In this presentation, Dr. David Perlmutter discusses a 2013 study from Evolution, Medicine, and Public Health that examined the relationship between national levels of gut parasites (as a proxy for microbial exposure) and age‑adjusted Alzheimer’s disease burden. The data show that countries with higher parasite prevalence and lower hygiene standards—such as Sudan, Ethiopia, and Nigeria—have markedly lower rates of Alzheimer’s, whereas highly sanitized, low‑parasite nations like the United States, Iceland, and Germany exhibit higher disease prevalence. Perlmutter frames these findings within the hygiene hypothesis, suggesting that reduced microbial diversity from modern cleanliness practices may impair immune regulation, increase inflammation, and elevate risk for neurodegenerative diseases. He cautions that while the study demonstrates correlation, not causation, it highlights the potential protective role of a diverse gut microbiome and raises concerns about over‑use of antibiotics, chlorinated water, and excessive hand sanitizers. The talk concludes with a call for further research to clarify causal mechanisms and to consider preserving microbial diversity for brain health.
Chapters
You've got to wash your hands. You've got to pay attention to your hygiene. Why? Because if you don't, then you'll get the dreaded germs and all kinds of terrible things will happen. Well, it turns out, oddly enough, that new research is indicating that in those countries who pay less attention to hygiene, where their lifestyle is not as sanitary as ours is in Western cultures, These countries may have less risk for some really important diseases, including Alzheimer's disease. Let's take a look at a new study. This is a report that came to us from Evolution, Medicine, and Public Health, August of 2013, and it's a study that looks at the— what is called the microbial environment and age-adjusted disease burden. In other words, this is a study that compares a country's hygiene based upon the amount of parasites that people have with risk for Alzheimer's disease. And in this first section, you'll notice that towards the right of your screen, those are countries in whom individuals have higher levels of parasites, less hygiene, more parasites in their gut, and so significant changes that we in Western cultures would think would necessarily be bad. Countries like Sudan, Ethiopia, Nigeria, Chad, Angola, Kenya, These are places where there are lots and lots of parasites that infect people. Now, this next slide shows the increasing prevalence of Alzheimer's disease, and you'll notice that the further to the left you go— countries like Iceland and United States, Denmark, Austria, and Germany— these are actually the same countries that have the highest degree of hygiene, the least amount of parasites. What the study is demonstrating is that in those countries that have the highest level of diversity of the microbes living in the gut, they have the best functioning immune systems, the least amount of inflammation, and the least risk for things like Alzheimer's disease. Now the study only looked at Alzheimer's, but I suspect we're going to learn very soon that this information can in fact be generalized. We have something called the hygiene hypothesis, and what does that mean? It means that our obsession with cleanliness, you know, finding these hand sterilizers at the end cap of every aisle in the grocery store, may in fact be doing more harm than good. That the bacteria, especially diverse types of bacteria living within the gut of humans, is actually a very good thing. Now what I've done is I've actually superimposed these 2 graphs. And what you see here is increasing parasitic stress on the right side of your screen, more parasites. being associated with lower risk for Alzheimer's. And on the left side of the screen, you see those countries where they have less numbers of parasites in the gut having much higher levels of things like Alzheimer's, in this case specifically Alzheimer's. And what the authors concluded is that variation in hygiene may partly explain global patterns in Alzheimer's disease rates. Microorganism exposure may inversely be related to Alzheimer's disease risk. These results may help predict Alzheimer's disease burden in developing countries where microbial diversity is rapidly diminishing. So I want to be again clear that this is an interesting study, and we often talk about causation and correlation. In this case, we have a correlation between higher levels of parasites and lower risk for Alzheimer's. Does that mean that parasites are somehow causing a reduced risk. I obviously can't say that, but I think it nonetheless very important information because it brings to our attention this notion that there may be some very important protective effects in terms of health of having a very diverse gut bacterial population that again we don't want to threaten with things like chlorinated water and overusage of antibiotics. I'm Dr. David Perlmutter.
