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Herpesvirus gets to brain via nose
By Laura Sanders
After setting up shop in people’s nasal
mucus, human herpesvirus 6 may travel
along olfactory cells right into the brain,
researchers report August 16 in the
Proceedings of the National Academy of
Sciences.
HHV- 6 causes the common childhood
infection roseola, marked by a chest rash
and a high fever. “Everyone is exposed
to this,” says study coauthor Steven
Jacobson of the National Institute of
Neurological Disorders and Stroke in
Bethesda, Md. “You have it. I have it.”
Despite the virus’s ubiquity, very lit-
tle is known about it. In some people
(researchers don’t know how many), the
virus can infect the brain, where some
scientists believe it may contribute to
neurological disorders such as multiple
sclerosis and a form of epilepsy.
Other viruses such as herpes simplex,
Human herpesvirus 6 (shown in an
electron micrograph) infects most
people during infancy or toddlerhood.
influenza A and rabies can invade the
brain by shooting through the nose,
so Jacobson and his team wondered
whether HHV- 6 could do the same.
Researchers found high levels of
HHV- 6 in the olfactory bulb, a smell-
related part of the brain, in two of three
autopsy brain samples. The team then
looked at nose mucus and found the
virus in 52 of 126 samples. “We were
surprised to find so much in the nasal
mucus,” Jacobson says.
Apnea linked to
later dementia
Sleep disorder may cause
cognitive decline in women
By Nathan Seppa
Breathing irregularities that rob the
brain of oxygen during sleep may imperil
a person’s ability to think straight. A
study of women 65 and older finds that
those with seriously disordered breathing have an increased risk of developing
mild cognitive impairment or dementia
in subsequent years, researchers report
in the Aug. 10 Journal of the American
Medical Association.
People with disordered breathing slow
down or stop taking breaths during sleep
and often gasp to catch up. The condition
includes sleep apnea, an abnormal pattern that deprives the brain of oxygen
and intermittently interrupts the deep
sleep needed for satisfying rest.
Previous short-term studies have
linked disordered breathing to cognitive impairment, but long-term data
have been lacking.
In the new study, physician Kristine
Yaffe of the University of California,
San Francisco and her colleagues tested
298 women an average of 82 years
old for sleep problems. None of these
women were cognitively impaired at the
time of the sleep test. The researchers
monitored each woman overnight and
noted any stoppages of airflow in their
breathing as well as arousals from sleep.
About one-third of the patients had
disordered breathing.
When researchers repeated standard
cognition tests on the women roughly
five years later, 45 percent of those who
had disordered breathing had developed
dementia or milder cognitive impair-
ments, compared with 31 percent of
those with no breathing irregularities.
