Good health hygiene is linked with a higher risk of Alzheimer’s Disease (AD) and dementia. This is according to a new study published this week. Although it seems ironical, the study seems to suggest that living in a wealthy, developed, “first-world” country and being exposed to fewer bacteria and viruses appears to raise the risk of you getting Alzheimer’s. The study was published in Public Health, and Evolution Medicine. According to the study, industrialized countries with better sanitation and water quality had significantly higher rates of Alzheimer’s and dementia than developing countries where bacteria and viruses run rampant.
Researchers from Cambridge University analyzed data from the World Health Organization (WHO) and found that some of the wealthiest- and most hygienic countries in the world, such as Iceland, Switzerland, France, and the UK, had much higher rates of people with dementia and Alzheimer’s. This led researchers to ask the question whether differences in microbial diversity, that is, exposure to fewer bacteria and viruses, is having an impact on patterns of age-adjusted Alzheimer’s Disease rates between countries. That is how they came up with their conclusion that hygiene is positively associated with AD risk.
This idea is not new but has a long history
This idea is not new; known as the “hygiene hypothesis”, it suggests that there is a direct relationship between cultures with higher rates of cleanliness and lower rates if infectious diseases and increased risk of numerous conditions. According to the theory, by exposing ourselves to fewer bacteria and viruses, we deprive our immune systems of opportunities to build up a strong immune response.
The hygiene hypothesis has been studied in the past in relation to allergies, autoimmune conditions, and asthma. Now, Alzheimer’s is added to the list. Research for long has indicated that Alzheimer’s and dementia rates are higher in industrialized countries without giving an explanation, the study tend to give the explanation. But at the moment, the study is just a theory, with plenty of people who don’t agree with it. The study proves only an association, not a causation, leaving plenty of openings for alternative explanations. Like how many other factors are associated with industrialization and urbanization that tend to explain higher rates of immune-related disease.
Then, there is the challenge of proving that Alzheimer’s belong to the group of immune-related diseases. Now, back to the study, it continues to say that cleaner, more bacteria-virus-free environments do seem to be associated with higher rates of many diseases. Researchers used Ghana as one example, where they used long-term population studies to show that as a country industrializes, rates of immune-relate diseases such as lung diseases continue to rise. One interesting research from Li Wen of Yale and Alexander Chervonsky of the University of Chicago, which studied mice raised in germ-free environment, showed that they developed severe diabetes.
Interpreting out the data, the study found a 12 percent higher rate of Alzheimer’s in countries with low rates of infectious diseases, Switzerland and Iceland used as examples. Compared with countries at the low end of the spectrum such as Ghana and China.