increase in their resting heart rates.
While a heartbeat of 60 beats per minute is normal, an increase of up to 70 to 80 beats per minute was observed in subjects who exhibited an increased fear of terrorism. In other words, for people with an elevated fear of terrorism, the heart beats faster and the associated risk of heart disease is higher.
Elevated resting heart rate is a predictor of death from cardiovascular disease and death across all causes.
As people age, the resting heart rate typically decreases from year to year, and people whose heart rate actually increases annually are more susceptible than others to heart attacks and strokes.
The researchers also examined how the brain alerts the body to the expectation of danger. They administered a blood test to examine the function of acetylcholine, a neurotransmitter involved in responses to stress and which acts as a brake to the inflammatory response. The results showed that the fear of terrorism leads to a decline in the function of acetylcholine and thus reduces the body’s ability to defend itself from a heart attack, leading to a greater chance of dying.
“We found that fear of terrorism and existential anxiety may disrupt the control processes using acetylcholine, causing a chronic accelerated heart rate. Together with inflammation, these changes are associated with increased risk of heart attack and stroke,” Soreq said. The researchers also found that levels of C-reactive protein, a biomarker for inflammation, were elevated in those volunteers who fear terrorism and show escalated pulse.
This finding further suggests that long-term exposure to terrorism threats may combine with inflammation to elevate resting heart rates and thus increase the risk of mortality.
The researchers suggest that since information on heart rate and its time-related changes is easy to follow, the findings may be useful in identifying asymptomatic people who could benefit from primary prevention measures designed to limit increases in cardiovascular mortality risk. These could include stimulation of the vagal nerve, anti-inflammatory or anti-cholinesterase medications or physical activity.