Head blows linked to slower processing speeds
Friday January 30th, 2015
Repeated blows to the head can lead to slower processing speeds and smaller volumes in some parts of the brain – particularly in boxers, researchers warn today.
Researchers from the Cleveland Clinic in Las Vegas, Nevada, and in Ohio, USA, examined data from 224 professional fighters – 131 mixed martial arts fighters and 93 boxers – all of whom were aged 18 to 44 and had participated in the Professional Fighters Brain Health Study (PFBHS).
The team also analysed 22 people with no history of head trauma, but matched for age and educational attainment. Their findings are published in the Journal of Sports Medicine.
The amount of time the fighters had spent as professional athletes ranged from zero to 24 years, but averaged at four years. The number of professional matches they had competed in ranged from zero to 101, averaging out at ten a year.
All participants underwent an MRI scan to assess brain volume at the start of the study and then annually for 4 years afterwards. Verbal memory, processing speed, fine motor skills and reaction times were also tested to measure their brainpower.
The researchers calculated the Fight Exposure Score (FES), which combines duration and intensity of fight career.
They found that the higher the score the smaller the volume, particularly of the thalamus and the caudate areas of the brain. Each increase in FES was linked to reductions of 0.8% in both these structures.
Smaller volumes and a higher FES score were associated with slower brain processing speeds. Researchers found that there was an estimated 0.19% reduction in processing speed per fight and a 2.1% reduction for each increase in FES.
Fighters with an FES score of 4 were 8.8% slower in processing speed than those with an FES score of 0. Higher FES scores were linked to a heightened risk of cognitive impairment.
The authors found that boxers generally fared worse than martial arts combatants, irrespective of their age, being mentally slower and having smaller volumes in their brain structures.
“Perhaps the most obvious explanation is that boxers get hit in the head more,” they suggest.
“In addition to trying to concuss their opponent, martial arts fighters can utilise other combat skills such as wrestling and jiu jitsu to win their match by submission without causing a concussion.”
The thalamus and caudate could be vulnerable to volume loss in a number of ways, including the rotational movement of the head as a result of punches delivered during a boxing match.
“Not only does it appear that differences in MRI volumetrics associated with fight exposure can be detected in relatively young individuals, but these differences occur in particular subcortical structures,” write the authors.
The FES could help to set criteria for required neurological checks or retirement from the sport, they conclude.
Bernick C, Banks SJ et al. Repeated head trauma is associated with smaller thalamic volumes and slower processing speed: the Professional Fighters’ Brain Health Study. Br J Sports Med 30 January 2015; doi:10.1136/bjsports-2014-093877 [abstract]
Tags: A&E | Brain & Neurology | Fitness | North America
Printer friendly page