Case reports of chronic traumatic encephalopathy (CTE) continue to emerge among retired NFL football players.
In a previous post, I have summarized a Mayo Clinic study finding limited evidence for increased brain injury in a cohort of high school football players.
In another related post, I summarized research demonstrating college football players with sport-related head trauma had evidence of disruption of the blood-brain barrier.
Recently, an additional post-mortem autopsy study of football players in the Canadian Football League (CFL) adds important information.
Hazrati and colleagues from the University of Toronto examined the brains of a convenience sample of six male adults who had a history of multiple concussions while playing in the CFL. Additionally, they required that each member of the series had documentation of symptoms of a brain disorder. These symptoms could include cognitive, motor or psychiatric symptoms. The clinical presentation and age of the cases were:
- Case 1: Memory impairment and apathy onset age 70
- Case 2: Emotional lability and slurred speech at age 56 later diagnosed with ALS
- Case 3: Personality changes and flat affect at age 50
- Case 4: Memory impairment and other cognitive deficits at age 55
- Case 5: Anger problems, impaired judgement and irritability at 64
- Case 6: Social withdrawal, anxiety and lethargy beginning at age 48
On neuropathological autopsy, the authors noted several findings of importance:
- Only three brains (cases 1,3 and 4) demonstrated changes diagnostic for CTE
- All three brains with CTE demonstrated a second brain pathology (Alzheimer's disease, diffuse Lewy body disease and multiple brain infarctions)
- Brains without CTE demonstrated other causes for brain disorder (ALS, Alzheimer's disease and Parkinson's disease)
This case series is important because it demonstrates that not all football players with a history of concussion show CTE changes in the brain. And in those that do demonstrate CTE, it appears other brain pathologies may contribute clinical symptoms of cognitive, psychiatric and motor decline.
The brain biopsy case series in this sample is biased toward those demonstrating evidence of brain disease. A better sample would be a randomized series CFL players with and without concussion histories independent of whether brain disease symptoms exist. Such samples might be enriched by comprehensive neuropsychiatric assessment/record review, genetic analysis (i.e. APOE gene status) and structured family interviews for family history of dementia and mental disorders.
These types of more comprehensive studies are expensive and take a long time to complete. Nevertheless, only with these types of study will be be able to fully understand the risk for brain disorders associated with playing football.
Readers with more interest in this topic can access the free full-text article by clicking on the PMID link below. Excellent brain pathology photos are included in the manuscript.
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Hazrati LN, Tartaglia MC, Diamandis P, Davis KD, Green RE, Wennberg R, Wong JC, Ezerins L, & Tator CH (2013). Absence of chronic traumatic encephalopathy in retired football players with multiple concussions and neurological symptomatology. Frontiers in human neuroscience, 7 PMID: 23745112