Even though asthma was first described over 2,500 years ago, why some people develop it, and why some have it worse than others, remains a mystery. Yet by observing trends between male and female asthmatics, researchers now suspect a link between asthma and a hormone called testosterone.
Researchers have been studying asthma for many years now, and are well aware of the following trends regarding male and female asthmatics.
Boys are more likely to have it than girls.
During teenage years this trend reverses, and women are more likely to have it than men.
Women are more likely to have allergic asthma.
Women are more likely to have difficulty controlling asthma.
Therefore, women are more likely to suffer from more severe asthma than men.
Women are also more likely to develop adult onset asthma.
Women are more likely to have an adverse reaction to drugs.
Some experts speculate these trends may be due to a male sex hormones (androgen) called testosterone. It is produced in the testes of males and ovaries of females. How much testosterone is produced is determined by the hypothalamus and pituitary gland at the base of the brain.
When the hypothalamus determines testosterone levels are low, a signal is sent to the pituitary gland to release a hormone called Luteinizing hormone (LH), which causes the testes or ovaries to produce testosterone. When the hypothalamus determines testosterone levels are high, a signal is sent to the pituitary gland to decrease LH production, which in turn decreases testosterone production.
Testosterone is present early on in human development and is responsible for the development of male sex organs. During puberty, testosterone levels significantly increase, resulting in boys becoming men. It later plays a role in the development of sperm cells, abdominal fat, and hair loss. It impacts bone density, muscle growth, and libido (sexual desire).
The hormone is produced in significantly lower levels in women than men. It is for this reason that testosterone has been studied in recent years to see if it is the reason why asthma affects women worse than men.
Experts surmise testosterone to be linked with asthma because evidence suggests the hormone (or one of its metabolites) may also play a role in maintaining a balance between:
Autoimmunity. Your bodies ability to fight off invading viruses, bacteria, and parasites
Protective Immunity. Immunity from infectious diseases developed by previous exposure to the infecting agent
Testosterone accomplishes this by preserving the number of regulatory cells, or T-cells, which are important for the development of asthma. They are a type of white blood cell that form in bone marrow and mature in the thymus gland in the brain. They roam the blood looking for invaders, such as viruses and bacteria, that may be harmful to cells and cause diseases.
Asthma and allergies are the result of an overactive immune system, whereby T-cells attack substances that are innocuous (harmless). A good example of this is the allergic response. The first time you’re exposed to an allergen (say dust mites) your body produces T-cells specifically trained to recognize dust mites.
The next time you inhale dust mites, these specially trained T-cells recognize the allergen and set off an immune response that causes inflammation of the cells lining your respiratory tract. This is what causes allergies and allergy attacks.
This inflammation becomes chronic over time, making your airways hypersensitive to allergens, strong smells, emotions, smoke, pollution, and certain weather conditions. This is what causes asthma and asthma attacks.
The theory holds that testosterone is an immunosuppressant: it suppress the immune response responsible for it becoming overactive. In other words, it prevents allergies and asthma.
Rising testosterone levels in asthmatic teenage boys may suppress the allergy and asthma response, making their asthma less severe and more easy to control than their female counterparts. The theory also holds that higher testosterone levels may make it less likely that adult males will develop adult onset asthma than females.
A few studies have shown that administering testosterone to boys with asthma resulted in better lung function, although more studies are needed to confirm these results. Still, the main concern at the present time is the safety of administering testosterone to boys, as it may result in unwanted side effects (like accelerated bone maturation).
Researchers will continue to study the link between testosterone and asthma with the hope that this may lead to better treatment options, better asthma control, and ideally an eventual cure.
Further reading and references.