Asthma affects growing numbers of people



Asthma affects growing numbers of people





Asthma affects growing numbers of people

Evelyn Moore was 43 when asthma invaded her life. She was living in Montreal, where a doctor was treating her for hay fever brought on by tree pollens in the spring and fall. “And then one day,” recalls Moore, now 55 and a resident of North Bay, Ont., “I just got one heck of an asthma attack. I’ve been having them ever since.” Moore says that asthma now affects her whole life. “I have to watch where I go,” she says. “I have to stay away from crowds because of the risk of picking up any bugs, which would make my asthma worse. I have to watch out for yellow goldenrod in the summer and vacuum the house all the time to keep down the dust. Even with medication, my asthma is hard to control. Sometimes I can’t sleep because of my coughing and wheezing. And some days, the weather will be just beautiful—but I can’t even open the window because of what might come in. Asthma is a very big adjustment—it turns your whole life around.”

Over the past 25 years, asthma—a constriction of the airways causing coughing, wheezing and shortness of breath—has been disrupting more and more lives, around the world and in all age groups. An estimated 1.7 million Canadians, or about six per cent of the population, have the disease, up from about two per cent 15 years ago. And the fatality rate is rising: among Canadians aged between 10 and 34, deaths from asthma

have more than doubled since the early 1980s; in 1994, the affliction claimed about 500 Canadian lives. “What we have,” says Dr. Malcolm Sears, a professor of medicine at McMaster University in Hamilton, “is an illness that used to be considered a relatively mild disease—and now it’s killing people.”

Experts are not sure why more people are suffering, and sometimes dying, from asthma’s symptoms. Some scientists believe that the children of mothers who smoke are at greater risk of developing asthma— and surveys show that more young women are smoking. Other experts point to the prevalence of energy-efficient homes, which, while sealing in heat, also seal in asthma-inducing dust. And a growing number of experts think that some asthma victims die simply because their family doctors lack an adequate understanding of the illness and do not teach sufferers how to control it. Moreover, some researchers maintain that many asthmatics are putting themselves at risk through overuse of a family of adrenaline-like drugs called beta-agonists. The drugs are highly effective at halting wheezing attacks, but some researchers are convinced that if used too often, beta-agonists can actually pave the way for more serious attacks as patients develop a drug tolerance. “People tend to go for what gives them quick relief,” says Sears,

“without realizing that they may actually be aggravating their condition.”

The good news is that knowledge about asthmaand asthma medications—has improved to the point where many victims can live nearly normal lives. There are shining examples in the sports world: Susan Auch,

Mighty mites

Dust mites are so small they are invisible to the naked eye. But they can create serious problems for asthmatics. Dermatophagoides pteronyssinus (greatly magnified, above), as the creature is formally named, lives in mattresses, pillows, sofas and carpets, where it feasts on the particles of dead skin shed by humans. Dust mites do not bite or transmit disease, but their droppings contain a potent allergen and, if inhaled by an asthmatic, can trigger an attack of wheezing. Experts advise asthmatics to permanently enclose mattresses, box springs and pillows in plastic bags to deprive the dust mites of food. Unless such precautions are taken, the average Canadian bed may play host to as many as two million dust mites.

29-year-old speed skater from Winnipeg, and Renn Crichlow, the 26-yearkayaker from Nepean, Ont., both suffer from asthma and have both won a clutch of medals in international competition. “I got into skating,” says Auch, “because my doctor encouraged me to do sports—he thought that having strong lungs would help my asthma. And it has.”

For others, bouts of wheezing can make life an ordeal. It is particularly hard on children, a segment of the population in which asthma is growing rapidly. According to the Toronto-based Asthma Society of Canada, one in five Canadian children now suffers from asthma—a substantial increase over a generation ago. Nine-year-old Jon Crawford is asthmatic, and some of his worst suffering occurred when the Crawford family of northern British Columbia moved just 110 km southwest, from New Hazelton to Terrace, four years ago. When he first encountered the kinds of trees and grasses that grow around Terrace, recalls Jon’s mother, Sharon Crawford, he experienced a bad

attack at a time when she and her husband had not yet learned how to cope with his illness. “It was scary,” she recalls. “He would cough for about five minutes and then try to take a deep breath—but he couldn’t. He’d look at me, his eyes saying, ‘Aren’t you going to help me?’ And there was nothing we could do.”

In about 60 per cent of cases, asthma is genetic in origin: that means that if parents or grandparents are asthmatic, their children likely will be, too. About 60 per cent of asthmatics suffer from allergies, which trigger asthma attacks. In nonallergic asthmatics, attacks can be brought on by cold air or exercise. Asthma usually appears in childhood, but it can strike adults who have never before had asthma symptoms. And while children sometimes “outgrow” the asthma of their early years, the affliction can return in later life.

For the allergic asthmatic, the enemy may be everywhere. The substances that can trigger attacks include house dust, tobacco smoke, diesel fumes and other kinds of air pollution, tree and other plant pollens, perfumes, paints, chemicals, nuts, eggs and other foods and food preservatives and household pets—especially cats. “Cats,” says Dr. Pierre Ernst, a Montreal respirologist, “are a menace to society.” An

estimated 20 per cent of all asthma may be related to the victim’s workplace, where industrial chemicals, wood dust or varnishes can bring on attacks.

When an asthmatic starts gasping for breath, it is because the airways leading to the lungs have suddenly narrowed. The process begins when antibodies on the victim’s nose and throat cells decide that they have spotted an enemy intruder. The body’s immune system responds by releasing chemicals that squeeze the airways to keep the invader out. Some of the chemicals act immediately by causing a spasm in the airway muscles. But other immune system chemicals can take up to six hours to produce what doctors call a late-phase inflammatory response in the airways—and a second attack long after the first one has passed.

nderstanding that chain of events has enabled researchers to develop better asthma drugs. Most prominent are the so-called broncho-dilators, many of them involving beta-agonists, which can relieve an attack while it is happening, and anti-inflammatory medications, including powerful synthetic corticosteroids, which can help to prevent the next one.

Both groups of drugs carry some health risks. The beta-agonists include salbutamol (sold under the brand name Ventolin), fenoterol (Berotec) and terbutaline sulphate (Bricanyl). During the mid-1980s, Malcolm Sears, a medical researcher in Dunedin, New Zealand, who wondered why asthma appeared to be getting more serious, carried out a study involving 64 asthma patients who used beta-agonists four times a day—and found that over a six-month period, asthma in a majority of the patients actually got worse.

Subsequently, researchers at the Royal University Hospital in Saskatoon produced findings that suggested why overuse of betaagonists could cause problems. In a 19921993 study, the researchers found that when ^13 mildly asthmatic patients were treated 1 with an inhaled beta-agonist for two weeks, their sensitivity to allergens increased—and, as the patients’ tolerance grew, the drug became less capable of reopening constricted airways. As a result, the patients’ asthma became worse. What the findings showed, says Dr. Don Cockcroft, the University of Saskatchewan respirologist who headed the study, “is that the way we have been treating asthma may have something to do with the increasing number of hospital admissions—and deaths—brought on by asthma.” Despite the concerns about beta-agonists, no one is suggesting that they should be taken off the market—only that they should be used sparingly. “Beta-agonists are supergood at what they do,” says Cockcroft. “They are lifesaving drugs. But there is reason to think that they should be used as little as possible.” According to Stuart Wilson, a spokesman for Glaxo Canada Inc., which makes Ventolin, “beta-agonists are the best available medicine for managing acute asthma attacks. But they are not the only treatment for asthma, and they should not be used as though they were.”

Many physicians urge their patients to keep beta-agonists in reserve and rely on anti-inflammatory drugs, such as airway-clearing inhaled steroids. But there are health risks associated with steroids, as well. Injected or taken as tablets, steroids such as the widely used prednisone can, after years of use, cause a variety of side-effects, including weight gain, muscle wasting, high blood pressure and osteoporosis;

they can also stunt growth in children. For those reasons, most doctors reserve prednisone for patients with severe asthma, and treat milder cases with inhaled steroids, which have fewer sideeffects. Dorothy Flarder, a Camrose,

Alta., mother of three, says that she worries about her 15-year-old son, Joel, and the battery of medications—including steroids— needed to control his asthma. “He has been taking all these powerful medications for years,” she says,

“and we don’t really know what the long-term effects may be.”

Meanwhile, scientists are developing a new family of anti-inflammatory drugs that could ward off airway inflammation without causing any of the side-effects associated with steroids. Dr. Paul O’Byme, a clinical researcher at McMaster University, says that the new drugs will help asthmatics by blocking the action of leukotrienes—mediators released by the body’s immune system that are partly responsible for the inflammation that can cause one asthma attack to follow three or four hours after another. The new approach, says O’Byme, who helped to develop it, should be especially useful in preventing asthma induced by vigorous exercise, when hyperventilation can cause the release of leukotrienes—and a bout of wheezing. Several major drug companies have developed leukotriene-based asthma dmgs, which could start coming on the market during the next year or so.

In their search for the underlying factors behind the asthma explosion, most researchers—surprisingly—have so far mied out a major role for one likely culprit: outdoor air pollution. Even though urban smog, diesel fumes and industrial emissions can trigger wheezing attacks, there is little evidence to suggest that it is a major factor in the spread of asthma. Still, experts say that air pollution can sometimes trigger the onset of asthma in people who are genetically predisposed

to get the disease. And airborne chemicals can cause attacks in people who have asthma. Last week, Cynthia Marino, a 37-year-old Saint John, N.B., resident, who campaigned against air pollution in the city, died after a severe asthma attack. A fellow protester, Judy LeBlanc, blamed Marino’s death and a rash of asthma attacks in the city, on emissions from the city’s Irving Oil refinery. “Air pollution is not the cause of our problems,” said LeBlanc. ‘But it puts us in a position where the consequences can be fatal.”

Indoor air pollution may play a larger role in the spread of asthma, since the increase in energy costs that began during the late 1970s prompted householders to seal their houses more efficiently to prevent heat loss. The popularity of wall-to-wall carpeting and home humidifiers has played a role in creating a welcoming environment for some of asthmatics’ worst enemies—dust mites, the tiny spider-like creatures whose droppings are a powerful asthma allergen. The dander (dried saliva and skin particles) of household pets, especially cats, can also be a potent allergen. Then there is tobacco smoke: studies have shown that children exposed to secondhand smoke experienced more severe asthma attacks than those who are not. Other researchers have found evidence suggesting that the children of mothers who smoke tend to be more likely to develop asthma—though it is not clear why. “And young women are the only group where smoking is increasing,” says Dr. Kenneth Chapman, director of the Asthma Centre at The Toronto Hospital. “It seems so obvious— there must be a connection.”

Many experts believe that one of the keys to getting the asthma epidemic under control, and reducing the death toll, is better education—of asthmatics and their doctors. “What we have here,” Chapman says, “is a potentially lethal disease for which some patients are not being given adequate information.” To remedy that, Chapman helped set up the year-old Canadian Network for Asthma Care. The aim of the organization: to make sure that both doctors and their patients are better informed about asthma and its treatment—and to reduce the suffering and deaths wrought by a sometimes cruel affliction.



Island of asthma

Many asthma experts think that better treatments—and even a cure—will emerge when researchers gain a clearer understanding of the genetic factors responsible for perhaps 60 per cent of asthma cases. As a result, scientists around the world are searching for asthma-related genes. At the University of Toronto, a research team set up three years ago decided to study populations with a high incidence of asthma. The problem was where to begin. Dr. Noé Zamel, a U of T medical professor who specializes in pulmonary disorders, remembered reading about the tiny island of Tristan da Cunha, a British possession in the south Atlantic about 1,800 miles west of Cape Town, South Africa. The island has a population of about 300 that is distinguished by its law-abiding ways, its peculiar version of early 19th-century English—and by the fact that about half the islanders are asthmatic. “It seemed,” says Zamel, “the ideal place to start.” The trouble, initially, was that the island’s elected council wanted no part of Zamel’s proposed study. But after an exchange of faxed messages, and an offer of gifts, including musical and electronic equipment, the council finally agreed. In

October, 1993, Zamel and technician Patricia McClean took a ship to the island from South Africa (Tristan has no airport) and spent the next month taking blood samples from every islander over 7. At the same time, Zamel and McClean traced the family histories of the islanders. The task was simplified by the fact that all of Tristan’s inhabitants are the descendants of a Scottish soldier named William Glass, who settled there with his wife in 1817, and a handful of Dutch, Italian and American sailors, some of whom subsequently married into the Glass family.

Since his visit to Tristan, Zamel has collected data on highly asthmatic populations in other parts of the world, including the Brazilian city of Rio de Janeiro and the Chinese island of Nantian, about 150 miles southwest of Shanghai. Meanwhile, a laboratory in La Jolla, Calif., has begun processing the genetic material extracted from the Tristan da Cunha blood samples. Zamel says that when the laboratory identifies the genetic source of the islanders’ asthma, he plans to return to Tristan “to throw a big party. We hope that will be soon.”

M. N.