How Trauma Can Change Your Brain

New research suggests that trauma exposure can lead to significant changes in the brain, making individuals more likely to overreact to harmless facial expressions years later, even among those without a stress-related disorder. It seems that being near high-intensity traumatic events can have enduring effects on the brain and behavior of otherwise healthy individuals, without resulting in an immediate clinical disorder. However, these subtle alterations may heighten the risk of developing mental health issues in the future.

Research conducted by lead author Barbara Ganzel, PhD, and her team has shown that trauma can have lasting effects on the brains of otherwise healthy individuals. This was evidenced by assessing adults’ responses to emotional stimuli several years after they experienced a traumatic event. In the study, 22 healthy adults were exposed to both fearful and calm faces while undergoing functional magnetic resonance imaging (fMRI). This allowed researchers to measure the activity in their bilateral amygdala—the brain region responsible for assessing emotional intensity and for forming and storing emotional memories—between 3.5 and 4 years after the events of September 11, 2001.

All participants had varying degrees of exposure to the events of September 11. The authors aimed to investigate whether being in close proximity to a traumatic event, such as September 11, heightened sensitivity in certain brain areas to emotional stimuli 41 and 48 months post-attacks. Eleven participants were located within 1.5 miles of the World Trade Center on September 11, 2001, while the remaining eleven participants lived at least 200 miles away, serving as the control group. The control group, consisting of those who resided at least 200 miles from New York on 9/11/01, later relocated to the New York metropolitan area by the time the MRI scans were conducted.

According to the study, individuals who were located within 1.5 miles of the World Trade Center on 9/11 exhibited notably increased bilateral amygdala activity in response to fearful faces compared to those residing more than 200 miles away. These findings indicate that past exposure to traumatic events is linked to emotional responses years later in those who were near the original trauma. Yet, the participants did not meet the criteria for a diagnosis of PTSD, depression or anxiety at time of imaging. All the participants were screened for psychiatric, medical and neurological illnesses.

This research suggests that heightened reactivity in the amygdala following exposure to high-intensity trauma may take time to recover, potentially leading to intensified responses to everyday emotional triggers, according to the authors. Additionally, individuals located closest to the World Trade Center during 9/11 reported more current symptoms and a greater number of symptoms at the time of the trauma compared to those further away. These symptoms encompassed increased arousal (such as difficulty sleeping, irritability, and hypervigilance), avoidance behaviors (like a reluctance to visit downtown areas they once enjoyed), and intrusive experiences (including recurrent and distressing memories or dreams). Moreover, those who identified 9/11 as their most significant and intense trauma throughout their lives exhibited greater brain activity when viewing fearful faces.

“Our research indicates that trauma exposure may have lasting neurobiological effects, even in individuals who seem resilient. Since we observed these effects using mild, standardized emotional stimuli (rather than specific trauma reminders), they could influence daily life more than we previously realized,” explained Dr. Ganzel. “It has long been established that experiencing trauma can increase the risk of mental health disorders years later. This study provides insights into the biological factors contributing to that vulnerability. Understanding these processes will enhance our ability to offer assistance.”