Do some 9/11 responders have a new kind of dementia?

Eddie Reyes is comforted while remembering fifteen of his colleagues in the New York Police Department Emergency Service Unit who were killed on September 11, 2001 during a first responders wreath-laying ceremony at the National September 11 Memorial on September 20, 2011 in New York City. (Credit: Alex Wong/Getty Images)

New research suggests a specific form of dementia could be affecting September 11th responders who also have post-traumatic stress disorder.

The researchers found that World Trade Center responders with cognitive impairment (CI) and post-traumatic stress disorder (PTSD) have a different presentation of the white matter in their brains compared to responders with CI without PTSD.

Cognitive impairment is a possible sign of dementia.

The researchers assessed the brains of 99 World Trade Center (WTC) responders using diffusion tractography, a 3D imaging technique.

According to the authors of the study in the Journal of Alzheimer’s Disease, this is the first study to examine white matter alterations using connectometry in a sample of WTC responders in mid-life (average age: 56) with and without concurrent PTSD.

The goal of the study was to examine and elucidate the extent to which white matter tract integrity might be impaired in WTC responders with cognitive impairment (CI) and/or PTSD. Previously, the researchers had identified changes in white matter diffusivity in small numbers of responder patients.

“Our findings are by no means conclusive in terms of defining CI or dementia in WTC responders, and if this study provides evidence of a new form of dementia emerging,” says lead author Sean Clouston, an associate professor in the program in public health, and in the family, population, and preventive medicine department at Stony Brook University.

“Overall, the study supports the view that responders with CI have neurological changes consistent with neurodegenerative disease, but they are inconclusive as to the type of disease,” he adds. “Our findings do show that dementia due to PTSD is clearly different from non-PTSD dementia in this responder population.”

The researchers matched the subjects in the study by age, gender, occupation, race, and education. Cognitive status was determined by using the Montreal Cognitive Assessment, and PTSD status was determined by using the Diagnostics and Statistics Manual-IV. The researchers used diffusion tensor imaging via a mMR scanner, and they used connectometry to examine whole-brain tract level differences in white matter integrity as reflected by fractional anistrophy (FA) values.

In summary, the team found that FA was negatively correlated with CI and PTSD status in the fornix, cingulum, forceps minor of the corpus callosum, and the right uncinate fasciculus. Additionally, FA was negatively correlated with PTSD status, regardless of the CI status in the superior thalamic radiation and the cerebellum.

The authors conclude that the brain imaging results “suggest that WTC responders with early-onset CI may be experiencing an early neurodegenerative process characterized by decreased FA in white matter tracts.”

Clouston and colleagues used the imaging technique diffusion tractography to examine how healthy axons are in the brain’s white matter. The technique helped to determine that responders with CI had signatures in their white matter that did not match patterns seen in old-age Alzheimer’s disease and other related dementias.

By using the imaging technique, they also compared responders with PTSD and dementia to those with dementia but without PTSD. The imaging revealed a lot of similarities between the groups but also showed a remarkable difference in the white matter of those with PTSD and dementia—showing evidence of cerebellar atrophy, a finding that is inconsistent with other studies of dementia.

The National Institutes of Health’s National Institute on Aging, the Centers for Disease Control and Prevention, and the National Institute for Occupational Safety and Health funded the work.

Source: Stony Brook University