A sport whose sole aim is to cause brain damage to another person
is not a "noble art". It has no place in a civilised society, says a
leading neuroscientist
WHEN the 2013 National Football League season kicks
off in the US next month, players will have an added layer of protection
to go with their helmets and shoulder pads: an independent neurologist at every game to assess them for signs of concussion after receiving a blow to the head.
Head injuries are an occupational hazard
for American footballers and a major issue for the NFL. Thousands of
retired players are suing the league for negligence and fraud, claiming that the league knew about the long-term risks but hid them.
The condition they fear is chronic
traumatic encephalopathy (CTE), previously called punch drunk syndrome,
boxer's dementia or dementia pugilistica. This causes progressive memory
problems, personality change and slowness of movement. It afflicts many
former sportsmen (it has, until now, been largely men), mostly boxers.
The pathology of CTE is well known. In the
1980s, John Corsellis of the Maudsley Hospital in London documented it
in a series of papers, culminating in a 1989 review in the BMJ.
He found that many nerve fibres showed
evidence of tearing, with some being completely torn, and also reported
widespread brain degeneration. He also described how many neurons were
filled with tangles of protein, one of the hallmarks of Alzheimer's
disease.
Other researchers later showed that the
brains of men with CTE had a second type of protein deposit called
amyloid, another hallmark of Alzheimer's.
While there is no doubt that these problems are caused by repeated blows to the head, until recently it wasn't known how.
Blows to the head cause two different
kinds of injury. The face is cut and bruised by direct impacts, but
damage to the brain is caused largely by rotational acceleration of the
cerebral cortex around the much smaller midbrain and spinal cord. This
damage may be aggravated by boxing gloves since they add weight and thus
energy to punches, causing more rotational acceleration.
Brain tissue is largely a soft mass but
the blood vessels within it are fibrous and strong, like wires across
cheese. When the head is hit, especially with a rotational movement, one
of two things can happen. Either a blood vessel can snap, leading to a
haemorrhage, or there can be microscopic tearing of the tissue around
the vessel.
Large haemorrhages are what cause boxers
to fall into comas and occasionally die during bouts, but the
microscopic tears to blood vessels can be no less damaging in the long
run.
The first thing to note is that sportsmen
who were frequently injured in this way in their youth often develop
characteristic behaviour patterns as they get older. These are the
problems often reported in lurid stories about troubled ex-boxers:
depression, drug and alcohol abuse and violent tempers. All are
consistent with underlying damage to the frontal cortex, which controls
executive functions such as impulse control.
This is not to say that all ex-sportsmen
with these problems have CTE, but it is clear that in some cases it is a
contributing factor.
What's more, recent experiments in mice
have indicated that protein tangles and amyloid deposits can slowly
spread from neuron to neuron. The distribution of the tangles in CTE is
consistent with this, forming first around blood vessels before
spreading.
With these findings we can now formulate a
plausible hypothesis as to why repeat head injuries to young men in
their teens and 20s lead to personality changes later in adult life and
dementia in old age: rotational head injury induces damage, especially
around blood vessels, leading to local tangle formation, followed by a
slow spread of destruction.
Clearly, considerable effort should be
expended in all sports to minimise head injuries. Soccer has already
done the right thing by replacing heavy leather balls with lighter
plastic-coated ones. American football appears to be going in the right
direction. But other sports have some way to go.
In ice hockey, the role of the "enforcer",
whose main job appears to be beating up the opposing team's players,
should be abolished. And in all sports where there is any risk of head
injury – rugby for example – players should be monitored to keep an eye
on the damage. Clearly, all who play and coach these sports should be
aware of the risks.
Boxing, however, is a special case. No
other sport has the express goal of causing injury to the brain. That is
certainly the aim of professional boxing. Even in amateur boxing blows
to the head are crucial, and protective headgear may not stop injury
from rotational acceleration.
Corsellis put it best: "My opinion is that
the brain should not be the target in any sport, and no amount of
juggling with the regulations can take away the risk. Experienced and
outstanding boxers are themselves aware of the risk, difficult as it may
be for them eventually to call a halt. Barry McGuigan said 'Boxing
damages your brain: don't let anybody tell you different'."
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