Do Highly Sanitized Areas Increase the Risk of Alzheimer's Disease?

A recent study suggests that Alzheimer's disease could be linked to an increased risk of highly sanitized areas. In fact, previous findings show that similar environments may actually be associated with a higher stroke risk due to the disappearing number of gut bacterium Helicobacter pylori (H. pylori).

This new study looks at evidence regarding the hygiene hypothesis, which states that people in wealthier nations are less exposed to viruses, bacteria and other microbes. While this can prevent disease, it can also cause other problems that could potentially halt the immune system from properly functioning.

The study found that countries where everyone had access to clean drinking water had a 9 percent increased risk of getting Alzheimer's than countries with clean water access for just half of the population.

As part of the immune system is composed of a type of white blood cell known as a T-cell that fights off infection within the body, T-cell deficiency has been linked to types of inflammation found in the brain or commonly found in those with Alzheimer's.

"The 'hygiene hypothesis', which suggests a relationship between cleaner environments and a higher risk of certain allergies and autoimmune diseases, is well established," lead study author Molly Fox, a Cambridge Alumna, who conducted the research at Cambridge's Biological Anthropology division, via a press release. "We believe we can now add Alzheimer's to this list of diseases."

Looking at data from 192 countries, researchers found that those with higher levels of sanitation tended to have higher rates of the disease. The study also showed that countries that had more than three-quarters of the population living in an urban environment had a 10 percent higher risk for Alzheimer's than those in the country.

However, they conclude that the study does not cancel out other lifestyle factors including education, diet and overall health.

More information regarding the study can be found via the journal Evolution, Medicine and Public Health.