Sometimes a little dirt may be good for you, right?
A new study suggests that those living in more industrialized countries with better hygiene may be more likely to develop Alzheimer's than those who don't. The reason? A lack of contact with bacteria, viruses and other microorganisms that can lead to problems with immune development and increased risk of dementia.
Indeed the new research has uncovered a "very significant" link between a nation's wealth and hygiene and the Alzheimer's "burden" on its population.
Scientists say that the research gives even more credence to the "hygiene hypothesis" in relation to Alzheimer's: that sanitized environments in developed nations mean less exposure to a variety of bacteria, which could actually cause the immune system to develop poorly and expose the brain to the inflammation associated 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. We believe we can now add Alzheimer's to this list of diseases," said Dr. Molly Fox, who conducted the research at Cambridge's Biological Anthropology division, in a press release.
“There are important implications for forecasting future global disease burden, especially in developing countries as they increase in sanitation," she said.
After factoring in differences in population age structures, the study found that countries with higher levels of sanitation had higher rates of Alzheimer’s. For example, countries where all people have access to clean drinking water, such as the UK and France, have 9 percent higher Alzheimer’s rates than countries where less than half have access, such as Kenya and Cambodia. In general, Alzheimer's at age 80 is more prevalent in North America and Europe compared with other countries.
In other Alzheimer's research this summer, scientists showed that copper seems to prevent the body's ability to clear the Alzheimer's-associated compound amyloid beta from the brain, leading to its accumulation. What's more, copper also seemed to play a role in the production of amyloid beta in the brain.