Research shows that nearly 25% of brain donors with chronic traumatic encephalopathy (CTE) linked to contact sports exhibited parkinsonism, indicating notable associations with substantia nigra (SN) pathology.
A recent study, published in JAMA Neurology, examined the correlation between SN pathology and parkinsonism in patients with CTE associated with contact sports. The researchers investigated neuropathologic features in brain donors diagnosed with CTE and their link to repetitive head impacts from contact sports.
In this cross-sectional study, 481 male brain donors with neuropathologically confirmed CTE were analyzed. The study found that parkinsonism was present in 24.7% of these donors. Neuropathologic markers associated with parkinsonism included SN Lewy bodies, neurofibrillary tangles, dopaminergic neuronal loss, and age at death. These results suggest that multiple abnormal protein accumulations and neuronal loss are linked to parkinsonism in patients with CTE in an age-dependent manner.
Patients with parkinsonism had a higher mean age at death (71.5 years) compared to those without parkinsonism (54.1 years), and also exhibited higher rates of dementia (87.4% vs 29.0%), visual hallucinations (37.8% vs 14.1%), and probable rapid eye movement sleep behavior disorder (43.7% vs 16.0%). Furthermore, patients with parkinsonism demonstrated more severe CTE pathology and greater SN involvement. Specifically, 29.4% of patients with parkinsonism had stage IV CTE compared to 10.8% of those without parkinsonism. Additionally, increased SN pathology was noted, including Lewy bodies (24.1% vs. 5.8%), neurofibrillary tangles (42.7% vs. 29.9%), and neuronal loss (52.1% vs. 17.1%).
The study identified an association between years of contact sports participation and increased SN neurofibrillary tangles (adjusted odds ratio [AOR], 1.04) and neuronal loss (AOR, 1.05), which were subsequently linked to parkinsonism.
The study authors concluded, "Repetitive head impacts may incite neuropathologic processes that lead to symptoms of parkinsonism in individuals with CTE."
Full disclosures can be found in the published study.
