Playing contact sports could raise risk of Parkinson’s-like movement disorder

• Playing contact sports is linked to the development of chronic traumatic encephalopathy (CTE), a brain disorder often caused by repeated head injuries.
• A new study found that athletes who developed CTE from playing contact sports have a high risk of Parkinsonism, a movement disorder similar to Parkinson’s disease.
• Some people with Parkinsonism may develop Parkinson’s disease later in life.

There is a strong link between playing contact sports and developing a movement disorder known as Parkinsonism, according to a large new study.

The link is chronic traumatic encephalopathy , or CTE, which results from repeated impacts to the head and concussions.

Parkinsonism is a term for a movement disorder similar to Parkinson’s disease . Symptoms include balance issues , stiffness in the arms or legs, and slow movement.

The researchers observed that the brains of people who had Parkinsonism were more likely to contain Lewy bodies in the Substantia nigra — an area of the brain involved in the control of movement — neurofibrillary tangles , a loss of neurons, and an earlier death. These are findings that are also found in Alzheimer’s disease and dementia.

The findings suggest that for every eight years of participating in contact sports, there is a 50% increase in the risk of further damage to the area of the brain controlling movement.

The researchers examined the brains, post-mortem, of 481 donors. Of these, 119 individuals had Parkinsonism. Those with more severe CTE were the most likely to develop Parkinsonism. In the study, 24.7% of people who had CTE also had Parkinsonism.

The study is published in JAMA Neurology .

Is Parkinsonism the same as Parkinson’s disease?

While Parkinson’s disease is considered a type of Parkinsonism, it is not the only kind.

Dementia with lewy bodies (DLB), Multiple system atrophy (MSA), Progressive supranuclear palsy (PSP), and Corticobasal degeneration (CBD) are all forms of Parkinsonism .

“Parkinsonism is typically progressive over many years and will often, though not always, develop into full-blown Parkinson’s disease,” corresponding study author Thor D. Stein, MD, PhD , associate professor of Pathology and Medicine at Boston University’s Chobanian and Avedisian School of Medicine in Boston, MA, told Medical News Today .

Daniel Truong, MD , neurologist and medical director of the Truong Neuroscience Institute at MemorialCare Orange Coast Medical Center in Fountain Valley, CA, not involved in the study, further explained the pathology of Parkinsonism.

“The rate of progression can vary significantly between individuals,” Truong told MNT . “Symptoms typically start subtly and gradually become more severe.”

Early indications may include slight tremors , stiffness, and slowed movements that can become more pronounced as years pass. These symptoms may eventually result in significant difficulties with movement and coordination.

“The progression can span over a decade or more, and advanced stages often involve severe mobility issues and cognitive decline,” Truong said.

How do head injuries cause CTE?

Stein explained how CTE develops. “As the brain moves inside the skull after a head impact, nerve fibers in the brainstem are likely stretched and damaged,” he said.

“Repeated head impacts may cause this damage to build up and result in CTE pathology within the brainstem,” Stein added.

CTE-producing injuries, said Truong, “often occur in sports such as American football, boxing, soccer, ice hockey, and rugby, where athletes frequently experience concussive and subconcussive blows to the head.”

CTE diagnosis can be challenging since no single test exists for the condition.

Study co-author Chris Nowinski, PhD , CEO of the Concussion Legacy Foundation, told MNT the only way to diagnose CTE is through an examination of the brain after death.

“Right now, we cannot calculate any athlete’s absolute risk due to the limitations of CTE being a post-mortem diagnosis,” Nowinski said. However, he noted, “at Boston University, more cases of CTE have been diagnosed among American football players than all other sports combined.”

“After football, CTE has been most frequently diagnosed among athletes who were boxers or played ice hockey, soccer, and rugby,” Nowinski said.

People who sustain concussions while serving in the military may also develop CTE.

“The cumulative effect of these repeated head impacts, rather than isolated incidents, significantly increases the risk of developing CTE,” Truong said.

“ Some research suggests that the highest magnitude head acceleration events drive CTE risk far more than repetitive smaller impacts. A single head impact of 100 Gs [gravity units] likely contributes far more than 100 Gs spread out over five impacts. A recent study by our team — as well as laboratory models — suggests that rotational acceleration contributes more to CTE risk than linear acceleration, and cumulative load correlates with CTE outcomes.”

— Chris Nowinski, PhD, study co-author

Early warning signs of of CTE

Truong explained that CTE is often characterized by cognitive decline and neurobehavioral dysregulation. Here are a few warning signs of CTE to look out for:

• Cognitive impairment — may manifest as memory problems , executive dysfunction, and difficulty with concentration and attention.
• Mood and behavioral changes — i.e., increased aggression, depression, anxiety, and impulsivity.
• Early signs of motor dysfunction — subtle changes in gait or balance and fine motor skill control.
• Issues with sleep — probable rapid eye movement sleep behavior disorder (pRBD) may be present.

“We encourage anyone with [CTE] symptoms to be seen by an expert,” Nowinski said.