Using PET imaging of brain tau in retired American football players, scientists have been able for the first time to see the brain damage caused by contact-sport head injuries.
This is an important first step toward early detection and intervention in people with trauma-related neurodegeneration.
Mild traumatic brain injury due to contact sports may cause chronic behavioural, mood and cognitive disturbances linked with pathological deposition of tau proteins. The accumulation of tau in the brain has been found to cause chronic traumatic encephalopathy (CTE), a degenerative condition linked with confusion, memory loss, progressive dementia, suicidal behaviour and tremors. However, until now, researchers were only able to confirm the presence of tau proteins at autopsy. Previous studies have shown that National Football League (NFL) players with three or more reported concussions were three times more likely to be diagnosed with depression and five times more likely to be diagnosed with mild cognitive impairment (MCI).
To examine whether brain tau deposits can be detected in living retired NFL players, a team of researchers at the University of California used PET scans with FDDNP, a new chemical tracer that binds to tau and amyloid in the brain. The participants underwent neuropsychiatric evaluations with the Hamilton Rating Scale for Depression and the Mini-Mental State Examination (MMSE) and were subject to FDDNP-PET.
The investigators, led by Dr Gary Small, found that tau protein deposits were higher in all subcortical regions and the amygdala (the areas that produce tau after trauma) in a group of five retired NFL players (aged 45-73) compared with controls. The NFL players had a history of one or more concussions and mood or cognitive symptoms. The results revealed that the football players had more depressive symptoms than the controls and generally had lower MMSE scores, which is indicative of cognitive decline. Three players had MCI, one had dementia and one was cognitively normal.
The study results were published last month in the American Journal of Geriatric Psychiatry.