Brain scans of 9/11 World Trade Center responders conducted approximately two decades after the attacks reveal that highly resilient individuals show heightened activity in brain regions responsible for anticipating rewards. The findings point to potential new pathways for understanding and treating posttraumatic stress disorder.
How the brain responds to anticipated rewards may play an important role in psychological resilience after traumatic experiences, according to a new study of 9/11 World Trade Center responders. The findings, published in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, suggest that the brain’s ability to detect and respond to positive information may help buffer the effects of trauma exposure and point to potential new targets for treating posttraumatic stress disorder (PTSD). Thousands of workers involved in rescue, recovery, and cleanup efforts after the September 11, 2001, attacks experienced unprecedented trauma. Yet many of these individuals demonstrated remarkable psychological resilience despite their exposure to traumatic events. Reward processing is the brain’s system for recognizing positive experiences, motivating behavior, and helping us learn from outcomes that benefit us. These experiences can be either anticipated – such as a reminder of an upcoming positive outcome – or directly experienced. Psychological factors that rely on intact reward processing and anticipation, including the capacity for positive emotions, optimism, and hope, have long been associated with greater resilience to stress. However, the brain mechanisms underlying this relationship have rarely been studied.
Investigating Reward Circuitry Among World Trade Center Responders
Little is known about brain function during reward anticipation in resilient individuals,
said lead investigator Adriana Feder, MD, Professor of Psychiatry at the Icahn School of Medicine at Mount Sinai. “This study is unique in its focus on the function of reward circuitry in highly resilient individuals, compared with those with chronic PTSD and lower WTC-exposed controls. All participants were involved in rescue and recovery work following the 9/11 attacks on the WTC, but the severity of exposure varied.”
In the new study, researchers examined brain activity approximately two decades after 9/11, among rescue and recovery workers from the WTC Health Program General Responder Cohort. Participants included individuals with and without chronic WTC-related PTSD, as well as responders with varying levels of exposure to potentially traumatic elements of the 9/11 attacks and their aftermath. Researchers used functional magnetic resonance imaging (fMRI) to measure and map brain activity while participants completed a reward-based task with each trial including a reminder of whether their performance on the upcoming trial could result in winning or losing money.
We wanted to understand why some World Trade Center responders developed chronic posttraumatic stress disorder, while others maintained good psychological health despite experiencing similar extreme stressors during recovery efforts,
said co-lead investigator Robert H. Pietrzak, PhD, MPH, Professor of Psychiatry at Yale School of Medicine.
Most people recognize PTSD symptoms such as flashbacks, intrusive memories, and hypervigilance. However, PTSD can also diminish a person’s capacity to experience positive emotions, including happiness, enjoyment, and love.
Differences in Neural Activation Across Exposure and Symptom Groups
Researchers divided participants into three groups:
- Responders with chronic WTC-related PTSD
- Psychologically healthy trauma-exposed controls, including:
- A. Highly resilient responders: Individuals with substantial exposure to potentially traumatic elements of the 9/11 WTC attacks, such as finding human remains or being caught in the dust cloud
- B. Lower WTC-exposed responders: Individuals who had a lower level of exposure to potentially traumatic elements during their WTC recovery work
The highly resilient group showed the strongest increase in activity in brain regions involved in processing rewards. This included the nucleus accumbens, which is involved in detecting rewards, and the ventromedial prefrontal cortex, which helps the brain evaluate and weigh rewards.
Potential Implications for PTSD Treatment and Prevention
One intriguing hypothesis that warrants future investigation is whether this protective neural capacity may be a modifiable therapeutic target, i.e., whether we can ‘train the brain’ to better anticipate positive outcomes to prevent or treat PTSD, Dr. Feder noted
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