Different asthma categories
Various categories of asthma exist based on cause. Some of these definitions commonly used overlap and therefore are of limited value concerning a precise definition. Therefore at times multiple types of asthma can be present simultaneously. The most important categories are:
Extrinsic or allergic asthma: is caused by some factor in the environment, usually referred to as atopic asthma. Onset is usually in childhood and almost always before the age of 30.
Intrinsic or non-allergic asthma: is attributed to pathophysiological disturbances and not to environmental factors; it is usually seen in adults.
Mixed-type asthma: as its name suggests, this is a mixture of intrinsic and extrinsic asthma. Patients react to some allergens but their asthma is also triggered by other factors.
Exercise-induced asthma: is due to a narrowing of the airways occurring in moderate to heavy exercise
Nocturnal asthma: describes asthma, which suddenly worsens in the middle of the night, typically between 2 and 4am. Affected patients frequently feel totally exhausted during the day and need catnaps to keep functioning at an adequate level.
Occupational asthma: develops from a few months to years after starting a new job. Symptoms usually improve while on holiday. Some common causes include: sawdust, chemical fumes, constant dusty conditions, close contact with animals, glue fumes, etc.
Seasonal asthma: can be triggered by particular allergens, i.e. pollens from trees, grasses or flowers, or by a particular climate.
Literature:
O´Byrne P. GINA Executive Committee. Global strategy for asthma management and prevention. 2004. National Institutes of Health. Publication No 02-3659
