Study Links Head Trauma among
Professional Football Players to
Premature Memory Loss
Would-be football stars have long had to weigh the benefits of an NFL career—fame and
fortune—against the painful, sometimes crippling joint and bone degeneration they are
apt to suffer during their retirement years. New evidence suggests that the hard knocks
of the gridiron may encourage another, more ominous kind of degeneration.
“We’re seeing hints that mild cognitive impairment (MCI), a condition that often
precedes Alzheimer’s disease, is more common among former NFL players than the
general population of that age,” says Stella Karantzoulis, PhD, assistant professor of
neurology and a clinical neuropsychologist at the Pearl Barlow Center for Memory
Evaluation and Treatment at the Silberstein Alzheimer’s Institute of NYU Langone
Medical Center. Dr. Karantzoulis and her research team recently presented new find-
ings on the increased risk of MCI among former NFL players at the annual International
Conference on Alzheimer’s Disease in Paris.
In 2005, a sports medicine researcher at the University of North Carolina
reported on a survey of nearly 3,700 former NFL players. Among players who re-
sponded (70%), those who had experienced three or more concussions had three
times the prevalence of significant memory problems and five times as many diagnoses
of MCI, compared to players who reported no concussions. The data also hinted that
former NFL players were more likely than other men of their age to be diagnosed with
Alzheimer’s disease earlier in life.
Those findings, published in the journal Neurosurgery, depended on the poten-
tially fallible recall of former athletes and their family members. To follow up, a second
survey, which focused on memory problems, was sent to NFL retirees to recruit some
of the players for a clinical trial of MCI.
Dr. Karantzoulis and lead author Christopher Randolph, PhD, professor of
neurology and a clinical neuropsychologist at Loyola University Chicago School of
Medicine, identified those retirees with neurocognitive profiles consistent with MCI.
Drs. Karantzoulis and Randolph then identified a group of 41 cognitively normal men of
the same ages, education levels, and ethnicities as 41 former NFL players, as well as a
group of 81 patients already known to have MCI (from each of their respective institu-
tions) to serve as comparison groups.
The 41 former players showed clear signs of cognitive impairment on a battery
of tests, compared to the healthy control group—and the pattern of impairment was
strikingly similar to the MCI groups. “This finding was especially unsettling because
the former NFL players were a relatively young group (64 years old, on average) and
significantly younger than the MCI group,” says Dr. Karantzoulis.
The researchers hypothesize that even minor head trauma, routinely experienced
in this high-impact sport, can add up to a premature degeneration of brain tissue. That,
in itself, may trigger a progressive dementia, or it may simply leave the brain less able to
cope if the Alzheimer’s disease process should strike in later life.
For Those with Graying Hair,
a Silver Lining
Raising hopes for the salt-and-peppered among us, researchers at NYU
Langone Medical Center have discovered the root of gray hair—in mice, that
is. Mayumi Ito, PhD, professor of dermatology and cell biology, has discovered
how two types of stem cells in the hair follicle collaborate to generate vibrant
tresses. She figured out that when a critical signaling network of proteins,
known as the Wnt pathway, is disrupted, the pigment is no longer produced,
and the hairs that emerge from the follicle are gray. “Previous research
suggested that the epithelial stem cells and the melanocyte stem cells
collaborate to make pigmented hair,” explains Dr. Ito, “but no one knew
exactly how the pigmenting happened.”
Dr. Ito knew that the Wnt signaling pathway was a key player in the
regulation of other adult stem cells, like those which produce the lining of the
intestine. It was also well known that Wnt was essential for hair regeneration.
“I was curious whether Wnt also influenced the neighboring melanocyte stem
cells,” she explains.
Typically, in the hair follicle, Wnt signaling coordinates the activity of the
epithelial and melanocyte stem cells and turns them on at the same time, notes
graduate student Piul Rabbani, who conducted many of the experiments. Once
the stem cells are active, the epithelial stem cells produce a hair strand, and
the melanocyte stem cells produce melanocytes that crank out pigment that is
injected into the hair strand, giving it its color.
Dr. Ito and Rabbani tested what would happen if they blocked the Wnt
signal in the melanocytes. Over the course of three years, they used a strain
of mice with faulty Wnt signaling just in the melanocyte stem cells. When hair
replacement occurred in those mice, and their coats began to come in, “you could
tell right away,” says Rabbani. The unaltered mice had shiny black and brown
coats. The mice with Wnt signaling missing from the melanocytes were gray and
white. “It was pretty exciting because that’s what we were hoping to see,” adds
Rabbani. The study was published in the June 11, 2011, issue of the journal Cell.
“Wnt is a very important signal for many biological processes,” explains
Dr. Ito. “But we are the first to show its role in melanocyte stem cells and prove
its role in hair pigmentation.” If a shortage of Wnt in the melanocytes leads to
gray hair, would amping up the quantity lead to a dark shiny coat? Not quite,
says Rabbani. In another strain of mice, increasing the Wnt signaling actually
exhausted the melanocytes. “We need the perfect balance of Wnt—the timing
and the quantity are both very important.”
While the research was limited to mice, Dr. Ito says the follicles function
similarly to those found in humans. Ultimately, these findings could lead to
a therapy that would stave off gray hair, but that’s “still a ways off,” cautions
Rabbani. “Hang on to the tweezers and hair dye,” she says, at least for now.
Of Premies, Micropremies, and the Microbiome
When Vikram Chari was born at NYU Langone Medical Center’s Tisch Hospital, his par-
ents, Santhi and Shreyas, were afraid to name him. At 25 weeks old, he weighed only 1. 5
pounds, and he spent his first weeks in an incubator, his right lung repeatedly collapsing.
As he improved, the staff of the Neonatal Intensive Care Unit (NICU) suggested that
Santhi give him kangaroo care, a therapy of skin-to-skin contact between mother and
infant with well-documented benefits, including fewer acute infections, faster weight
gain, and better long-term health. Every few days for the next four months,
Vikram was placed on his mother’s bare chest and covered with blankets
for an hour or two. Her body warmed his and regulated his breathing
and heart rate. “It was amazing to be able to help him,” says Santhi.
Introduced in 1978 at a Colombian hospital that lacked
enough incubators, kangaroo care became popular worldwide
after the World Health Organization endorsed it in 1999. It’s
less common in the US, where NICUs rely more on incubators
due to fears of fatal infections or the technical challenges of
moving a baby to its mother’s chest when that baby is hooked
up to a ventilator. Since 1981, the number of premature and
low–birth-weight babies born in the US has increased 35%, ac-
counting for half of all infant deaths.
Last year, the National Institutes of Health awarded Karen
Hendricks-Munoz, MD, associate professor of pediatrics and chief of the
Division of Neonatology, a two-year, $424,000 grant to continue her research
into the biological mechanisms that underlie the effectiveness of kangaroo care. Her
focus is the transfer of the microbiome, or unique bacterial signature, of the mother
to her infant, a process that may help develop and bolster the baby’s immune system.
“It’s thought that babies are born sterile and, over the next 24 to 48 hours, begin to
acquire their own microbiome,” says Dr. Hendricks-Munoz. “An infant absorbs a lot of
the mother’s microbiome through all of the interaction: delivery, breast-feeding, ma-
ternal touch, kissing.”
For more than a year, Dr. Hendricks-Munoz and her colleagues have
collected saliva, breast milk, and skin and stool samples for analysis
from a diverse population of mothers and infants at Metropolitan,
Bellevue, and Tisch Hospitals, where kangaroo care has been
used for more than a decade. Pinpointing the role of the mi-
crobiome may convince other NICUs to increase their use
of the therapy, which will help babies thrive and save hos-
pitals money. Healthier infants go home sooner. Expanding
kangaroo care may also help shrink troubling racial and
ethnic disparities in infant mortality rates in the US, says Dr.
Hendricks-Munoz. To that end, the study also investigates cul-
tural practices that may pose barriers to its fuller adoption.
Though he spent his first few months at home hooked up to
a machine that monitored the oxygen in his blood, today Vikram is a
small but healthy 18-month-old. Developmentally, he’s only a bit behind
full-term toddlers his age. He constantly smiles, which amazes his mother. “He
went through so much,” she says. “More than I have in my entire life.”
Illustrations: Wes Bedrosian
research & clinical spotlight
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