Better hygiene in wealthy nations may increase Alzheimer's risk

A comparison of Alzheimer’s prevalence across the world using 'age-standardized' data (which predict Alzheimer's rates if all countries had the same population birth rate, life expectancy and age structure) has found a strong correlation between national sanitation levels and Alzheimer's, with better hygiene associated with higher rates of Alzheimer’s.

This fits in with the idea that’s been floating around for a while, that over-sanitized environments reduce exposure to a diverse range of microorganisms, perhaps impairing proper development of the immune system. Hence, the rising incidence of allergies and auto-immune diseases in developed countries.

The study compared data from 192 countries. Higher rates of Alzheimer's were seen in countries with higher levels of sanitation, countries with much lower rates of infectious disease, and more urbanized countries. For example, UK and France have 9% higher Alzheimer's rates than Kenya and Cambodia; Switzerland and Iceland have 12% higher rates of Alzheimer's than China and Ghana; UK and Australia have 10% higher rates than Bangladesh and Nepal.

Differences in levels of sanitation, infectious disease and urbanization accounted respectively for 33%, 36% and 28% of the discrepancy in Alzheimer's rates between countries.

Previous research has shown that in the developed world, dementia rates doubled every 5.8 years compared with 6.7 years in low income, developing countries, and that Alzheimer's prevalence in Latin America, China and India are all lower than in Europe, and, within those regions, lower in rural compared with urban settings.

Having said all that, I would query the reliability of Alzheimer’s statistics from less developed countries. A recent study from China, for example, found dramatic under-reporting of Alzheimer’s. While this is certainly a plausible hypothesis, I think the wide variability in diagnosing Alzheimer’s stands in the way of this sort of comparison.

http://www.eurekalert.org/pub_releases/2013-09/uoc-bhi090413.php

http://www.theguardian.com/society/2013/sep/04/alzheimers-disease-link-hygiene

Full text freely available at http://emph.oxfordjournals.org/content/2013/1/173.full

Reference: 

Related News

A diet containing compounds found in green tea and carrots reversed Alzheimer's-like symptoms in mice genetically programmed to develop the disease.

A mouse study has found that canola oil in the diet was associated with worsened memory, worsened learning ability, and weight gain in Alzheimer's mice.

Periodontitis raises dementia risk

Aging linked to impaired garbage collection in the brain

Link found between chronic inflammation and Alzheimer's gene risk

A two-year study which involved metabolic testing of 50 people, suggests that Alzheimer's disease consists of three distinct subtypes, each one of which may need to be treated differently. The finding may help explain why it has been so hard to find effective treatments for the disease.

A post-mortem study of five Alzheimer's and five control brains has revealed the presence of iron-containing microglia in the

Analysis of post-mortem with and without dementia has found lipopolysaccharide, a component of an oral bacterium (Porphyromonas gingivalis), in four out of 10 Alzheimer’s disease brain samples, but not in any of the 10 brains of people who didn’t have Alzheimer’s.

Analysis of 700 subjects from the Alzheimer's Disease Neuroimaging Initiative has revealed a genetic mutation (rs4728029) that’s associated with people who develop Alzheimer’s pathology but don’t show clinical symptoms in their lifetime.

Blocking a receptor involved in inflammation in the brains of mice with severe Alzheimer’s produced marked recovery in blood flow and vascular reactivity, a dramatic reduction in toxic amyloid-beta, and significant improvements in learning and memory.

Pages

Subscribe to Latest newsSubscribe to Latest newsSubscribe to Latest health newsSubscribe to Latest news
Error | About memory

Error

The website encountered an unexpected error. Please try again later.