Newswala.com - The Best Source for online news
The Hyderabad-Deccan English Daily
Anmol Ratan - May Solve BP and Sugar Problems

Good hygiene may increase Alzheimer's risk, due to greatly reduced contact with bacteria


Good hygiene may increase Alzheimer's risk, due to greatly reduced contact with bacteria

London, Sept 20 (IBNS) People living in industrialised countries may be more likely to develop Alzheimer's due to greatly reduced contact with bacteria, viruses and other microorganisms - which can lead to problems with immune development and increased risk of dementia, suggests a new study.

New research has found a "very significant" relationship between a nation's wealth and hygiene and the Alzheimer's "burden" on its population. High-income, highly industrialised countries with large urban areas and better hygiene exhibit much higher rates of Alzheimer's.

Using 'age-standardised' data - which predict Alzheimer's rates if all countries had the same population birth rate, life expectancy and age structure - the study found strong correlations between national sanitation levels and Alzheimer's.

This latest study adds further weight to the "hygiene hypothesis" in relation to Alzheimer's: that sanitised environments in developed nations result in far less exposure to a diverse range of bacteria, viruses and other microorganisms - which might actually cause the immune system to develop poorly, exposing the brain to the inflammation associated with Alzheimer's disease, say the researchers.

"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, lead author of the study and Gates Cambridge Alumna, who conducted the research at Cambridge's Biological Anthropology division.

"There are important implications for forecasting future global disease burden, especially in developing countries as they increase in sanitation."

The researchers tested whether "pathogen prevalence" can explain the levels of variation in Alzheimer's rates across 192 countries.

After adjusting for 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% higher Alzheimer's rates than countries where less than half have access, such as Kenya and Cambodia.

Countries that have much lower rates of infectious disease, such as Switzerland and Iceland, have 12% higher rates of Alzheimer's compared with countries with high rates of infectious disease, such as China and Ghana.

More urbanised countries exhibited higher rates of Alzheimer's, irrespective of life expectancy. Countries where more than three-quarters of the population are located in urban areas, such as the UK and Australia, exhibit 10% higher rates of Alzheimer's compared to countries where less than one-tenth of people inhabit urban areas, such as Bangladesh and Nepal.

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

Researchers said that, although these trends had "overlapping effects", they are a good indication of a country's degree of hygiene which, when combined, account for 42.5% of the "variation" in countries' Alzheimer's disease rates - showing that countries with greater levels of hygiene have much higher Alzheimer's rates regardless of general life expectancy.

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 - supporting the new study's findings.

The results of the study are newly published by the journal Evolution, Medicine and Public Health, with these latest results coming hard on the heels of previous researchled by Fox on the benefits of breastfeeding for Alzheimer's prevention.

"Exposure to microorganisms is critical for the regulation of the immune system," write the researchers, who say that say that - since increasing global urbanisation beginning at the turn of the 19th century - the populations of many of the world's wealthier nations have increasingly very little exposure to the so-called 'friendly' microbes which "stimulate" the immune system - due to "diminishing contact with animals, faeces and soil."

Aspects of modern life - antibiotics, sanitation, clean drinking water, paved roads and so on - lead to lower rates of exposure to these microorganisms that have been "omnipresent" for the "majority of human history", they say.

This lack of microbe and bacterial contact can lead to insufficient development of the white blood cells that defend the body against infection, particularly those called T-cells - the foot soldiers of the immune system that attack foreign invaders in the bloodstream.

Deficiency of anti-inflammatory ("regulatory") T-cells has links to the types of inflammation commonly found in the brain of those suffering with Alzheimer's disease, and the researchers' proposal that Alzheimer's risk is linked to the general hygiene levels of a nation's population is reinforced by their analysis of global Alzheimer's rates.

"The increase in adult life expectancy and Alzheimer's prevalence in developing countries is perhaps one of the greatest challenges of our time. Today, more than 50% of people with Alzheimer's live in the developing world, and by 2025 it is expected that this figure will rise to more than 70%," said Fox.

"A better understanding of how environmental sanitation influences Alzheimer's risk could open up avenues for both lifestyle and pharmaceutical strategies to limit Alzheimer's prevalence. An awareness of this by-product of increasing wealth and development could encourage the innovation of new strategies to protect vulnerable populations from Alzheimer's."

While childhood - when the immune system is developing - is typically considered critical to the 'hygiene hypothesis', the researchers say that regulatory T-cell numbers peak at various points in a person's life - adolescence and middle age for example - and that microorganism exposure across a lifetime may be related to Alzheimer's risk, citing previous research showing fluctuations in Alzheimer's risk in migrants.

The team used the disability-adjusted life year (DALY) rates to calculate the incidence of Alzheimer's across the countries studied. The DALY measurement is the sum of years lost due to premature mortality combined with years spent in disability - the World Health Organisation (WHO) says that one DALY can be thought of as "one lost year of 'healthy' life".

The researchers say this method is a much better measure than death rates as it "omits the effects of differential mortality rates" between developed and developing countries. The study was based on the WHO's 'Global Burden of Disease' report, which presents world dementia data for 2004.





2013-09-20




Comments


No comments yet! Be the first one to leave a comment.


Add Comment

Name:
Comment:
Enter the number in the image on the right Enter the Numbers in the image

Related News

     
     

Health News Travelling with a smoker increases cancer risk
Travelling with a smoker increases cancer risk New York, Nov 16, 2014: While simply sitting in cars with people who smoke, non-smokers breathe in a host of potentially dangerous compounds that are associated with cancer, heart disease and lung disease, says a new research.

In a small yet significant study, 14 non-smokers sat for one hour in the passenger seat of a parked sport utility vehicle behind a smoker in the driver's seat.

The non-smokers showed elevated levels of butadiene, acrylonitrile, benzene, methylating agents and ethylene oxide (carcinogens and other toxins) in their urine.

This group of toxic chemicals is "thought to be the most important among the tho ... Read More
Latest Headlines
Right Arrow Quarantined Indian's samples found negative for Ebola
Right Arrow Tooth enamel fast-track found in humans
Right Arrow Rich elderly in Kerala check into medical-care centres
Right Arrow Golf courses are hotspots for ticks
Right Arrow Plague kills 40 in Madagascar
Right Arrow Ebola virus could be contained by mid-2015: Ban Ki-moon
Right Arrow Bird flu hits third poultry farm in Netherlands
Right Arrow Francois Hollande to visit Guinea next week, focus on fighting Ebola
Right Arrow Spanish health worker flown home after possible Ebola contagion
Right Arrow WHO declares DRC Ebola-free
Right Arrow Swedish health minister Gabriel Wikstrom to visit India
Diets do not work, lifestyle changes work: Lifestyle Coach Luke Coutinho conducted a Workshop for FICCI members at Hotel Hyatt,Hyderabad
Diets do not work, lifestyle changes wor
Walnut-rich diet may lower risk or preventing Alzheimer's disease altogether
Walnut-rich diet may lower risk or preve
How to prevent Urolithiasis or formation of urinary stones through diet
How to prevent Urolithiasis or formation
Probe irregularity in medical college admissions: Himachal Pradesh High Court
Probe irregularity in medical college ad
This page was created in 0.156252145767 seconds