TORONTO — That Israelis inhabit a tense land is not new. Stress levels in Israel have long been found as higher than average, which is unsurprising in a country that’s perennially in a state of war.

Dr. Ora Kofman with a poster outlining her work on residents of Sderot. [Ron Csillag photo]

But now a Canadian-born Israeli expert has hard data to show that among some young people in the western Negev city of Sderot, war-related stress led to damaged cognitive functions and impaired memories.

The impairments were “subtle but significant,” but also temporary, according to research carried out by Ora Kofman, a psychology professor at Ben-Gurion University of the Negev.

The Montreal-born Kofman tested 43 healthy college students aged 20 to 30 — civilians who studied at the local Sapir College and lived in Sderot in 2007. During that year, prior to Israel’s war in Gaza, Qassam rockets fired from Gaza one kilometre away rained on the town at the rate of 15 to 50 a day, with just 15 seconds warning.

Sderot became the symbol for Israeli suffering under the rocket fire. MSNBC reported during the attacks that “nearly everyone” in the town of 20,000 was “traumatized by the frequent sound of air-raid sirens and explosions of incoming projectiles.”

For her study, conducted in the spring of 2008, Kofman divided her subjects into three groups: those who lived, studied and were tested in Sderot; those who lived and studied in Sderot, but were tested in Be’er Sheva, well away from the rocket attacks, and a control group of students who studied, lived and were tested in a safe zone northeast of Sderot.

Impairments and deficits were found only in the first group, suggesting that the trauma was “context-dependent,” says Kofman. Also, the general evidence showed that the students who lived in Sderot were jumpier and more alert than usual.

Kofman, who was in Toronto recently for a conference on frontal lobes, co-hosted by Baycrest, said she wanted to take advantage of the “ongoing chronic stress the students were subject to, and we wanted to look at the effects of real-life stress on their performance of certain cognitive tasks.”

She administered three tests on members of the three groups, none of whom were taking medication or being treated for psychological problems.

But first, the students were subjected to “stress induction.” Kofman asked them how many times they’d been exposed to attacks, how many times they heard rockets falling and if they knew anyone who’d been injured. The students were then shown three pictures of actual rocket attacks and instructed to imagine themselves in those situations.

They then performed unrelated cognitive tests, the point of the exercise being that they had to suppress stronger, dominant emotions, such as fear.

“It’s parallel to what happens when you have to perform any kind of test when you have a strong emotion in the background,” explains Kofman, who earned her doctorate at the University of Toronto. “You sort of have to ignore it, put that aside and continue to function.”

The first test was called verbal list learning, in which the students were told to memorize four lists of fruits and vegetables and one list of furniture. Kofman was looking for something called proactive interference, a process in which past memories interfere with the ability to retain new ones. She didn’t find it.

“We found that the students who were from Sapir and tested in Sapir, where they’d been exposed to the rockets, their learning was just lower overall. We assumed that it might be because they didn’t remember enough words to interfere with subsequent learning.”

The second test timed the students as they switched between responses involving colours and shapes. The students from the first group – those in the danger zone – were found to be more accurate, but slower than the others.

“They were using a different strategy,” Kofman said. “They may just have been used to being more cautious in general.”

The third exercise was the tricky Stroop Test, which forces subjects to inhibit or stop one response in order to say or do something else. For example, it will show the word “blue” in red ink, and subjects are asked to name the colour.

In this task, the students in the danger zone were found to be “significantly less accurate” than those in the other groups, but not slower.

“It’s not that they were being sloppy or distracted, but when it came to incongruent words, they had to suppress the natural tendency to read [and they] made more mistakes,” Kofman explained.

Kofman steers clear of describing the residents of Sderot as suffering from post traumatic stress disorder (PTSD). She cites another study in which the residents of the town were found to have “ongoing traumatic stress response.” The symptoms are similar to PTSD, but the triggers are not in the victim’s past. Rather, they keep happening.

An upside to Kofman’s study shows that the students’ impairments were temporary, as those who were removed from Sderot showed better responses than those who were tested there.

Asked whether her study’s results could be true for everyone in Sderot, Kofman said there would be many variables, but “probably.”