"We are on the cusp of a tsunami of poor mental health in the region," says Dr. Sandro Galea, dean of the School of Public Health at Boston University. "There is no doubt about that."

Galea is talking about the war in the Middle East, where Hamas attacks have killed more than 1,400 people in Israel and Israel's bombing campaign against Hamas has killed well over 6,500 people in Gaza.

Studies the world over have documented that traumatic events like war and armed conflicts can cause an alarming spike in post-traumatic stress and depression.

In the United States, Galea and his colleagues documented the mental health toll of 9/11 starting about a month after the attacks. They found that of adults living in New York City and neighboring areas in New Jersey and southern Connecticut, 7.5% reported symptoms of post-traumatic stress disorder (PTSD) and nearly 10% reported symptoms of depression. The rates of these symptoms were nearly double the national baseline prevalence of 3.6% for PTSD and 4.9% for depression.

While Galea and his colleagues found that this burden of mental health symptoms declined about 6 months after the attack, a significant minority continued to struggle long-term.

"So about a third of people [went] on to have chronic symptoms," says Galea. "By chronic, I mean, years thereafter."

About 10% of the 70,000 enrollees in the World Trade Center Health Registry who were directly affected by the attack have continued to report symptoms of PTSD over the years.

A surge in calls to Israel's mental health hotline

In Israel and Gaza, people are now coping with the death and kidnapping of loved ones, of watching others die, of trying to stay safe and simply get food and medicine needed to get by. Past studies of mass traumas suggest that they're all at risk of trauma-related mental health problems.

Those who were directly affected by a mass trauma are of course at the greatest risk of developing symptoms of mental illnesses, says Galea: "So somebody who lost a loved one, somebody who lost a limb, was injured in the event, somebody who lost their house in an event."

Those who are mostly likely to struggle with chronic symptoms are people with prior traumas and hardships and people who continue to have chronic stressors in their lives, like job and housing insecurity, and a lack of social support. That's what Galea and others have found in their research.

Mental health issues are emerging even in these early days of the war. Following the Oct. 7 Hamas massacre, Israel's mental health crisis line saw a surge in calls, says sociologist Nira Kaplansky, who oversees the hotline, which is run by an organization called Natal.

"From a line of 25 to 100 calls a day, we became a line of 1,200 calls a day," she says.

Almost overnight, she and her colleagues had to train more volunteers online to become crisis counselors. "We were around 50 volunteers and now we are 150," says Kaplansky.

Even as Hamas carried out the attacks, people called the NATAL helpline out of sheer desperation because they couldn't get through to the army or other helplines, she says.

"We had calls from people that were inside their panic rooms, and they were telling us that someone is trying to open the panic room and they are inside with their wife and kids," says Kaplansky.

"The only thing that you can do is stay there with" the caller, says Kaplansky, and reassure them they are doing the best thing to protect their family.

She also recounts a call from a young person "who was in a panic room and both his parents were dead in the room near him. [He was] asking, crying, screaming for help."

Those aren't the kind of calls Natal's crisis counselors were used to answering.

The work has been emotionally difficult for the staff and volunteers, too, she adds, because they have been reeling from their own trauma and grief.

"Each one of us has been to at least one funeral in the last week, sometimes two,"

"I have friends who have lost children and I have friends who have a kidnapped child," says Emi Palmor, the chair of NATAL. "And really, you say to yourself 'I don't want anything in my life anymore. Nothing. I just want to be out of this nightmare.'"

The call volume has decreased since the initial surge but remains above normal, says Kaplansky. People are calling to describe classic trauma-related symptoms: intrusive thoughts about the attacks, nightmares, not being able to sleep.

The callers say they are trying to avoid situations that remind them of what they went through. For example, "'I don't want to be where there's people around me and I don't know who they are,'" says Kaplansky, "'I don't want to be in an enclosed place. I can't hear explosions anymore."

Counselors tell the callers that these are all normal reactions to traumatic circumstances — and they may keep people from functioning in their daily lives. For people who need further mental health care, the counselors refer them to Natal's clinics.

Both Kaplansky and Palmor expect the need for mental health care to remain high for the foreseeable future.

"So if we are terrified [now], you can imagine what the morning after [might be]," says Palmor. "And we don't know when this morning after will arrive. We are still heading a conflict in Gaza, which can be awful and it's going to cost lives."

Continuous stress in Gaza

In Gaza, about 1.4 million people have left their homes and are trying to stay safe from Israel's airstrikes as they wait for aid.

Iman Farajallah is a Palestinian-American psychologist based in the Bay Area in California. She grew up in Gaza and is now anxiously eyeing her phone for any news from family members in the territory.

"All my siblings, all of their homes [have been] bombed, all of them," she says. "My sisters right now, they are staying in schools on the northwest coast. But they have no electricity, no access to electricity, water or food."

One of her brothers has been carrying their 85-year-old father on his back from shelter to shelter, she says. Lately, sometimes days pass before she receives any word from them because of limited electricity and internet access in Gaza.

"When I send them a message and it takes 2 to 3 days for them to get a little bit of internet to send me that 'we are okay,' 'we are still alive,' or, 'no, we are not okay, it's very touch," she says.

Farajallah has lost former neighbors and family members in Gaza in the past week, including children in her family. "My cousin lost his wife and three kids," she says. The children were at home with their mother, who had been "praying when they bombed her."

This war only adds to decades of violence and war experienced by people in Gaza, says Farajallah, who in recent years has documented the mental health impact of past conflicts on children there.

Children and adolescents in Gaza were already struggling with a range of mental health and behavioral symptoms.

"Cognitive symptoms such as confusion, lack of concentration, inattention, ADHD, incoherent speech, deterioration in their ability to achieve anything in a school," she says.

Many children have trouble complying with rules at home or at school, she adds. They also show symptoms of "social withdrawal or maybe anger and violence, wetting their bed, fear of darkness, generic tension, a flashback or nightmares."

Numerous past studies by other researchers have documented already high rates of mental health disorders like PTSD and depression in the population --especially among children and adolescents, who make up nearly half of the population in Gaza.

Estimates vary across studies, but a 2011 study by Lydia Dimitry of Imperial College London found that 23-70% of children and teens in Palestine had had PTSD.

Another study in 2011 by George Bonnano at Columbia University and his colleagues also found high rates of PTSD and depression in Gaza, the West Bank and East Jerusalem, and many people with these symptoms struggled to recover because of chronic exposure to violence as well as the chronic stress of personal losses and poverty.

Farajallah notes that the diagnosis of PTSD doesn't capture what people in Gaza struggle with.

"We cannot call this PTSD. It's a continuous trauma that is happening over and over and over again 24/7. Ninety-nine percent if not 100% of the population of Gaza, they all suffer from continuous trauma."

She worries that the current conflict just exacerbates prior traumas, creating "a traumatized nation."