• Posted February 20, 2026

Study Links Advanced CTE From Head Trauma as Distinct Cause of Dementia

For years, families of athletes and military veterans have watched loved ones slip into memory loss, suspecting the culprit was a lifetime of blows to the head.

Now, a major study from the Boston University CTE Center provides the data to back those suspicions: Advanced chronic traumatic encephalopathy (CTE), or stage IV CTE, quadrupled a person’s odds of dementia, the study found.

And being diagnosed with stage III CTE, the second-most severe stage, made a person twice as likely to have dementia symptoms.

CTE is a disease found in brain tissue. It includes a build-up of an abnormal protein called tau in a pattern that looks different from Alzheimer's disease. The changes in the brain might start months, years or even decades after the last head trauma.  

The findings, published recently in Alzheimer’s & Dementia, suggest that CTE isn't just a side effect of head trauma. It’s likely a distinct and devastating cause of dementia. 

Analysis of 614 brain donations from individuals exposed to repetitive head impacts revealed that the relationship between advanced CTE and dementia is just as strong as the link between dementia and advanced Alzheimer’s disease.

Researchers also noted how often CTE-related dementia is not diagnosed — or is misdiagnosed and treated as Alzheimer’s disease.

Today, CTE can only be confirmed after death by examining brain tissue. Because the symptoms — confusion, memory loss and personality changes — look so much like other conditions, many people are treated for the wrong disease.

Among brain donors who were diagnosed with dementia during their lives, 40% had been told they had Alzheimer’s disease. But autopsies later revealed they had no signs of Alzheimer’s at all and instead, CTE.

“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,” said study co-author Michael Alosco, an associate professor of neurology at Boston University, said in a news release.

The study also quiets claims from some sports-affiliated medical groups that CTE lacks clear clinical symptoms. The data showed that while low-stage CTE might not always cause noticeable impairment, the advanced stages are undeniably linked to trouble performing daily tasks like managing finances or driving.

“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,” Alosco said. 

He emphasized that the evidence shows CTE has a significant impact on lives, requiring stepped up efforts to distinguish it from other forms of neurodegeneration.

More information

The Mayo Clinic has more on CTE.

SOURCES: Boston University CTE Center, news release, Jan. 27, 2026; Alzheimer’s & Dementia, Jan. 27, 2026