Brain’s Reward Response Linked to Resilience in 9/11 Responders, Study Finds

A new study of responders to the Sept. 11, 2001 attack on the World Trade Center (WTC) has found that how the brain responds to anticipated rewards plays a key role in psychological resilience after trauma. The findings, published in the journal Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, come from Yale School of Medicine and the Icahn School of Medicine at Mount Sinai.

Thousands of WTC responders showed resilience despite extreme trauma, while others developed chronic PTSD. “We wanted to understand why,” says co-lead investigator Robert H. Pietrzak, a professor of psychiatry at Yale School of Medicine. He notes that beyond symptoms like flashbacks and hypervigilance, PTSD can also diminish a person’s capacity to experience positive emotions such as happiness, enjoyment and love.

Reward processing — positive emotion, optimism, hope — has long been linked to stress resilience, but the brain mechanisms behind it were rarely studied. About two decades after 9/11, researchers used functional MRI (fMRI) to scan WTC Health Program General Responder Cohort participants during a reward-based task. Participants fell into three groups: responders with chronic WTC-related PTSD, highly resilient responders who had substantial trauma exposure, and psychologically healthy responders with lower exposure.

The highly resilient group showed the strongest increase in activation in two reward-related brain regions: the nucleus accumbens, which helps detect rewards, and the ventromedial prefrontal cortex, which helps weigh them. This increase was significantly greater than in either the PTSD group or the lower-exposed group. Postdoctoral researcher Saren Seeley said self-reported measures of positive emotion distinguished only between responders with and without PTSD — the brain-imaging data captured something self-reports missed among resilient responders.

Co-lead investigator M. Mercedes Perez-Rodriguez, a professor of psychiatry at the Icahn School of Medicine at Mount Sinai, said one hypothesis for future research is whether this reward-related brain capacity may be a modifiable therapeutic target — training the brain to better anticipate positive outcomes to prevent or treat PTSD.