CTE should be recognized as new cause of dementia, study suggests

The largest study of its kind from the Boston University CTE Center reveals that chronic traumatic encephalopathy (CTE) should be recognized as a new cause of dementia.

The research, published online today in Alzheimer's & Dementia: The Journal of the Alzheimer's Association, studied 614 brain donors that had been exposed to repetitive head impacts, primarily contact sport athletes. By isolating 366 brain donors that had CTE alone, meaning they had CTE in the absence of any other progressive brain disease, compared to 248 donors without CTE, researchers found those with the most advanced form of CTE had a four times increased odds for having dementia. The four times odds are similar to the strength of the relationship between dementia and advanced Alzheimer's disease pathology, which is the leading cause of dementia.

This study provides evidence of a robust association between CTE and dementia as well as cognitive symptoms, supporting our suspicions of CTE being a possible cause of dementia. Establishing that cognitive symptoms and dementia are outcomes of CTE moves us closer to being able to accurately detect and diagnose CTE during life, which is urgently needed."

Michael Alosco, PhD, corresponding and senior author, associate professor neurology at Boston University Chobanian & Avedisian School of Medicine and co-director of clinical research, BU CTE Center

Dementia is a clinical syndrome that refers to impairments in thinking and memory in addition to trouble with performing tasks of daily living like driving and managing finances. Alzheimer's disease is the leading cause but there are several other progressive brain diseases listed as causes of dementia that are collectively referred to as Alzheimer's disease related dementias (ADRD). With this new study, the authors argue that CTE should now also be formally considered an ADRD.

The study also reveals that dementia due to CTE is often misdiagnosed during life as Alzheimer's disease, or not diagnosed at all. Among those who received a dementia diagnosis during life from a healthcare provider, 40 percent were told they had Alzheimer's disease despite showing no evidence of Alzheimer's disease at autopsy. An additional 38% were told the causes of their loved one's dementia was "unknown" or could not be specified.

In addition, this study addressed the controversial viewpoint expressed by some clinicians and researchers that CTE has no clinical symptoms. As recently as 2022, clinicians and researchers affiliated with the Concussion in Sport Group meeting, which was underwritten by international professional sports organizations, claimed, "It is not known whether CTE causes specific neurological or psychiatric problems."

"There is a viewpoint out there that CTE is a benign brain disease; this is the opposite of the experience of most patients and families," said Alosco. "Evidence from this study shows CTE has a significant impact on people's lives, and now we need to accelerate efforts to distinguish CTE from Alzheimer's disease and other causes of dementia during life."

As expected, the study did not find associations with dementia or cognition for low-stage CTE.

The authors note that prospective studies with objective assessments and age-matched controls are needed to validate their findings.

The study was supported by the National Institute of Neurological Disorders and Stroke, National Institute on Aging, Department of Veterans Affairs, and the Nick and Lynn Buoniconti Foundation.