To date, the progressive brain disease associated with repeated head impacts and found in athletes, military personnel, and victims of physical abuse, is diagnosed only after death.
"Cognitively symptomatic male brain donors with autopsy-confirmed CTE had more severe visually rated frontal, temporal, and hippocampal atrophy and increased odds for having a CSP (cavum septum pellucidum) on antemortem MRI scans compared to same-age men with NC (normal cognition). In addition, more severe p-tau pathology was associated with greater MRI ratings of atrophy," Dr. Jesse Mez of Boston University and colleagues write in Alzheimer's Research & Therapy.
"If validated with prospective clinical-pathological correlation studies, these findings support the use of structural MRI as a valuable tool to support a diagnosis of CTE during life," the authors add.
Dr. Alosco and his colleagues characterized macrostructural MRI features of brains with CTE, and they assessed the link between hyperphosphorylated tau (p-tau) and atrophy on MRI.
They analyzed antemortem MRI scans from 55 deceased symptomatic men over 60 years of age with CTE and compared them with scans from 31 men (11 deceased) with normal cognition at the time of the scan. They visually rated the presence of regional atrophy and microvascular disease from 0 (none) to 4 (severe), microbleeds, cavum septum pellucidum, as well as tau severity and atrophy at autopsy according to semi-quantitative scales.
Compared with brains of unimpaired males, brains with CTE (45 of 55 with stage III/IV) showed significantly greater atrophy of the orbital-frontal (mean difference, 1.29), dorsolateral frontal (mean difference, 1.31), superior frontal (mean difference, 1.05), anterior temporal (mean difference, 1.57), and medial temporal lobes (mean difference, 1.60). Brains with CTE also had larger lateral ventricles (mean difference, 1.72) and third ventricles (mean difference, 0.80).
Brains with CTE had higher odds of a cavum septum pellucidum (odds ratio, 6.7; P<0.05). Among brains with CTE, greater tau severity in 14 regions was linked with greater atrophy on MRI (beta, 0.68; P<0.01).
The researchers found no effects for posterior atrophy or microvascular disease.
"Our findings are not ready for the clinic, but they show we are making rapid progress," Dr. Mez told Reuters Health by email.
Two experts who were not involved in the study also welcomed its findings.
Dr. Jamie L. Bradbury, an assistant professor of clinical neurological surgery at the Indiana University School of Medicine in Indianapolis, said, "This study is a key addition to the literature to help the medical community better understand important characteristics found on MRI for patients with CTE."
"This brings us closer to providing a diagnosis in a living patient with dementia," he told Reuters Health by email.
"The main weakness of the study, as mentioned by the authors, is that the MRI findings are not in comparison to other patients with dementia," Dr. Bradbury added.
"We need to know how to differentiate CTE from other forms of dementia," he noted. "However, first defining the abnormalities in comparison to a normal population is a key step."
Dr. Hans C. Breiter, a professor of psychiatry and behavioral sciences at the Northwestern University Feinberg Shool of Medicine, in Chicago, and the co-director of the Concussion Neuroimaging Consortium, told Reuters Health by email. "The study is timely in that it starts the important process of linking one measure that cannot be extended to clinical practice (i.e., postmortem sampling) with other measures that can be extended to clinical practice (i.e., MRI and behavioral assessments)."
"The finding of a significant set of relationships between these modalities is extremely critical and lays the foundation for further work assessing early signs of CTE," he added. "One of the next steps needs to be longitudinal assessment of the appearance of these MRI markers to see how predictive early MRI signs are of future CTE."
SOURCE: https://bit.ly/3F4G8UL Alzheimer's Research & Therapy, online December 7, 2021.
By Lorraine L. Janeczko
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