Acute trauma can trigger onset of obsessive-compulsive disorder, study shows

When survivors of the October 7th attacks returned to what was left of their homes, many carried with them more than grief or post-traumatic stress. A new study shows that the trauma also fueled an unexpected surge in obsessive-compulsive disorder, offering the first direct evidence that acute trauma can trigger the disorder's onset.

In the aftermath of the October 7th attacks in Israel, a team of psychologists and psychiatrists noticed an unsettling pattern among survivors: obsessions and compulsions that hadn't been there before or that have exaggerated. A new study, led by Prof. Eyal Kalanthroff of the Hebrew University of Jerusalem and Prof. Helen Blair Simpson of Columbia University alongside students Shir Berebbi and Mor David, provides the first direct evidence that acute trauma can spark the onset of obsessive-compulsive disorder (OCD) — or intensify existing symptoms.

The research, published this month, followed 132 adults, half of whom were survivors from communities in the Gaza envelope — towns and villages that endured the brunt of Hamas's assault. Four to six months later, nearly 40 percent of those directly exposed to the violence met the criteria for probable OCD, compared to just 7 percent of a matched control group elsewhere in Israel.

Among the survivors, nearly one in four reported new-onset OCD symptoms after the attacks,. Many others saw their pre-existing symptoms worsen. "This is the first time we've been able to show directly that acute trauma can also trigger obsessive-compulsive symptoms," said Prof. Kalanthroff, who worked closely with Berebbi and David on data collection and analysis, and with Simpson, a leading authority on OCD and trauma at Columbia University.

Trauma and compulsion

Psychologists have long suspected a connection between trauma and OCD, given the high overlap with post-traumatic stress disorder (PTSD). But until now, most of the evidence was indirect. The team's findings suggest that trauma severe enough to induce PTSD may also set the stage for OCD, with PTSD symptom severity partially explaining the rise in compulsive behaviors.

The findings support the "diathesis-stress" model of mental illness, in which genetic vulnerabilities interact with overwhelming stress to produce psychiatric disorders. In some cases, exposure to extreme, life-threatening violence was sufficient to trigger symptoms that had not previously been present.

The human toll

The survivors from communities in the Gaza envelope had been displaced for months when they completed the surveys.

The most common new symptom was compulsive checking, often tied to fears of invasion or safety. Survivors described repeatedly verifying locks, windows, and doors — behaviors that offered a fragile sense of control in an environment where control had been violently stripped away. However, various other symptoms were also evident, ranging from compulsive cleaning to ordering.

Implications for treatment

The study was carried out with the support of the Hebrew University and the Molberger Scholar Award at Columbia University (that supports a scholar to work with Dr. Simpson), drawing on both local fieldwork and clinical expertise. The researchers caution that their findings, while striking, are limited by reliance on self-reported symptoms rather than clinical interviews. Still, the data suggest an urgent need for health systems to screen trauma survivors not just for PTSD and depression, but also for OCD.

"Treatment for trauma-related disorders needs to be more holistic," said Prof. Simpson. "Clinicians should consider OCD symptoms alongside post-traumatic stress, because missing them means leaving people untreated for a condition that can deeply affect their lives."

The study highlights the hidden psychological costs of conflict, which may reverberate across generations. Beyond the destruction of homes and families, war alters mental processes in ways that are only beginning to be understood.