US researchers studied data on 77 hockey players who donated their brains after death and found that each additional year of hockey playing increased the risk of chronic traumatic encephalopathy and the level of phosphorylated tau protein in the brain. This is the first and largest study of the link between hockey playing and the development of the disease. The results are published in JAMA Network Open.
“Boxer’s dementia,” or chronic traumatic encephalopathy (CTE), is a neurodegenerative disease caused by repeated head injuries. Physiologically, it is characterized by excess accumulation of phosphorylated tau protein in the brain, similar to Alzheimer’s disease, and symptoms include cognitive impairment, depression, and suicidal behavior. CTE is common among boxers and American football players, with early research showing that the risk of developing the disease increases with each year of play. This may also be true for ice hockey, where players often suffer head injuries, but the connection has not been studied.
Scientists from the Boston University School of Medicine and other US institutions, led by Bobak Abdolmohammadi, analyzed data from 77 male hockey players who donated their brains to three brain banks after death. CTE was found in 42 of the 77 donors (54.5 percent), while 27 of the 28 professional players (96.4 percent) suffered from the disease.
The risk of developing the disease increased with the length of playing experience. Only 5 of 26 men who had played hockey for less than 13 years had CTE. And among donors who had played for more than 23 years, almost 96 percent — 23 out of 24 people — suffered from the pathology. Even after taking into account all other factors — age at death, playing other contact sports, age at which hockey began, the player’s position, and the number of concussions — each year of play increased the probability by 1.34 times. In addition, the load of phosphorylated tau protein in the brain increased with the length of play.
Most of the donors in the study committed suicide: ten people, or 38.5 percent, of those with CTE and ten donors, or 28.6 percent, of those without. A similar pattern was seen among American football players who suffered from the same condition.
The authors identified threshold values for playing time: 7.5 and 18 years. In general, men with less than 7.5 years of playing experience did not suffer from CTE, while those with more than 18 years did. However, the scientists noted that the sample was not representative, meaning that the detected CTE frequency cannot be considered the frequency of CTE in the population of male hockey players. In addition, in this study, as in studies with American football players, the main indicator was years of playing, which does not always directly correlate with the frequency of head injuries.
We talked about chronic traumatic encephalopathy in more detail in the article “Amazing Football”.
