Asthma Epidemic: No one has the answers.

[Guest guest]

 

November 28, 2006

Second Opinion

An Epidemic No One Understands By DENISE GRADY

http://www.nytimes.com/2006/11/28/health/28seco.html

Our sons were born in 1984 and 1987, and we encountered an awful lot of

children their ages who had the same illnesses, far more than we remembered from

our own generation.

Statistics suggest that something strange was occurring in those years. From

1980 to 2003, the prevalence of asthma in children rose to 5.8 percent from 3.6

percent, an increase of about 60 percent, according to the Centers for Disease

Control and Prevention.

 

Other estimates from the disease centers show an even bigger increase in the

asthmas rates for younger children: a 160 percent jump in those younger than 5

from 1980 to 1994. But changes in data collection starting in 1997 make it hard

to compare the figures before and after that year. More recently, the rates seem

to have leveled off in the United States and in other Western countries. In any

case, about 20 million people in the United States have asthma today, including

at least 6 million children, and 5,000 people a year die from it.

 

Children in the inner cities seem to be especially hard hit, with exposure to

cockroaches and diesel fumes suspected as the culprits. But the cause is not

known for sure.

 

Worldwide, the disease has also increased. From 1985 to 2001, the prevalence

rose 100 percent. About 300 million people have asthma, 255,000 die from it, and

deaths could increase by 20 percent over the next 10 years, according to the

World Health Organization. The problem is especially severe in developing

countries, which are least able to provide the long-term intensive treatment

that asthma requires.

 

Some of the apparent increases may not be real, but may have occurred because

doctors got better at making the diagnosis. But increased reporting seems

unlikely to account for all the new cases. Theories come and go, and when you

come right down to it, no one really knows why some people develop asthma and

others don’t.

 

In “The Asthma Epidemic,” an article published last week in The New England

Journal of Medicine, doctors tried to sort out various theories about the causes

of asthma and explain why rates have risen. But there are no clear-cut answers.

 

Like other chronic diseases, asthma is probably caused by multiple genes and

environmental exposures, and it can have quite different causes in different

people. About half the cases are thought to stem from allergies and the rest

from other problems that can irritate and inflame the airways, causing them to

close.

 

Genetic changes in the population cannot explain the increasing rates, though,

because such changes occur too slowly to account for the rapid increases in

asthma, the authors said, suggesting that environmental factors are more likely

candidates. But what has changed enough in the environment to explain spiking

asthma rates?

 

The authors of the article, from University Children’s Hospital in Munich,

review many study findings. They report that one clear risk factor is secondhand

tobacco smoke. Exposure to it does increase asthma risk in infants and small

children. But how would that explain the increases, when over all, parents today

smoke less than previous generations?

 

People frequently blame air pollution for causing asthma, but its role is not

entirely clear. Pollution does makes asthma worse in people who already have the

disease, but it’s not known whether pollution also makes asthma develop in the

first place. And in any case, air pollution in the United States has decreased

in the last few decades. Living in a place with high vehicle exhaust may make

asthma worse, but the evidence is “relatively weak,” the researchers report.

 

Dust mites, microscopic insects that live in bedding and furniture, were long

blamed for causing asthma to develop in infants and small children and have led

to a booming industry of mattress covers, air filters and guilt-ridden parents

tethered to dust mops and vacuum cleaners. But recent studies have questioned

the connection. Once children have asthma, though, the mites and their droppings

may make the symptoms worse.

 

Cat dander has become a complete puzzle, with some studies finding that

exposure early in life leads to asthma, and others saying it protects against

asthma. At this point, nobody knows which study to believe, but most experts

agree that when people already have asthma, being around cats can make it worse.

 

Under some of the theories, I should have had the world’s worst asthma.

Clearly, I had allergic tendencies, and the experts would have shuddered at my

environment. I grew up in New York in a small apartment with parents who were

heavy smokers, on a busy street with trucks rumbling by and a bus stop in front

of the door. Buildings all around us burned coal. At times, we had a dog, a cat,

parakeets and, briefly, a duck. It’s amazing that the pets survived the smoke.

My mother was a decent housekeeper, but she wouldn’t have won any prizes. I

never wheezed. Go figure.

 

Obesity and asthma have also been linked in some studies, but the link, if it

exists, is not understood. Researchers say it is simply not a matter of

asthmatic children growing fat because they cannot exercise. The weight gain can

be first.

 

Nutrition is another mystery. Studies of fruits, vegetables, cereals, fatty

acids, vitamins, minerals and antioxidants have been inconclusive, and little is

known about the effects from what pregnant women eat. Experiments in which

pregnant women avoided cow’s milk and eggs in hopes of preventing asthma in

their infants did not work, and breast-feeding doesn’t prevent the disease,

either.

 

One theory that has received attention recently is the “hygiene hypothesis,”

the idea that children today are raised in homes that are too clean and that

asthma is somehow caused by the lack of exposure to infections and bits of

microbes early in life. Under this theory, germs are supposed to help the immune

system develop normally, and without them the system may overreact to other

substances in the environment, producing allergies and asthma.

 

There is some evidence to support the idea. Studies find that children raised

on farms are less prone than others to asthma, maybe because they are exposed to

plenty of microbes in barns and stables. But the connection is still not fully

understood, and some viral infections clearly make asthma worse.

 

A related idea is that the increased use of antibiotics in recent decades

contributes to asthma by changing the type of the bacteria that live in the gut.

But that has not been proved. Some researchers have suggested that

acetaminophen, used to treat pain and fever, may be linked to asthma. Its use

increased in the 1980s, after pediatricians declared aspirin unsafe for

children. But that theory has not been proved, either.

 

Ultimately, this new list of the usual suspects still doesn’t solve the

mystery.

 

 

 

 

It seems that we may almost have a double standard as far as medical theories

are concerned. As long as man does something, it's science. When nature does

something, it's quackery.

- Dr G E Poesnecker, (Nature Cure 2000).

 

 

 

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