Marc Weisskopf, Ph. D.; Harvard University School of Public Health; PRMRP Idea Development Award
The research that I'm presenting here at the Military Health Research Form focuses both on ALS and Parkinson's Disease where we do epidemiology or population health research and the questions we ask are there particular factors we can predict one's risk of getting ALS or Parkinson's Disease. So, the first aspect of the research that I'm presenting here is whether service in the military over any period we're looking at people who would have served as far back as World War I up until the Gulf. None of our research is based on Gulf War veterans. It's all veterans from earlier on. And, we're asking first the very simple question of whether service in the military is related to an increased risk of ALS. We do epidemiological studies so they are basically sort of statistical analyses of large cohorts of people of large databases so for this particular work we've collaborated with the American Cancer Society and they have a study called The Cancer Prevention Study II or CPS II that they formed in 1982 of over one million of U.S. men and women. So, we came along later to collaborate with them and asked "Can we look at your cohort and ask whether people died from ALS". So, we looked at the men in that study to say whether their reporting of service in the military, was that related to a higher risk of ALS. And, in fact, we found that was the case because it didn't seem to matter what branch of military service someone had served in. They were all at more or less equal risk of ALS. It also did not seem to be related to how long they served and it was not necessarily related to a particular war time period. So, what we take from that is there seems to be something that's much more common to military experience that may put someone at increased risk for ALS. Additionally, we were very interested in particular in chemical exposures that people may have had and in particular in interested in pesticides and herbicides that have been reported in literature that there may be a connection between pesticide exposures and risk of ALS. And, we set out to look at that and in fact, didn't really see anything for pesticides or herbicides; maybe something subtle that we really couldn't pull out. But, somewhat surprisingly, it turned out that there was a rather strong relationship with formaldehyde exposure. And, this was even stronger when we looked at how many years someone had reported being exposed to formaldehyde. So, there is a very strong relationship between how many more years they reported being exposed to formaldehyde the higher the risk of ALS was. So, that was sort of an intriguing finding that was in fact, not an apriori hypothesis and it's definitely a finding that we consider exciting and worth following up. It turns out actually formaldehyde exposure is very wide spread and in fact, it's very big in the news these days because there is a lot of formaldehyde in FEMA trailers that were sent down to New Orleans after Katrina. We're also interested in another neurogenerative disease, Parkinson's disease, which is the second most common neurogenerative disease. After all of the ALS work, there were some reports floating around that perhaps, there was some connection between military service and Parkinson's disease. So, we looked at it in our sample and did not see that association. That's not to say it's not there in some particular subgroups of military folk, but overall in our group, we did not see any association and again, it didn't matter what branch of service someone had served in or what time period. We didn't see any connection. We were also interested again in Parkinson's disease and various chemical exposures and we then asked whether people's reporting of regular exposure to pesticides in 1982 was related to their subsequent development of Parkinson's disease. And, in fact, we found a very strong association. People who reported regular exposure to pesticides were at 70% increased risk of getting Parkinson's Disease compared to people who were not exposed.
This research that CDMRP is funding for ALS is particularly unique because ALS has its problem that it's actually a very rare disease. So, you need to have a huge cohort to be able to expect to get enough ALS cases to make any scientific conclusions on that. It's one of, if not the first large prospective cohort study of risk factors for ALS. And, that being the case, it provides some of the strongest evidence that is out there for the various factors that we're exploring.