Too clean may mean higher risk of dementia
PEOPLE living in developed countries, who tend to have less contact with germs, are more likely to get Alzheimer's, researchers from Cambridge University said in a study published this week.
The study found a strong relationship between high incomes and a sanitised environment, with higher rates of the disease that leads to cognitive decline.
Being excessively clean has already been linked to a rise in allergies and diseases such as asthma and eczema.
"The 'hygiene hypothesis', which suggests a relationship between cleaner environments and a higher risk of certain allergies and autoimmune diseases, is well established," said Dr Molly Fox, lead author of the study.
"We believe we can now add Alzheimer's to this list of diseases."
Published in the journal Evolution, Medicine And Public Health, the study found that countries where all people have access to clean drinking water, such as Britain and France, have 9 per cent higher Alzheimer's rates than countries where less than half have access, such as Kenya and Cambodia.
Prior research has shown that Alzheimer's prevalence in Latin America, China and India are all lower than in Europe, and lower in rural compared to urban areas.
"Exposure to micro- organisms is critical for the regulation of the immune system," wrote the researchers in the study published on Wednesday.