The number of US children diagnosed with asthma, allergy and ADHD at the same time is increasing. Research indicates a link between these diseases, reports a review of the Annals of Allergy, Asthma & Immunology.

ADHD is a disorder that is more common in boys, as is asthma. ‘We observed that there is an increased risk of developing ADHD in boys with a history of asthma and, to an even greater extent, with lactose intolerance,’ says study author Eelko Hak from the University of Groningen.

The Dutch-American team of researchers analysed data on 884 boys with ADHD and 3536 boys without the disorder. In the first group, 34 per cent of the children had asthma and 35 per cent had allergies. The researchers suspect that the increased risk of ADHD may be related to the effects of asthma medication.

Allergies and asthma are often hereditary. If the parents are allergic, the chance that the child will also suffer from allergies is 75 per cent. It is estimated that 60 to 80 per cent of children with asthma have allergies. However, learning more about the relationship between ADHD and asthma and allergy requires more extensive research, the researchers conclude. (PAP)