• Asthma
• stress

Asthma is a complex disease affecting a large proportion of the world's population,1 but despite decades of intensive biomedical and epidemiological research its aetiology and pathogenesis is still poorly understood. As a consequence, a single target for intervention has not (yet) been identified. Recent epidemiological studies have provided innovative theories of the aetiology of asthma, such as the hygiene hypothesis, which suggests that microbial exposures may reduce the risk of asthma.2 These have considerable potential to guide the development of feasible primary (and secondary) prevention options. However, given the complex gene-environment interactions3 and diverse asthma phenotypes,4 any single type of intervention is unlikely to prevent all, or even a substantial proportion of asthma cases - a ‘one size fits-all’ approach is unlikely to work. The reported link between emotional stress and asthma5 is, therefore, of great interest, as it provides a further candidate for primary (and secondary) prevention.

The first report linking emotions to asthma is believed to be by the Greek physician Hippocrates (460-357 BC), who stated that to prevent an asthma attack ‘the asthmatic should guard himself against his own anger’.6 Until the second half of the 20th century this remained the predominant view, that is, asthma was considered to be a psychosomatic disorder in which emotional stress was the key factor in its aetiology; the condition was therefore commonly referred to as ‘asthma nervosa’. For example, Henry Hyde Salter, in his treatise ‘On asthma: its pathology and treatment’ published in 1860, wrote that ‘asthma is essentially, and with perhaps the exception of a single class of cases, exclusively a nervous disease; the nervous system is the seat of the essential pathological condition’.7 With the recognition of causal environmental exposures such as pollen8 and house dust9 in the latter …