Too early to link tau proteins to dementia

Many scientific studies present initial data that can provide a promising basis for future experiments.  Unfortunately, those studies are often misrepresented in the popular press and falsely raise the hopes of affected individuals.

In a study published this week in the American Journal of Geriatric Psychiatry researchers performed PET scans on the brains of five former NFL players.  The results indicated that the tau protein, believed to be responsible for chronic traumatic encephalopathy (CTE), could be identified in living subjects.  Tau could previously only be identified by staining brains recovered at autopsy.

CTE was actually first described in 1928 based on studies of deceased boxers.  It was called “Dementia Pugilistica” or “Boxer’s Dementia.”  Modern staining techniques have identified the deposition of the tau protein in certain areas of the brains of athletes who have suffered repetitive brain trauma.

The clinical presentation of CTE consists of cognitive decline, personality changes and movement disorders.  Although there is a clear correlation between tau protein and CTE, not everyone who has tau protein also has the syndrome of CTE.

The current report gives the impression that the scan performed as part of the research can now identify patients who will develop dementia.  This is not true and very misleading.

“Tau can be a marker of the presence of disease but may not be a biomarker of disease activity. Placing too much emphasis on a marker of disease as a true biomarker without years of clinical disease correlation may lead to treating a finding without clinical relevance,” said Dr. Kevin Crutchfield, a neurologist and Director of the Comprehensive Sports Concussion Program at Sinai Hospital of Baltimore.

Another criticism of the proposed correlation is the fact that this study involved only five athletes. 

While many researchers and clinicians are hopeful that we will someday be able identify and treat all forms of dementia before they cause significant impairment, this is many years away.