New research suggests that a specific form of dementia may affect 9/11 responders who also have PTSD.

The researchers found that World Trade Center respondents with cognitive impairment (CI) and post-traumatic stress disorder (PTSD) had different white matter representations in their brains compared to CI respondents without PTSD.

Cognitive impairment is a possible sign of dementia.

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

According to the authors of the study in Journal of Alzheimer’s Diseasethis is the first study to examine white matter changes using connectometry in a midlife sample of WTC respondents (mean age: 56) with and without comorbid PTSD.

The purpose of the study was to investigate and elucidate the extent to which white matter tract integrity may be impaired in WTC responders with cognitive impairment (CI) and/or PTSD. The researchers previously identified changes in white matter diffusion in a small number of responders.

“Our findings are by no means conclusive regarding the definition of CI or dementia in WTC respondersand if this study provides evidence for the emergence of a new form of dementia,” said lead author Sean Clouston, associate professor in the Public Health Program and in the Division of Family, Population and Preventive Medicine at Stony Brook University.

“Overall, the study supports the view that responders with CI have neurological changes consistent with neurodegenerative disease, but they are not definitive about the type of disease,” he adds. “Our findings show that dementia due to PTSD is distinctly different from dementia without PTSD in this population of responders.”

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

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

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

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

Using the imaging technique, they also compared respondents with PTSD and dementia to those with dementia but no PTSD. The image revealed many similarities between the groups, but also showed a striking difference in the white matter of those with PTSD and dementia — showing evidence of cerebellar atrophy, a finding inconsistent with other dementia studies.

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

source: Stony Brook University

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