In Norway, the Prescription Database contains information on all prescription drugs dispensed since 2001, which creates a unique opportunity to address the issue of whether the diagnoses of ADHD and asthma are associated with each other, over a wide age range.
Looking at the complete Norwegian population in 2006, the authors found a “marked comorbidity between asthma and ADHD” – in other words, it is rather likely to have one disorder if you have the other. Moreover, as they pointed out, the likelihood to have asthma if you have ADHD increased the older the age, and was highest in women age 20-49 and men age 30-49. The authors suggested that smoking may play a part, and that advice against smoking should be given to children with ADHD in order to prevent the development of asthma later on. They also discuss the possible role of chronic inflammation and obesity in both these disorders.
NOTE: Looking at Figure 1, it was quite remarkable to see that less than 2% of male and female children up to 9 years old, and only a little over 2% of the boys age 10-19 were prescribed ADHD medications. Do they really have such a low occurrence of ADHD in Norway? Or do they tend to prescribe more non-stimulant medications such as antidepressants which were not included in this study?