Study assesses half a million Israelis at risk of developing PTSD due to Oct. 7 and war

Psychology researchers rely on studies done on similar situations to create predictive mathematical model; leading expert questions study’s methodology, believes numbers inflated

Renee Ghert-Zand is the health reporter and a feature writer for The Times of Israel.

Chief Superintendent Avi Amar comforting a distraught IDF soldier near Kibbutz Kfar Aza on October 7, 2023, hours before he was killed. (Israel Police)
Chief Superintendent Avi Amar comforting a distraught IDF soldier near Kibbutz Kfar Aza on October 7, 2023, hours before he was killed. (Israel Police)

A new study predicts that over half a million Israelis are at risk of developing post-traumatic stress disorder in the aftermath of the October 7 Hamas-led attacks and the ensuing war with the terror group in Gaza.

The study, the product of a collaboration of researchers from the Hebrew University of Jerusalem, Columbia University, Shalvata Mental Health Center in Hod Hasharon and the Effective Altruism organization, concludes that some 520,000 — or 5.3 percent of the population — could develop PTSD as a result of the current crisis.

The research, which has not yet been peer-reviewed, focuses only on the south and central areas of the country and does not take into account Hezbollah rocket fire and drone attacks on the north, which began shortly after October 7 and are ongoing.

In addition, the study is not the result of interviews with traumatized Israelis, but rather a meta-analysis based on a review of existing scientific literature on PTSD prevalence following exposure to war and terror. Some of the literature relates to past events in Israel, but most is based on experiences in other countries.

“The entire population was not exposed to a similar degree. Therefore, we created a differential statistical model that depends on the level and extent of exposure to trauma. We divided the population into six different groups in terms of exposure and the model estimates the possibility of PTSD prevalence for each,” explained lead author Dana Katsoty, a PhD candidate in psychology at Hebrew University.

Hebrew University psychology PhD candidate Dana Katsoty (Courtesy)

The first group consists of people who were directly exposed to the October 7 terrorist attacks, specifically those who were at the music festival near Kibbutz Re’im and in the communities around the Gaza Strip and surrounding cities. The model predicts that 31% of this group will develop PTSD.

The second group refers to those who were in close proximity to the terror attacks. This includes people who were in communities and areas within cities that were not infiltrated by Hamas perpetrators. However, the residents were under a severe perceived threat from the invasion of nearby areas and the high probability of the perpetrators invading their homes. These civilians were hiding in bomb shelters and safe rooms for hours and sometimes days.

“This is one of two groups that we could not find sufficient literature to rely on for our model. Therefore, we predicted the same 10% probability of developing PTSD for this group as for people who were under severe rocket attacks. We decided to do this because those who were near the terror attacks were also under severe rocket bombardment,” Katsoty said.

“However, it is important to note that this is considered an underestimation, as such exposure is expected to result in higher PTSD probability. This is one of the reasons we consider the model to be conservative,” she added.

The third group is made up of regular and reserve combat and combat support infantry soldiers. Some of these members of the military were sent into Gaza to fight, while others remained on the Israeli side of the border. Eight percent of this group is predicted to develop PTSD.

The fourth group consists of civilians living under intense exposure to rocket attacks.

The study relies on data from the IDF Home Front Command indicating that cities, towns and other communities up to 40 km (25 miles) from the Gaza Strip were the most exposed during the war. People living this distance from the border have only one minute or less to get to shelter when a rocket siren sounds. According to the model, 10% of this group will show signs of PTSD.

Israelis take cover as a siren sounds a warning of incoming rockets fired from the Gaza Strip in Rehovot, Israel, October 13, 2023. (Dor Kedmi/AP)

The fifth group are civilians who live 40-80 km (25-50 miles) from the Gaza border and are under moderate exposure to rocket attacks. These residents have between one and one-and-a-half minutes to reach shelter.

The sixth group is comprised of people living in communities more than 80 km (50 miles) from Gaza. Although rocket sirens went off in some of these places, the incoming rockets had less of an impact on daily life.

“For the sixth group, our prediction is 2%, but we were unable to find literature that was relevant enough for us to depend on to arrive at a prediction for the fifth group. We assigned the mean of groups four and six to group five, which is 6%.

“The mean was assigned because the fifth group reflected moderate exposure to rockets, and therefore was considered an intermediate level of exposure between the high and low exposure groups,” Katsoty explained.

Katsoty said that the purpose of the model is to provide important information for policymakers and health care system leaders so they can prepare accordingly for treating the huge numbers of Israelis expected to develop post-trauma.

“Even before the war, the country did not have enough psychologists and mental health specialists, including ones trained to treat trauma and PTSD. These high numbers indicate that the public health system needs to think about new paradigms for treating PTSD,” Katsoty said.

“Not everyone will be able to have one-on-one therapy. We need to also consider large-scale interventions that include group therapies, community programs and other broad system-based interventions that can manage to reach more people in need. This is needed not only for PTSD, but also for other mental conditions like anxiety and depression that result from trauma and war,” she said.

The study is in pre-print, meaning it is open for peer review before it is submitted for consideration for journal publication. Given this, The Times of Israel asked an expert who was not involved in the research to provide his feedback as to whether the study provides accurate and useful information for policymakers and mental health care administrators.

Prof. Yair Bar-Haim, head of the National Center for Traumatic Stress and Resilience at Tel Aviv University, January 2024 (Courtesy of TAU)

Although Prof. Yair Bar-Haim, head of the new National Center for Traumatic Stress and Resilience at Tel Aviv University, lauded Katsoty and her colleagues’ study for highlighting the need to plan for PTSD treatment, he questioned its methodology and results.

In an interview with The Times of Israel, Bar-Haim said he believed a more realistic number is around 30,000 new cases of PTSD among Israelis as a result of the October 7 terror attacks and the war. Bar-Haim said that his analysis of existing literature and Israeli experience indicates that only 10% of the approximately 150,000 soldiers and 150,000 civilians directly traumatized by the October 7 terror attacks or heavy  bombardment from Gaza are at risk for PTSD.

“It’s an interesting study, but it has some problems,” he said of the work done by Katsoty and her team.

Using mathematical terms, Bar-Haim noted that with epidemiological studies such as this one, “it all boils down to what you have in the numerator and what you have in the denominator.”

“In terms of the denominator, I have problems with the fact that they broke the population down arbitrarily for the groups related to civilians’ exposure to rocket attacks,” Bar-Haim said.

“The dividing of around 5 million people — half of Israel’s population — from the Gaza border to Herzliya into groups doesn’t work. You can’t lump all these people’s experiences into only three categories. For instance, the cities of Yavne and Rehovot are in the same group in the study. Yavne got maybe one siren a day while Rehovot got many sirens and a rocket slammed into a residential building there,” he said.

Bar-Haim also disagreed with combining soldiers who were stationed or fought inside Gaza with those who stayed in Israel along the border — even if they all belonged to the same battalion. He said he would expect those who were in Gaza to have a considerably higher chance of developing PTSD than those who did not.

IDF soldiers operating in the Gaza Strip in an undated photo released January 2, 2024. (Israel Defense Forces)

He contended that if one wants to know the prevalence of PTSD or the risk of it among those traumatized (“the numerator”), the best way is to actively sample from the population.

“So let’s say you have these six groups that they have in this study, you would go to a large enough representative and repeatedly sample every few months among these populations and see how many cases you get,” Bar-Haim said.

“The team who did the study relied on studies and meta-analyses, including most that were not conducted in Israel. In some cases, they just didn’t have any information, so they [admittedly] came up with a number,” he said.

Bar-Haim insisted that the study’s prediction of more than 500,000 new cases of PTSD was highly inflated.

“Predicting the future is a difficult endeavor. This is probably not the best way to conduct an epidemiological study,” he said.

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