The presence of a bird in your house could multiply your
chances of developing multiple sclerosis by a factor of
two or more. On the other hand, if your pet is a cat, you
could cut your risk by half. Astonishing, but true, according
to the findings of a recently concluded epidemiological
study by Dr. Parviz Ghadirian, professor of Nutrition at
the Université de Montréal and director of
the university hospital (CHUM) epidemiology unit. The study
compared the living habits of 200 Montrealers suffering
from MS with those of a control group that did not have
the disease. "We don't know precisely what may be the
factor with birds, but the results suggest a virus they
carry may act as a vector for multiple sclerosis,"
says Dr. Ghadirian. Other epidemiological studies have
also shown a similar link.
As for cutting your risk of getting MS with a cat, the UdeM
researcher maintains the effect could be of a psychological
nature, perhaps a form of zootherapy: "We don't have
an explanation there either, but it is known that the presence
of an animal companion, like a cat or dog, improves the
quality of life and their owners have less arthritis and
other chronic complaints, and suffer less from hypertension."
Professor Ghadirian's research also brings to light a difference
between men and women: the beneficial effect of having a
cat is more pronounced among men (70% less risk versus 40%
less for women). But the negative effect of keeping birds
is significant only among women (2.5 times higher).
"If a virus is the cause with birds, the difference
between men and women could be explained by the fact that
women are in contact with the animal longer if they stay
at home or because they're the ones that change its litter,"
the researcher says.
The Ghadirian study also revealed another previously unknown
factor. Smoking 20 or more cigarettes a day doubles the
risk of contracting MS compared to the risks to a non-smoker.
"Smoking appeared as the highest environmental risk,
and this is the first time the link has been established
in a control-group study," he says.
Multiple sclerosis is a degeneration of the central nervous
system (the brain and spinal cord) characterized by scattered
hard (sclerotic) areas of scarring where myelin, the fatty
layer of insulation around neurons, has been destroyed.
In an earlier study, Dr. Ghadirian found that a high
consumption of animal fats doubles the risk of MS, while
consumption of edible fibers and cereals reduces risk by
about 40%. "Which means it's easy to reduce the risk
of developing this disease," the epidemiologist says.
"Stop smoking and develop good eating habits."
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Funding: Association de la sclérose en plaques de