Brain structural changes linked to chronic PTSD in World Trade Center responders

New research among World Trade Center (WTC) responders with chronic post-traumatic stress disorder (PTSD) has uncovered measurable physical changes in their brain structure, consistent with changes in the balance of myelinated to unmyelinated neurons (fast- and slow-conducting nerve cells) across both hemispheres of the brain. These changes were most strongly associated with re-experiencing symptoms in individuals with PTSD. The cortical differences found in this sophisticated imaging study in Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, published by Elsevier, may serve as surrogate biomarkers for compromised brain health in people suffering from chronic PTSD, as well as potentially informing early screening strategies.

Following the collapse of the WTC, many people experienced severe trauma, and 23% of WTC responders developed PTSD. This is experienced, in part, as uncontrolled intrusive memories of the traumatic events linked to triggering events, coupled with elevated stress reactivity and hyper-awareness of surroundings.

Editor-in-Chief of Biological Psychiatry: Cognitive Neuroscience and Neuroimaging Cameron S. Carter, MD, University of California Irvine School of Medicine, comments, "While previous studies provide clues about the role of neurological changes in PTSD, to date, the importance of cortical microstructure and the role of cortical myelination have not been well understood."

This study used gray-white contrast (GWC) neuroimaging, an MRI-based technique poised to enhance studies of neuronal health for traumatized individuals. GWC acts as a proxy for intracortical myelination density, examining the apparent blurriness at the white matter and gray matter interface based on differences in signal intensity. An increase in contrast represents a sharper boundary, indicative of a healthy transition from gray matter to cerebral white matter. A less distinct border (low GWC) suggests an abnormal concentration of myelin (fatty insulating layer), pointing to a disruption in the brain's processing speed and consistency.

We were able to determine the direction and location of change by varying the depths where the signals were sampled. There are few things that can change the gray matter signal, so we believe this finding may reflect changes in the concentration of myelinated neurons in the gray matter. We then compared GWC to other measures of cortical health previously associated with WTC-related PTSD."

Sean A.P. Clouston, PhD, lead investigator, Professor in the Program in Public Health, and Department of Family, Population, and Preventive Medicine, Renaissance School of Medicine (RSOM),  Stony Brook University

Evaluating structural brain images for 99 WTC responders, researchers found evidence of widespread changes in GWC in the cortical gray matter across both hemispheres of the brain in people with PTSD. Reductions in GWC could imply there is more myelin content in these regions than is normal in trauma-exposed responders without PTSD. They also found that GWC could be combined with other markers of intracortical health to improve the ability to help to objectively identify WTC responders with PTSD.

There are currently no objective methods to validate whether a person reporting PTSD symptoms might have the disorder, nor whether it is one condition among multiple possible conditions. Symptoms can also vary between individuals. Measuring GWC contrast could help improve diagnosis, especially when combined with other diagnostic methods.

"Biological tests for PTSD have eluded researchers for many years, but our study illustrates that modern analytic methods may be starting to reveal brain signatures of this disorder," notes co-investigator Roman Kotov, PhD, Professor in the Department of Psychiatry and Behavioral Health in the RSOM.

Investigators were surprised to find widespread dysfunction across much of the brain. These results also have important implications for brain health in individuals with chronic PTSD, since interneurons facilitate coordinated thinking across symptoms. Individuals with interneuronal changes often experience changes to physical functioning that can lead to movement problems and disability.

Co-investigator Benjamin Luft, MD, Director of the World Trade Center Health and Wellness Program at Stony Brook Medicine and Professor in the Department of Medicine at the RSOM, concludes, "Our study, expanding on clues from other studies, shows that PTSD is linked to measurable physical changes in brain structure, offering biological evidence that trauma reshapes neural integrity. These findings point toward new approaches for diagnosis and treatment."