Study reveals link between contact sports participation and parkinsonism in individuals with chronic traumatic encephalopathy
The largest study of CTE to date has found a new link between contact sports participation, chronic traumatic encephalopathy (CTE) and the development of a movement disorder known as parkinsonism.
The study of 481 deceased athletes by researchers from Boston University Chobanian and Avedisian School of Medicine and VA Boston Healthcare, published today in JAMA Neurologyit appears that most individuals with CTE developed parkinsonism, and CTE pathology appears to be the cause of the parkinsonism symptoms in most cases.
Parkinsonism is a condition characterized by symptoms similar to Parkinson’s disease, such as tremor, abnormal slowness of movement, or abnormal stiffness of the arms or legs. It has long been associated with traumatic brain injury (TBI) and CTE in boxers. However, the specific pathologies underlying these symptoms in CTE were unknown.
Parkinson’s disease is classically associated with the buildup of proteins called Lewy bodies in brain cells, but researchers found that 76% of individuals with CTE and Parkinsonism did not do Have Lewy body pathology.
“We were surprised to find that most individuals with CTE and parkinsonism did not have Lewy body pathology,” noted Thor Stein, MD, PhD, associate professor of pathology and laboratory medicine at BU and VA Boston Healthcare, and one of the study’s corresponding authors. “Instead,” Stein explained, “subjects with parkinsonism were more likely to have more severe CTE-related brain cell death in a region of the brainstem important for controlling movement.”
CTE is a degenerative brain disease whose only known cause is repeated head blows, such as those that occur in contact sports. A 2018 study by the same research team found that the duration of contact sports is associated with an increased risk of developing Lewy body disease. However, the current study is the first to describe a link between contact sports participation, brainstem pathology, and parkinsonism in CTE.
“Increased CTE severity has been shown to be associated with longer playing time,” noted Daniel Kirsch, an MD/PhD student at BU and one of the study’s first authors. “In this study, we found that eight additional years of contact sports play was associated with a 50 percent increased risk of more severe disease in a specific area of the brainstem that controls movement.”
The study subjects donated their brains to the Understanding Neurologic Injury and Traumatic Encephalopathy (UNITE) brain bank. People with parkinsonism were compared to those without to identify the types of pathologies that might explain why some people with CTE develop these symptoms and to examine relationships with the duration of contact sports.
This study underscores the importance of understanding the long-term effects of repeated head impacts and the need for preventive measures in contact sports to reduce the risk of neurodegenerative diseases such as CTE and parkinsonism.
