November 13, 2006
Study Probes ALS Risk, Severity Factors
A study conducted at the MDA/ALS Center at Massachusetts General Hospital in Boston between 1998 and 2002 compared 95 people with ALS with 106 without the disease to identify factors that may influence susceptibility to amyotrophic lateral sclerosis (ALS) and its rate of progression after it develops.
Robert Brown, who directs the center, and Merit Cudkowicz, who treats patients there and has had MDA funding to conduct several ALS studies, were investigators on this project, which was funded in part by MDA and published in the September issue of Amyotrophic Lateral Sclerosis.
ALS patients were more likely than the unaffected (control) group to report exposures to pesticides and lead; to report an average of 14.7 years of education, compared with 16.1 in the control group; not to have served in the military (contradicting other findings showing military service to be an ALS risk factor); and to have stopped smoking slightly later than control group subjects.
Factors associated with a faster rate of disease progression were bulbar
(mouth and throat) muscle onset of the disease; a shorter time from onset of
symptoms to diagnosis; and, confusingly, military service.
The study’s authors note a small sample size and possible bias in the selection
of study participants (with veterans more likely to be cared for at VA hospitals)
or in the subjects’ recall of exposures as potential sources of error.
Lorene Nelson, chief of the Division of Epidemiology at Stanford (Calif.) University
School of Medicine, conducted a study in Washington state from 1990 to 1994
in which cigarette smoking and dietary fat intake were identified as associated
with ALS development. That study included 161 people with ALS and 321 without
the disease.
Nelson, who now has MDA funding, noted that the use of spouses and friends as control subjects, which tends to minimize differences in the two groups, might also bias the results toward not finding factors specifically associated with ALS.