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72
73
January/February 2018^ DISCOVER^73
LEFT: VICTOR ALVAREZ, MD, VA BOSTON, BU CTE CENTER. RIGHT: MATTHIEU PALEY/NATIONAL GEOGRAPHIC CREATIVE/ALAMY STOCK PHOTO
Football’s Latest
Injury Report
❯
IT’S HARD-HITTING NEWS: Of 111 former NFL players’
brains, 110 showed signs of chronic traumatic
encephalopathy, or CTE. CTE is a brain disease
caused by repeated hits to the head that leads to memory
loss, and mood and personality changes such as increased
impulsivity, violence and depression.
The study, published in July in the Journal of the
American Medical Association and the largest of its kind,
examined the brains of 202 people who had all played
football at some point in their lives. The disease permeated
all levels of the sport; 48 of 53 college players’ and three
of 14 high school players’ brains showed signs of CTE.
However, because the sample included a number of brains
donated by family members who noticed symptoms, it isn’t
representative of all former football players.
Still, Ann McKee, the study’s senior author, thinks the
results warrant changes, such as introducing kids to the
sport when they’re older and limiting the number of games
and full-contact practices.
“Even though this is a biased sample, the sheer volume
of the numbers indicates that the problem is more
prevalent than previously considered,” McKee says. “It’s
concerning.” — TEAL BURRELL
24-Hour
Watch
❯
EARLY BIRD OR NIGHT OWL, you
can thank evolution: Staggered
natural sleep patterns, or chronotypes,
may have kept our species alive.
Having a few members of a group awake
at all times can protect everyone from
predators and other threats. This idea,
known as the sentinel hypothesis, was
proposed in the 1960s and demonstrated in
some birds and rodents.
In July, in Proceedings of the Royal
Society B, researchers described the first
evidence for the sentinel hypothesis in
humans. The team used wrist monitors to
track the sleep patterns of 33 members
of Tanzania’s Hadza people, whose
environment and hunter-gatherer lifestyle
are similar to those of early humans.
The findings: During more than
220 hours of data collection, there were
only 18 one-minute increments when all
participants were soundly asleep. Age had
the strongest influence on chronotype;
participants aged 50 and older were more
likely to be early birds than those 30 and
younger.
“We’re incredibly different from our
ancestors in so many ways,” says Duke
University evolutionary anthropologist
Charles Nunn, a researcher involved in
the study. “Yet understanding that past
can help us understand our behavior and
physiology today.” — GEMMA TARLACH
NORMAL BRAIN SLICE
CTE BRAIN SLICE
The Hadza hunter-gatherer tribe in Tanzania
took part in a study that supported the sentinel
hypothesis, the idea that having someone
awake at all times protects against threats.
Sections of a normal brain (top), compared with a brain with severe
chronic traumatic encephalopathy, or CTE (above), show the extent of the
brain-shrinking damage CTE can do. New research finds the disease affects
football players at nearly every level, including high school.