Asthma is a chronic lung disease characterized by recurrent episodes of breathing problems and symptoms such as breathlessness, wheezing, chest tightness, and coughing.

The symptoms of asthma, which can range from mild to life threatening, can usually be controlled with a combination of drugs and environmental changes. Between episodes, most patients feel fine. Right now according to WHO, around 300 million people suffer from asthma worldwide, especially in industrialized countries. The trend is increasing in developing countries. Over 30 million people in Europe have asthma, a number greater than the population of the Netherlands and Belgium combined. Throughout Europe, the prevalence of asthma is generally higher in urban areas compared with suburban and rural areas. More than 6% of children in the United States have been diagnosed with asthma. Asthma is usually diagnosed in childhood.

To better understand asthma a variety of information will be given on the following pages. Firstly the respiratory system will be explained, followed by a short overview regarding allergies. Afterwards asthma will be explained in a thorough and in-depth way, looking at what happens in an asthma attack and what are asthma's causes, regarding the possible treatments and newer research that is conducted in that area. Moreover recommendations for asthma patients will be given. This document concentrates on causes, mechanism and treatment of asthma.

When air is inhaled, the diaphragm (a sheet of muscle extending across the bottom of the rib cage) contracts. The contraction makes the lungs expand, allowing air to pass through the trachea and into the lungs. When air is exhaled, the diaphragm relaxes and arches upwards, thus pushing the air out of the lungs. As well as the diaphragmatic breathing, the respiratory system engages in thoracic breathing, whereby the ribs are lifted by the muscles of the intercostal space (the space between two ribs).

When air is inhaled, it goes into the alveoli via the bronchia. The alveoli are surrounded by capillaries (very small blood vessels). The oxygen in the inhaled air is transferred into the blood. The carbon dioxide is transferred from the blood into the alveoli and is then exhaled.

In the case of allergies, the immune system reacts to certain external substances. These substances, known as "allergens" can for instance be plant pollen, animal hair or house dust. In the case of an allergy, the immune system, which is meant to defend the body against germs, reacts to these harmless substances by mistake.

Allergies can manifest themselves in a multitude of different symptoms. Typical symptoms are: sneezing, reddened eyes, itching, rashes, coughing, difficulty breathing, swelling, shock (e.g. after being stung by an insect).

Allergy tests are carried out in order to determine which allergens a patient reacts to. There are different methods, for instance the "skin prick test" which is often used: In this, drops of allergen extracts are placed onto the skin. Then, the skin is scratched with a lancet so that the solution can enter the epidermis. Skin irritation is an indicator for an allergic reaction.

Avoidance of the allergens: If the patient does not come into contact with the specific allergens, no symptoms of the disease will occur. In some cases this is easily dealt with, e.g. with some food or pet allergies. With other allergens, however, avoidance proves to be difficult, e.g. with air-borne pollen or mould spores.

Allergy immune therapy: The goal of allergy immune therapy (also known as desensitization or allergy shots) is to reduce the patient's sensitivity towards the allergens. To achieve this, allergens are administered in gradually increased quantities. The body will slowly learn to tolerate the substance such that by the end of a successful treatment it will no longer respond to the substance or the allergic reaction will be less severe. For this type of treatment therapeutic solutions containing extracts of the respective allergens (e.g. various pollens, dust mites, animal dander, insect poisons, and mildews) are used.

Medications: The symptoms of allergies can be treated with medications, many of which reduce the effect of the histamine (antihistamines). Histamine, released by the immune system as messenger substance, is accountable for the typical symptoms of an allergy. Other medications (e.g. cortisone) protect the patient against inflammation, but can have side effects.

Asthma, the correct term being "bronchial asthma", is a chronic inflammatory disease of the respiratory system.

There is a difference between allergic asthma and non-allergic asthma. However, in many cases mixed forms occur.

Today, asthma is the most common chronic childhood disease in the industrialized countries.

Asthma is a genetically and environmentally induced disease. The two main predispositions for asthma is gender (being male for asthma in pre-pubertal children and female after puberty) and family history of asthma (up to 70% of cases have a family history of the disease). Interestingly, on the remote South Atlantic island Tristan da Cunha, 50% of the population are asthmatics due to heredity transmission of a mutation in the gene CC16. The islands have a population of about 270 people. The high incidence of asthma is largely caused by the inevitable marriages among related couples - for example marriages between second degree cousins.

Another reason for having asthma could be found in lifestyle: The prevalence of allergic asthma has increased decades earlier in Western Europe than in Eastern Europe. This is probably attributable to changes in lifestyle that had already occurred rather than to air pollution. The recent increase in asthma prevalence has been particularly marked in the former East Germany, which now has prevalence rates similar to those in former West Germany.

Similar increases are expected to occur in the former socialist countries of the Baltic region in coming years, as these communities increasingly adopt Western lifestyles.

There are many identified triggers of the disease such as:

Upon exposure to such a factor, the immune system overreacts as if it was fighting off a harmful parasite. It is thus an immunologically based disease. The exact reaction of the body in an allergic asthma attack will be explained on the next pages.

In an asthma attack, a narrowing of the respiratory passage will result in difficulty breathing. An attack may be caused for instance by inhaling provocative agents or by physical exertion and leads to an inflammation of the respiratory tract. Thereby the tube-like muscle surrounding the bronchia will contract. The inflamed bronchial mucous membrane swells, thus narrowing the airways. The glands in the mucous membrane increase their mucus production. This excess mucus, in conjunction with the narrowing airways, will ultimately lead to coughing, wheezing, and difficulty breathing: an asthma attack.

An asthma attack often starts with tightness in the chest. In many cases it is followed by continuous irritation of the throat and eventually acute breathlessness. This can result in a lack of oxygen and anxiety. Usaually exhaling feels difficult and is accompanied by wheezing sounds. An asthma attack can last from a couple of minutes up to several hours. Coughing is generally the main symptom for asthma in children.

The early life event phase is arguably the most interesting. This is because it is at this stage that the decision is made whether a person (with his/her specific genetic predisposition) will become ill with asthma during his or her lifetime. So the combination of the environment in the very early life stage and the genetics of a person seem to be a predictor for getting asthma. This means that a person could have a predisposition for asthma without ever showing the symptoms, because the person doesn't get in touch with the environmental triggers.

So research on the early life events answers the question why asthma starts. And consequently, what is causing it and how it can be prevented. The early life events are characterized by embryo exposure to mother"s immune system and by child's first three years exposure to the immediate environment. The first three years are important as they correspond to the time when lungs are still developing.

Before asthma sets in, patients usually suffer for a number of years from allergic rhetinitis (hey fever) or atopic dermatitis (type of a skin allergy). The disease often progresses from atopic dermatitis to allergic rhinitis and then to asthma. This evolution is known as "allergy march". However, there are cases where asthma can start without a warning. This usually happens in young children.

Allergic and asthmatic symptoms are associated with indoor and outdoor air quality. In 1999-2004, asthma prevalence in children across the European study centres varied from less than 5% to over 20%.

Children with asthma have long been recognized as particularly sensitive to outdoor air pollution. Many common air pollutants, such as ozone, sulfur dioxide, and particulate matter are respiratory irritants and can exacerbate asthma. Air pollution also might act synergistically with other environmental factors to worsen asthma. For example exposure to ozone may enhance a person's responsiveness to inhaled allergens. Whether long term exposure to these pollutants can actually contribute to the development of asthma is not known.

There are different agents that can initiate the sensitisation process in people. These are certain antibiotics and viruses. . They can act by different mechanisms. For example viruses may reduce epithelial defences whereas diesel particles cause T-cell activation. This period may last many decades. Some people may start to exhibit asthma only later in their lives. Interestingly, males get asthma earlier in life than women. Women however "catch up" when they are in their 50s. There is no satisfactory explanation for the male/female differences.

The main area of research both at universities and in pharmacological companies concentrates on treating asthma. But the progression of the disease, if triggered by allergens, is well understood. In case of allergic asthma stimulants that trigger allergies (allergens) cause an intense reaction of the immune system. The compounds produced by the body in the course of this reaction (e.g. histamine) can trigger asthma attacks. A closer look at this process of allergic asthma:

However, not all asthma attacks are caused by allergens, there are other triggers (see above).

When asthma is not effectively treated, the condition often leads to hospitalization, missed work and school, limitations on physical activity, sleepless nights and in some cases death. Both the frequency and severity of asthma symptoms can be reduced by the use of medications and by reducing exposure to the environmental triggers of asthma attacks.

Most drugs for treating asthma are made to be inhaled, so that the active agents can enter the bronchia and the branches. There are two different therapies for an asthma attack. One concentrates on relieving the symptoms once the attack occurs. Other therapies concentrate on inhibiting the later phases of the cascade that leads to asthma. There are numerous medications for alleviating these symptoms and in addition there are non-drug based treatments.

The two main types of drugs used for treating asthma are most commonly taken using an aerosol inhaler:

Bronchial dilators are more commonly referred to as bronchodilators. Dilators are meant to open the inflamed airway to give more breathing room.

There are a few types of bronchial dilators that act within minutes while their effect lasts for a few hours. Short acting forms that contain medications that cause instant dilation of the airway. Examples are: fenoterol, salbutamol, terbutaline, and the combination of ipratropium with fenoterol.

Long-acting forms of bronchodilators may be either inhaled or taken orally. These medications are no immediate relieve for asthma attack symptoms but are meant to prevent these from occuring. Most people will still need to keep a short-acting inhaler on hand in case an asthma attack develops. Examples are formoterol, ipratropium and salmeterol. These medications are now often combined with a steroid in order to be most effective. Examples are Advair and Symbicort.

Inhaled corticosteroids or anti-inflammatory drugs are the most effective and commonly used long-term control medications for asthma. These medications need to be taken for several days to weeks before they reach their maximum benefit and are mainly effective in the case of asthma induced by allergic reactions. Examples are: Fluticasone, Budesonide, Mometasone, Beclomethasone or Ciclesonide.

Adrenal cortex hormones, or corticosteroids may also be taken orally if a shock therapy is called for when asthma develops in spite of the use of proper medications. Examples are: dexamethason, prednisolon, prednison en triamcinolon.

It is often said that the main problem for asthma suffers is not the lack of medication or new compounds. The problem is that sufferers improperly use existing medications. Asthmatics sometimes stop taking their preventive medication when they feel fine and have no problems breathing. This often results in further attacks, and no long-term improvement.

Avoidance of the allergens - In the case of allergic asthma the respective allergens should be avoided as much as possible, which is easier for some allergens (e.g. pets, food) than for others (e.g. mould, polls).

Allergy immune therapy - As explained above, the objective of allergy immune therapy (also known as desensitization or allergy shots) is to reduce the patient's sensitivity towards the problematic allergens. At the end of a successful treatment the body will not respond to the substance any more or the allergic reaction will be at least less severe.

Behavioural changes - Apart from avoiding possible allergens, patients suffering from asthma should also refrain from smoking. Furthermore, minimal stress and a normal lifestyle are recommended.

Physiotherapy - In many cases, it makes sense to learn breathing techniques and relaxation exercises to aid in the therapeutic process.

Psychological care - Emotional aspects can contribute to asthma attacks. In this case, psychological consultation can be helpful.

At present there is no cure for asthma. However, asthma is treatable: medications, asthma management and education are improving all the time. Reducing exposure to environmental allergens and pollutants will reduce the frequency and severity of attacks for children with asthma, reduce their need for medicine, and improve their lung function.

Initially, large-scale epidemiological studies were carried out to establish which groups of persons suffer the most and which suffer the least from asthma.

Children who grow up in a farming environment show lower levels of atopic sensitization, hay fever, and asthma than children of the same age not living in such an environment. Some of the initial observations were made in the USA in the late 1980s. This was later termed the "hygiene hypothesis". The hygiene hypothesis states that children living in an environment with few germs are very often affected by allergies. It is thought that the coming into contact with many different agents during childhood plays a vital role in the formation of a "faultless" functioning of the immune system.

A number of investigations provided good evidence that this is due to an early-life contact with cowsheds, farm animals, and/or consumption of products like raw milk. Also, it had been suggested that micro-organisms might have an important effect on the development of allergies.The question thus arose which farm microbial organisms, their products, or both might induce or influence allergy-protective mechanisms.

Through animal testing scientists could demonstrate that the positive effect was most likely due to the barn dust. More detailed studies showed that specific bacteria contained in the barn dust provided, to a certain degree, protection against the development of asthma and allergies in mice. These recent research results indicate that Acinetobacter lwoffii and Lactococcus lactis strains, two types of bacteria that were isolated from farm cowsheds possess strong allergy-protective properties. In the film "Out of breath - understanding asthma" it is shown how these conclusions were reached and how the research was conducted.

There are not only environmental factors that play a role in the acquisition of asthma but also genetic factors. Specific genes may not be exactly identical in different individuals, which may result in slight to severe differences in functionality. There is no single "asthma gene". Many genes interact and slight differences may cause susceptibility to asthma. So far only a few genes have been identified as being correlated to asthma. Still, individuals may have one or more genes to predispose him/her to asthma without ever suffering from its symptoms. The genes may never be expressed because of lack of environmental stimuli. Because of the many interactions between genetic predisposition, environment and gene interactions, genetic research is very complicated.

In Arizona, researchers revealed a strong correlation between asthma and genetics when examining 344 families. Among families with neither parent having asthma only 6% of the children developed asthma, while in families with both parents having asthma 60% of the children had asthma.

Twins are excellent candidates for genetic research. In 1995 Sarafino and Goldfedder conducted research to prove that both genetics as well as the environment play a role in the contraction of asthma: among identical twins asthma occurred for 59% in both individuals. Among only 24% of the non-identical twins both individuals had asthma.

New technologies have brought possibilities to screen differences in individual genes among large groups of people. Researchers from the Molecular Epidemiology group at the GSF National Research Centre for Environment and Health in Neuherberg, near Munich, have been involved in such a large-scale study. By means of micro array technology, the research project tried to find the differences in the genotype of asthmatics and healthy people. The team examined over 300,000 genetic markers in thousands of asthmatic children and compared this data with those of healthy control groups. They identified a gene, named ORMDL3 which, in its modified version, may contribute to the risk of childhood asthma. The gene therefore is now a promising object of research: it could help to improve the prevention and diagnosis of asthma, and possibly to develop a new therapy.

A new drug is Omalizumab which is an immunoglobulin E monoclonal antibody to the (protein) product of the gene called ADAM33. The product of the gene has pro-inflammatory activity. The person who identified and characterized the gene is Stephane Holgate in Southampton, UK. It was the first new gene discovered in connection to asthma. Holgate thinks the gene is responsible for the muscle-development in the airway (but there is no direct connection between ADAM33 and asthma in all populations studied). This promising antibody therapy has just been marketed under the name of Xolair. Critics argue that this therapy has only a limited range of application, primarily in adults, since it can only be applied in individuals who have high levels of immunoglobulin-E.

Do not smoke - Smoking aggravates the symptoms of asthma. On principle, asthmatics should refrain from smoking.

Avoid allergens - Generally, asthmatics are familiar with the allergens that trigger their asthma attacks. These agents should be avoided. Moreover, they should be careful of any other allergens and stimuli that trigger or contribute to asthma attacks.

Take your medications regularly - Medications should be taken regularly and should not be discontinued without prior consultation with a doctor. Also, as the drugs are being continuously developed, it is advisable to confer with your doctor at regular intervals about the medication you are taking.

Breathing techniques and relaxation exercises - Certain breathing techniques and relaxation exercises help to prevent asthma attacks (e.g. autogenic training, meditation, yoga).

Exercise and sports - Strenuous physical exercise as well as a lack of exercise should be avoided. Recommended sports include hiking, walking or rowing. Cycling and particularly running can be problematic.

Protect yourself against colds and influenza - Influenza virus vaccinations, a diet rich in vitamins and regular physical exercise help to minimize the probability of acquiring such diseases. Try to avoid sick colleagues and exposure to draught.

Appropriate holiday destinations - Suitable holiday destinations are those with cleaner air and a lower pollen count, e.g. at the sea or in the mountains.

The ComScience project is a Cooperation Action (#230470) funded by the European Commission under the Seventh Framework Programme: FP7 - Capacities - Science in Society ComScience © 2009-12

May 18, 2012. NEWS Pollination with precision: How flowers do it Next Mother's Day, say it with an evolved model of logistical efficiency — a ... New technique reveals unseen information in DNA code This image shows the differences in chemical structure of the 5-methylcytosi (5mC) base (left) from ... Ancient giant turtle fossil revealed This is a reconstruction of Carbonemys preying upon a small crocodylomorph. Picture a turtle ... Abundance of rare DNA changes following population explosion may hold clues to common diseases One-letter switches in the DNA code occur much more frequently in human genomes than ... Unhurtful Thoughts: A Preoccupied Brain Produces Pain-Killing Compounds   ... Apple to Use Only Green Power for Main Data Center By Poornima Gupta(Reuters) - Apple Inc plans to power its main U.S. ... Job Killer? Try Bottom Line Booster: Workplace Safety Inspections Save Money, Jobs, Limbs Image courtesy of iStockphoto/lisafx Costly safety upgrades, nitpicky government inspection and resulting fines are ... Most Users Are App Freeloaders When's the last time you treated yourself to a new mobile app? Okay, when's ... Buried microbes exist at limit between life and death Sediment 30 metres below the Pacific seafloor is so nutrient-poor that microbes barely fuel ... Plutonium signature captured after 50 years of trying The complex properties of radioactive plutonium-239 made its structure hard to analyse – until ...     > More News ..