By Richard Robins
LONDON, ENGLAND -- June 21, 2001
-- Exposure to airborne particulates increases the exacerbation rate in
multiple sclerosis (MS) patients, according to a study presented today
at the 17th World Congress of Neurology here.
Peripheral microbial infections are
known to increase MS exacerbations, according to Mervi Oikonen of the Aerobiology
Unit at the University of Turku, Finland. Susceptibility to such infections
of the airways increases with a rise in airborne particulates, through
a complex of immune system and respiratory tissue changes.
To determine whether there is a direct
link between air pollution levels and MS exacerbations, Dr. Oikonen and
colleagues compared levels of particulates, pollen, carbon monoxide, and
other pollutants to hospital records of MS patients over 15 years. To allow
for the presumed delay in health effects following exposure to pollutants,
a one-month time lag between pollutant levels and exacerbation reports
was built into the study.
Analysis showed that there was a
significant correlation between the two variables. Specifically, the odds
ratio of occurrence of relapse was four times as great after a peak concentration
of inhalable particulate matter. Months of high particulate levels were
followed by months of high relapse rates, and low particulate levels led
to low relapse rates in the following month. Other pollutants did not show
the same correlation.
"Our data shows that inhalable particulate
matter may have a role in the development of MS exacerbations," Dr. Oikonen
said.
Apart from predisposing to infections,
he noted that the general activation of the immune system through mechanical
irritation of the airways may also promote exacerbation. His group is currently
undertaking a prospective examination of the immunological status of MS
patients exposed to variable pollution levels.
Special to DG News