November 7, 2019
In the general population, moderate exercise, physical activity, and participation in sports have important health benefits, including slowing cognitive decline and preventing dementia.1 Participation in elite-level sports, not surprisingly, is also associated with reductions in all-cause mortality and the risk of cardiovascular disease [Swedish: kardiovaskulära sjukdomar = hjärt- och kärlsjukdomar] . In recent years, however, there has been evidence that participation in some contact and collision sports may increase the risk of cognitive and neuropsychiatric impairment later in life,2 as well as the risk of neurodegenerative disease [Swedish: Neurodegenerativa sjukdom: sjukdom som långsamt förtvinar nervsystemet t.ex. demenssjukdomar] and chronic traumatic encephalopathy (CTE) ,3 [Swedish: se härunder]] because of repetitive brain trauma. It appears that it is not just the “big hits” resulting in symptomatic concussions that increase the risk of neurologic disorders later in life. Rather, the total duration of exposure to repetitive head impacts, including “subconcussive” injuries without symptoms, has been associated with neuropathology,4 in vivo markers of neurodegeneration,5 and cognitive and neuropsychiatric symptoms later in life.2
N Engl J Med 2019; 381:1862-1863
DOI: 10.1056/NEJMe1912071
In the general population, moderate exercise, physical activity, and participation in sports have important health benefits, including slowing cognitive decline and preventing dementia.1 Participation in elite-level sports, not surprisingly, is also associated with reductions in all-cause mortality and the risk of cardiovascular disease [Swedish: kardiovaskulära sjukdomar = hjärt- och kärlsjukdomar] . In recent years, however, there has been evidence that participation in some contact and collision sports may increase the risk of cognitive and neuropsychiatric impairment later in life,2 as well as the risk of neurodegenerative disease [Swedish: Neurodegenerativa sjukdom: sjukdom som långsamt förtvinar nervsystemet t.ex. demenssjukdomar] and chronic traumatic encephalopathy (CTE) ,3 [Swedish: se härunder]] because of repetitive brain trauma. It appears that it is not just the “big hits” resulting in symptomatic concussions that increase the risk of neurologic disorders later in life. Rather, the total duration of exposure to repetitive head impacts, including “subconcussive” injuries without symptoms, has been associated with neuropathology,4 in vivo markers of neurodegeneration,5 and cognitive and neuropsychiatric symptoms later in life.2
Swedish:
Kronisk traumatisk encefalopati (Chronic Traumatic Encephalopahy), CTE, är en progressiv neurodegenerativ sjukdom orsakad av upprepat våld mot huvudet. CTE ger en mångfald av symtom som irritabilitet, aggressivitet, förlust av korttidsminnet, depression, svårighet att planera och till slut demensliknande skador i hjärnan. Symtomen utvecklas långsamt och börjar först efter flera år. De som drabbats är de som fått upprepade skador mot huvudet som t.ex. spelare i i fotboll, rugby, och boxare,
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Mackay and colleagues6 now report in the Journal a retrospective, epidemiologic study of former Scottish professional soccer players that provides good news and bad news regarding the potential long-term consequences of playing soccer at the professional level. The authors examined the records of 7676 former players and matched controls from the general population (identified from the Scottish Community Health Index) regarding cause of death and use of medications for dementia. Mortality from common nonneurologic diseases was lower among former elite soccer players than among controls (the good news), but mortality from neurodegenerative diseases was higher and prescriptions of dementia-related medications were more common among former players (the bad news). These results are similar to those from a study involving former National Football League (NFL) players conducted by the Centers for Disease Control and Prevention, in which all-cause mortality was lower among former NFL players than in the general population but neurodegenerative mortality was higher.7 Another study involving former NFL players included a comparison group of former Major League Baseball players and found that all-cause mortality, cardiovascular mortality, and neurodegenerative mortality were higher among the former NFL players.8 These results suggest that factors that vary in these two sports, such as body habitus and exposure to repetitive head impacts, rather than common factors such as overall physical activity could be responsible for the differences.
Professional soccer players do not share the body habitus of American football players, but they do share the exposure to repetitive head impacts through routine heading of the ball. An average player heads the ball 6 to 12 times per game (in addition to heading drills at practice) and thousands of times during a career. In small case-series studies, heading has been associated with altered cerebral neurochemistry,[Swedish: se härunder]9 diminished white-matter integrity,10 and cortical thinning11 in professional soccer players without obvious concussion. There are also case reports of former professional soccer players with dementia whose brains were found in postmortem examinations to have CTE with or without other coexisting neurodegenerative diseases.12
Swedish:
Neurochemistry = Neurokemi = läran om hjärnans kemiska uppbyggnad och funktion. Neurokemisk forskning bedrivs ofta i samarbete med farmakologisk forskning, och man arbetar då med att analysera signalsubstansers funktion och hur de påverkas av tillförda preparat.
Swedish:
Neurochemistry = Neurokemi = läran om hjärnans kemiska uppbyggnad och funktion. Neurokemisk forskning bedrivs ofta i samarbete med farmakologisk forskning, och man arbetar då med att analysera signalsubstansers funktion och hur de påverkas av tillförda preparat.
These new findings by Mackay and colleagues should not engender undue fear and panic among soccer players, parents, and coaches. As the authors of the current study indicate, it is not possible to generalize their findings among male former professional soccer players to participants in recreational, amateur, or collegiate-level soccer. Parents of children who headed the ball in youth or high-school soccer should not fear that their children are destined to have cognitive decline and dementia later in life. Rather, they should focus on the substantial health benefits from exercise and participation in a sport that their children enjoy. However, it is also important that the findings from the current study lead to research and increased awareness of the potential short-term and long-term consequences of heading the ball in amateur soccer.
The article by Mackay and colleagues adds to the evidence that repetitive head impacts in some contact and collision sports may increase the risk of neurodegenerative disease and dementia. Research on the neurologic consequences of heading in soccer is needed, including studies involving female former professional soccer players and male and female amateur soccer players, as well as prospective longitudinal investigations to examine possible relationships between heading and neurodegenerative disease in order to confirm or refute the findings of Mackay and colleagues. Perhaps, however, there is already adequate evidence that repeated blows to the brain from heading in professional soccer is an occupational risk that needs to be addressed.
