Recent post in sci.space.news by Andrew Yee

Here is the full quote of the message in sci.space.news
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Radiological Society of North America
Oak Brook, Illnois

Contact:
Linda Brooks, 630-590-7762

Prolonged space travel causes brain and eye abnormalities in astronauts

Magnetic resonance imaging (MRI) of the eyes and brains of 27 astronauts
who have spent prolonged periods of time in space revealed optical
abnormalities similar to those that can occur in intracranial
hypertension of unknown cause, a potentially serious condition in which
pressure builds within the skull. A retrospective analysis of the MRI
data appears online in the journal Radiology.

A team of researchers performed MRIs and analyzed the data on the 27
astronauts, each of whom were exposed to microgravity, or zero gravity,
for an average of 108 days while on space shuttle missions and/or the
International Space Station (ISS), a habitable research facility that
has been orbiting the earth since 1998. Eight of the 27 astronauts
underwent a second MRI exam after a second space mission that lasted an
average of 39 days.

"The MRI findings revealed various combinations of abnormalities
following both short- and long-term cumulative exposure to microgravity
also seen with idiopathic intracranial hypertension," said Larry A.
Kramer, M.D., professor of diagnostic and interventional imaging at The
University of Texas Medical School at Houston. "These changes that occur
during exposure to microgravity may help scientists to better understand
the mechanisms responsible for intracranial hypertension in non-space
traveling patients."

Among astronauts with more than 30 days of cumulative lifetime exposure
to microgravity, findings included expansion of the cerebral spinal
fluid space surrounding the optic nerve in nine of the 27 (33 percent)
astronauts, flattening of the rear of the eyeball in six (22 percent),
bulging of the optic nerve in four (15 percent) and changes in the
pituitary gland and its connection to the brain in three (11 percent) of
the astronauts. The pituitary gland secretes and stores hormones that
regulate a variety of important body functions.

The same types of abnormalities are observed in cases of intracranial
hypertension where no cause can be found for increased pressure around
the brain. The pressure causes swelling of the juncture between the
optic nerve and the eyeball which can result in visual impairment.

Bone mineral loss and muscle atrophy are some of the known effects of
zero gravity on astronauts. With the onset of longer excursions in space
afforded by the ISS, visual changes have also been observed and are now
being studied.

"Microgravity-induced intracranial hypertension represents a
hypothetical risk factor and a potential limitation to long-duration
space travel," Dr. Kramer said.

William J. Tarver, M.D., M.P.H., chief of flight medicine clinic at
NASA/Johnson Space Center, said the agency has noted changes in vision
in some ISS astronauts, the origin of which is not yet fully understood.
No astronauts have been considered ineligible for space flight duties as
a result of the findings, which he said are suspicious but not
conclusive of intracranial hypertension.

"NASA has placed this problem high on its list of human risks, has
initiated a comprehensive program to study its mechanisms and
implications, and will continue to closely monitor the situation," Dr.
Tarver said.

###

"Orbital and Intracranial Effects of Microgravity: Findings at 3-T MR
Imaging." Collaborating with Dr. Kramer were Ashot Sargsyan, M.D., Khader M.
Hasan, Ph.D., James D. Polk, D.O., and Douglas R. Hamilton, M.D., Ph.D.

Radiology is edited by Herbert Y. Kressel, M.D., Harvard Medical School,
Boston, Mass., and owned and published by the Radiological Society of North
America, Inc. (http://radiology.rsna.org/)

RSNA is an association of more than 48,000 radiologists, radiation
oncologists, medical physicists and related scientists committed to
excellence in patient care through education and research. The Society
is based in Oak Brook, Ill.

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This is bad news for any manned flights to Mars. This abnormalities
appear just after only 108 days. A round trip to Mars would require
around 500 days in deep space at least.

It is obvious that artificial gravity is needed for relatively "short"
trips for humans to survive. I have already mentioned other dangers
like solar flares and radiation in general. The now in Mars cruise
Curiosity rover is measuring the radiation levels... I expect also bad
results for any unshielded crew.

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On 15/03/2012 1:52 AM, jacob navia wrote:
..

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This is bad news for any manned flights to Mars. This abnormalities
appear just after only 108 days. A round trip to Mars would require
around 500 days in deep space at least.

It is obvious that artificial gravity is needed for relatively "short"
trips for humans to survive. I have already mentioned other dangers like
solar flares and radiation in general. The now in Mars cruise Curiosity
rover is measuring the radiation levels... I expect also bad results for
any unshielded crew.

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I'm left to wonder what the ratio of these effects exist in the general
population. As there was no control group, there is little emperical
evidence.