Researchers identify potential new subtype of chronic traumatic encephalopathy

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease defined by abnormal tau protein accumulating in a particular pattern in specific regions of the brain.

Studies to date suggest CTE begins in the outermost layer of the frontal lobe, the neocortex, where it then spreads to connected brain regions. Later, in high-stage disease, there is involvement of deeper regions of the brain, like the medial temporal lobe and brainstem, and typically significant neocortical disease.

In a new study from the BU CTE Center, researchers found one in six individuals with high-stage CTE had surprisingly low levels of tau pathology in their neocortex. This newly identified form of CTE, called cortical-sparing CTE (CSCTE), instead showed a higher concentration of tau pathology in the individuals' medial temporal lobe and brainstem regions.

"This pattern of tau pathology suggests that CSCTE may be a distinct subtype of CTE with a different underlying biology," explained first author Abigail Alexander, MD, MPH, who performed the research while a resident affiliated with the Warren Alpert Medical School at Brown University.

"Furthermore, individuals with CSCTE were less likely to have dementia and had less severe cognitive impairment compared to those with typical CTE. However, they did tend to have earlier onset of behavioral and movement symptoms."

Brains from the Understanding Neurologic Injury and Traumatic Encephalopathy (UNITE) study underwent neuropathological assessment for CTE while online surveys and telephone interviews with next of kin, along with a review of clinical records were used to collect retrospective clinical information.

The researchers believe that further studies are needed to confirm the existence of CSCTE and to understand its clinical implications. However, they note that this finding could have important implications for the diagnosis and treatment of CTE.

"If CSCTE is confirmed to be a distinct subtype of CTE, it may be necessary to develop new diagnostic tools and treatment approaches that are specifically tailored to this form of the disease," added corresponding author Thor Stein, MD, Ph.D., a neuropathologist at VA Boston and Bedford Healthcare Systems and associate professor of pathology & laboratory medicine at Boston University Chobanian & Avedisian School of Medicine.

"This could help us understand why people with CTE can have different symptoms and ultimately lead to improved outcomes."

The work is published in the journal Acta Neuropathologica.