Home Trade school Can PET/MRI correlate tau with cognitive problems in first responders?

Can PET/MRI correlate tau with cognitive problems in first responders?


Researchers from the Renaissance School of Medicine in Stony Brook and Northwell Health in New York found very high levels of tau protein in several first responders during the World Trade Center terrorist attacks, but most subjects did not had not progressed to Alzheimer’s disease or dementia.

“Preliminary results from this pilot study show that most first responders have relatively high tau levels, but are not compatible with Alzheimer’s disease,” said June Zhou, a medical student at Stony Brook. “However, we have two subjects with very high tau levels [who are] without cognitive impairment. »

Search and rescue operations conducted after the collapse of the two World Trade Center towers on September 11, 2001 exposed emergency responders to extremely damaging emotional, mental and physical conditions, including exposure to toxic substances. Over the next few years, about 23% of this population developed chronic post-traumatic stress disorder (PTSD), four times more than about 6% of the general population.

PTSD, cognitive impairment

Previous studies involving these emergency workers have shown that the severity of their PTSD symptoms correlates with their degree of cognitive impairment. Other research has found evidence of unique neuropathology among people with cognitive impairment within this same group. Specifically, responders with cognitive impairment showed “reduced cortical thickness, compared to cognitively normal responders, as well as negatively affected brain regions in responders with PTSD,” Zhou told SNMMI participants.

“As responders approach their 40s, they also appear to have a higher incidence of cognitive impairment than the general population as well as in their same age group,” she said.

Since cognitive impairment is quite common in patients with Alzheimer’s disease and dementia, Zhou and his colleagues created a pilot study to use PET/MRI to assess the extent and location of deposition of tau, which have been linked to both conditions, in brain regions. which included the amygdala and the inferior temporal and lateral occipital lobes.

To date, researchers have recruited 14 responders (range, 50-61 years), of whom 11 (78%) have cognitive impairment and five (45%) have PTSD. Subjects are required to take the Montreal Cognitive Assessment Test (MoCA) to assess their cognitive abilities and are excluded from the study if they have conditions, such as a history of psychosis, that would skew cognitive assessments and results .

This was followed by PET/MRI examinations (Biograph mMR, Siemens Healthineers), which began 80 to 100 minutes after injection of the PET radiotracer F-18 flortaucipir (Tauvid, Avid Radiopharmaceuticals), which showed an ability to detect tau pathology. and to help differentiate between people with Alzheimer’s disease and mild cognitive impairment and healthy controls. The PET images were then recorded on MRI rapid acquisition gradient echo (MPRAGE) images prepared in T1 weighting. Standardized uptake values ​​(SUV) in brain regions were partially corrected and normalized using cerebellar gray matter.

Flortaucipir-PET images show tau deposits with substantial frontal and temporal uptake, relative to the cerebellar gray reference region (indicated by crosshairs). Image courtesy of SNMMI, June Zhou, and Stony Brook Renaissance School of Medicine.

Insufficient for diagnosis

While researchers found that nine responders (64%) met the criteria for preclinical Alzheimer’s disease, only three responders (21%) had reached stage I-II Alzheimer’s disease with abnormally high uptake in the entorhinal cortex. More interestingly, Zhou and colleagues noted in their abstract that only one respondent “had stage III compatible patterns [Alzheimer’s]and one had uptake in the temporal cortex consistent with advanced Alzheimer’s disease, although all regions thought to show stage IV tau increases were unaffected.

Considering the results obtained so far, Zhou and colleagues concluded that “tau status alone is not sufficient to diagnose Alzheimer’s disease and related dementias, even in the context of cognitive impairment.”

They added, however, that it is “concerning that these responders have increased tau signaling at ages when Alzheimer’s disease and related dementias are rare. In the responder with the greatest tau load, the distribution of proteins tau did not follow the expected pattern, suggesting a neuropathology that differs from patterns seen in conventional Alzheimer’s disease and related dementias.”

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