Eaglehouse YL, Talbott EO, Chang Y, Kuller LH.
Participation in Physical Activity and Risk for Amyotrophic Lateral Sclerosis Mortality Among Postmenopausal Women.
JAMA Neurol. 2016 Mar 1;73(3):329-36.
PubMed.
If the body's defenses against oxidative stress are devoted to coping with that induced by strenuous exercise, these defenses may be less able to cope with the oxidative stress associated with an acute exposure to neurotoxicants found in the environment and workplace.
It is becoming increasingly clear that factors implicated in developing disease per se can interact with environmental and lifestyle factors to influence the subclinical progression of neurodegenerative disease. Unfortunately, few epidemiological studies have looked at age at onset as an endpoint in subjects stratified by these environmental and lifestyle risk factors. Even fewer studies have looked at the interactions between age at onset, exposure to environmental factors, and genetic polymorphisms that encode for drug metabolizing enzymes such as glutathione-S-transferase. More work in this area is needed.
There was a really small difference in the exercise levels reported to confer risk. And I take issue with the claim by the paper's authors, and the reporting in this Alzforum article, that patients and controls differed in the number of times per week they engaged in strenuous physical activity (PA). From the JAMA Neurology article: "There was an elevated percentage of deaths from ALS with increasing frequency of strenuous PA in the WHI, with percentage of death from ALS varying from 0.09% for 0 days per week to 0.16% for 4 days per week (P for trend = .06)." In fact, the negative data was not limited to strenuous PA; there was no significant difference in the number of times per week they engaged in any physical activity: "Age-adjusted ALS mortality rates varied from 7.4/100,000 person-years for women who reported no strenuous PA to 10.6/100,000 person-years for women who did strenuous PA on 3 or more days per week (P = .07)."
Arbitrary as it may be, a p-value of 0.05 is the cut-off that convention dictates we consider significant. If it is not a significant difference, we cannot really be sure that it is a difference at all.
Obviously, the well-proven benefits of exercise for general health dramatically outweigh the nonsignificant trend toward an increased risk reported by Eaglehouse et al
Comments
Boston University Chobanian & Avedisian School of Medicine
If the body's defenses against oxidative stress are devoted to coping with that induced by strenuous exercise, these defenses may be less able to cope with the oxidative stress associated with an acute exposure to neurotoxicants found in the environment and workplace.
It is becoming increasingly clear that factors implicated in developing disease per se can interact with environmental and lifestyle factors to influence the subclinical progression of neurodegenerative disease. Unfortunately, few epidemiological studies have looked at age at onset as an endpoint in subjects stratified by these environmental and lifestyle risk factors. Even fewer studies have looked at the interactions between age at onset, exposure to environmental factors, and genetic polymorphisms that encode for drug metabolizing enzymes such as glutathione-S-transferase. More work in this area is needed.
View all comments by Marcia RatnerUniversity of Arkansas for Medical Sciences
There was a really small difference in the exercise levels reported to confer risk. And I take issue with the claim by the paper's authors, and the reporting in this Alzforum article, that patients and controls differed in the number of times per week they engaged in strenuous physical activity (PA). From the JAMA Neurology article: "There was an elevated percentage of deaths from ALS with increasing frequency of strenuous PA in the WHI, with percentage of death from ALS varying from 0.09% for 0 days per week to 0.16% for 4 days per week (P for trend = .06)." In fact, the negative data was not limited to strenuous PA; there was no significant difference in the number of times per week they engaged in any physical activity: "Age-adjusted ALS mortality rates varied from 7.4/100,000 person-years for women who reported no strenuous PA to 10.6/100,000 person-years for women who did strenuous PA on 3 or more days per week (P = .07)."
Arbitrary as it may be, a p-value of 0.05 is the cut-off that convention dictates we consider significant. If it is not a significant difference, we cannot really be sure that it is a difference at all.
Obviously, the well-proven benefits of exercise for general health dramatically outweigh the nonsignificant trend toward an increased risk reported by Eaglehouse et al
View all comments by Steve BargerMake a Comment
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