Advanced CTE Quadruples Dementia Risk in Landmark Boston University Study
Researchers at Boston University have published the most comprehensive study to date linking chronic traumatic encephalopathy (CTE) with significantly increased dementia risk. The findings indicate that individuals with the most advanced stages of CTE are 4.5 times more likely to develop dementia during their lifetime compared to those without the condition.
Clear Evidence Emerges from Brain Tissue Analysis
The Boston University CTE Center examined brain tissue from more than 600 donors, predominantly male contact sport athletes with known exposure to repetitive head impacts. Crucially, none of the donors had Alzheimer's disease, Lewy body disease, or frontotemporal lobar degeneration - three of the most common neurodegenerative diseases that cause dementia.
Among the 366 male donors found to have CTE, researchers calculated dementia risk probabilities across different stages of the condition. The study revealed that only the most severe CTE cases - stages III and IV - showed clear associations with dementia, cognitive impairment and functional decline.
Distinguishing Between CTE Stages and Symptoms
Dr Michael Alosco, associate professor of neurology and co-director of clinical research at the BU CTE Center, emphasised the importance of these findings. "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," he stated.
The research team discovered that lower stages of CTE (I and II) showed no association with dementia, cognitive impairment or functional decline. Furthermore, they found no link between less severe CTE and changes in mood or thinking, suggesting these symptoms may stem from other effects of repetitive head impacts or unrelated medical factors.
Misdiagnosis Challenges and Alzheimer's Confusion
The study uncovered significant diagnostic challenges, revealing that dementia caused by CTE is frequently misdiagnosed as Alzheimer's disease. Among donors with CTE who received dementia diagnoses during their lifetime, 40% were told they had Alzheimer's disease despite showing no evidence of the condition during autopsy.
An additional 38% of donors' families were informed that the causes of dementia were "unknown" or could not be specified. Both Alzheimer's and CTE involve abnormal tau protein buildup in the brain, though researchers note the tau differs between conditions.
Implications for Diagnosis and Treatment
Dr Richard Hodes, director of the National Institute of Health's National Institute on Aging, highlighted the study's significance. "Understanding which brain changes drive cognitive decline is essential," he said. "This study shows that only severe CTE has a clear link to dementia, which provides an important distinction for researchers, healthcare providers and families."
The research, funded by the National Institutes of Health, represents a crucial step toward accurate detection and diagnosis of CTE during life. While diagnosis currently remains possible only after death, these findings could eventually lead to improved diagnostic methods and targeted treatments for athletes and others exposed to repetitive head trauma.
Former NFL players including Junior Seau, Frank Gifford and Ken Stabler have been posthumously diagnosed with CTE, while former star quarterback Brett Favre has publicly wondered whether he might be affected. The condition has long been associated with professional athletes in contact sports, though researchers continue to investigate its precise causes and mechanisms.
