BU CTE Center researchers say their findings mean the progressive brain disease CTE should be recognized as a new cause of dementia. Photo via iStock/fstop123

CTE and Dementia

CTE Can Cause Dementia, According to New Boston University Study

BU CTE Center researchers found advanced stage of the progressive brain disease increases odds of dementia fourfold

A major new study from Boston University has found people with advanced chronic traumatic encephalopathy (CTE) have four times higher odds of getting dementia than those without the progressive brain disease. 

According to BU CTE Center researchers, the findings mean the disease should be recognized as a new cause of dementia; they also say their work counters recent contentious claims that CTE has no clinical symptoms.

The study is reportedly the largest of its kind.

“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,” says Michael Alosco, a BU Chobanian & Avedisian School of Medicine associate professor of neurology and codirector of clinical research at the CTE Center. “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.”

At the moment, CTE can only be diagnosed postmortem. Previous BU research has attributed the cause of the neurodegenerative disease, in part, to repeated hits to the head, including from collision-heavy contact sports like tackle football and ice hockey, military service, and domestic violence. CTE, which has four stages of severity, has been linked with a range of symptoms, especially problems with thinking or memory.

The new study, published in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association, looked at 614 brains from donors who had been exposed to repetitive head impacts, primarily contact sport athletes. By comparing 366 brain donors who only had CTE, but no other progressive brain disease, to 248 donors without CTE, researchers found those with the most advanced form of CTE were four times more likely to have dementia. Those odds are similar to those between dementia and advanced Alzheimer’s disease. The study did not find associations with low-stage CTE and dementia or cognition impairment.

Dementia is a clinical syndrome that refers to overall impairments in thinking and memory—caused by underlying brain diseases—that lead to trouble with performing everyday tasks like driving and managing finances. Alzheimer’s disease is the leading cause of dementia, but there are several other progressive brain diseases listed as causes that are collectively referred to as Alzheimer’s disease related dementias (ADRD). With this new study, Alosco and his colleagues say CTE should now also be formally considered an ADRD.

CTE Is Not a Benign Brain Disease

The latest study also reveals that dementia due to CTE is often misdiagnosed during life as Alzheimer’s disease, or not diagnosed at all. Among those in the study 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 at autopsy.

Sharing their findings, the researchers countered the controversial viewpoint expressed by some that CTE has no clinical symptoms. In 2022, clinicians and researchers affiliated with the Concussion in Sport Group meeting—which was underwritten by international professional sports organizations—claimed in a statement that it’s unknown if CTE “causes specific neurological or psychiatric problems.”

Previous BU research has charted the disease’s impact on the brain, from degenerated tissue to abnormal protein buildup. It’s also found a number of connections between repetitive head impacts and other neurological disorders, including a movement disorder similar to Parkinson’s disease.

“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,” says 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.”

This 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.

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