The Hyderabad-Deccan English Daily

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.



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

Add Comment

Enter the Numbers in the image

Latest Videos:
Cracker shops without license sealed at Mahboob Gunj, Hyderabad Santoshnagar police organized a huge health camp for public
Police Commemoration day 2014 celebrated at Madannapet police station Hyderabad Asaduddin Owaisi & Akbaruddin Owaisi in a press conference after winning 2 seats in Maharashtra

Related Articles:

Is your deodorant making your armpits smell worse? ..
Exercise cuts risk of developing painful gallstones ..
Friendly neighbours may be good for your heart ..
Include five daily portions of fruit, vegetables in your diet to ..
Link found between bacteria, white blood-cell cancer ..
76% of adults concerned about low hygiene standards ..
New gut insight for irritable bowel syndrome sufferers ..
Job loss, not recession, ups death risk ..
Fresh honey can provide alternative to antibiotics, says a study ..
Some oral myths debunked- Dental health ..

37% wash hands with soap 3-4 times: Study

Kolkata, Sept 27 (IBNS) Only 37% Indians wash their hands with soap 3-4 times a day, according to a latest study.

The Global Hygiene Council (G

Indians believe low hygiene standards make infections: Report

Kolkata, Dec 11 (IBNS): The Global Hygiene Council 2013 study has revealed that over three quarters (76 percent) of adults are concerned about themsel

Being tall, obese may boost blood clot risk in men

Washington, April 29 : You are more likely to develop blood clots if you are tall, obese and male, according to a new study.
Obesity is a well-kn

Coriander appears to have bacteria fighting capability

Coriander oil is capable of killing many strains of bacteria in laboratory tests, researchers have found.

Coriander, also called cilantro, is a

4 world class British cyclists pull out of Games

London, Sep 24: In the latest blow to the Delhi Commonwealth Games organisers, four top cyclists including world and Olympic champion Geraint Thomas h

Insulin may protect patients from fatal bacterial infections

Washington, Sept 9 : A new study has revealed that treating patients with insulin may reduce their chances of succumbing to an infection. University a

30 Minutes of Daily Exercise Ensures Healthier 2010

Just add 30 minutes of physical activity to your daily regime and ensure a healthier 2010, according to an expert. Peter Brubaker, professor of heal

IVF 'does not increase risk of cancer'

London, Dec 4 : A new study from the University of Lund in Sweden has shown that fertility treatment such as in-vitro fertilisation (IVF) does not inc

Cigarette smoking, alcohol use ups risk of upper aero-digestive cancers

Washington, Aug 3 : A study has found that a combination of heavy alcohol use and cigarette smoking is the key factor in increasing the risk of upper

Dabur Babool holds oral health campaign in Kolkata schools

Kolkata, July 18 (IBNS) : Dabur Babool on Wednesday announced the roll-out of a mega social campaign in West Bengal aimed at providing information on

'Patients with diabetes, hypertension may be at high risk of developing glaucoma'

Washington, August 18 : A study by researchers at the University of Michigan Kellogg Eye Center has indicated that individuals who suffer from diabete

Nutritional and food requirements for pregnant women

By Asima Azam(Dietitian): Pregnancy the most beautiful phase in a women's life,where there is increased need for all the nutrients such as calories,

Blood thinner ups stroke risk in some kidney disease patients on dialysis

Washington: The blood thinner warfarin should be prescribed with caution in some heart patients with kidney failure, say researchers who found that th

Lifestyle changes may reduce stroke risk

Dallas, June 8/2013 (IBNS) Making small lifestyle changes could reduce your risk of having a stroke, according to a new study in the American Heart As

Internet preferred for contacting government in Australia

Hyderabad Deccan News January 19/2012 : The internet is now well established as the preferred means of accessing government services, according to a s

Related News


Health News

WHO cautions: Do not let fox guard chickens

Bobby Ramakant, Citizen News Service (CNS)- This the first time ever when global tobacco treaty negotiations are taking place in Russian Federation. While sharing an internal tobacco industry document that is now in public domain, Dr Margaret Chan, Director General of the World Health Organization (WHO) said: "One record shows that there was an internal discussion whether the [tobacco] industry should consider children as part of its market. I remember very well one reply which I would like to quote: 'they have got lips, we want them'. They [tobacco industries] just want market share, they could not care less whether they are killing ch ... Read More
Latest Headlines

Dengue cases soar to 4,379 in Odisha

Teenage self-harm leads to mental health and substance misuse problems in adulthood

Smoking hampers neuro-cognitive recovery during abstinence from alcohol

Eating fruit and vegetables makes you happy and improves mental well-being

Spanish nurse cured of Ebola virus disease

Clinical trials of Ebola vaccine start Nov 1 in Switzerland: WHO

Indian psychiatrist Vikram Patel gets the 2014 Sarnat Prize in mental health

Injectable polio vaccine more effective than oral one: Experts

Surveillance-tracking system in India for checking Ebola: Health Minister Harsh Vardhan

Pakistan president Mamnoon Hussain orders steps against Ebola virus

Non-smokers face major health risks in smoking homes

Sugary drinks could lead to poor memory

An apple a day boosts sexual pleasure am

Yogurt shields pregnant women against he

Alcohol increases risk of common sexuall

This page was created in 0.449914932251 seconds