Boys 'grow out' of asthma
19 August 2008

Boys are more likely than girls to 'grow out' of childhood asthma symptoms when they hit their teenage years, according to research published in the American Journal of Respiratory and Critical Care Medicine.

In a study led by Dr Kelan Tantisira, experts at The Harvard Medical School tested more than 1,000 children’s lung function over an average of nine years. The children were aged between five and 12 and all had mild to moderate asthma. In annual tests they were given a drug to cause irritation of the airways and airway narrowing, and scientists noted the dosage that was needed to do this.

People with asthma react to lower doses of the drug generally, and this study showed that the amount of the drug needed in girls did not change much over time, however in many of the boys, bigger and bigger doses were needed year on year, suggesting that the severity of their asthma was decreasing. By the age of 18, only 14% of the girls did not react to the drug, compared with 27% of boys.

Leanne Male, Assistant Director of Research at Asthma UK, said: 'In the UK we have one of the highest rates of asthma in the world with 5.2 million people suffering from the condition. We know that asthma prevalence is higher among boys than girls but that the condition, later in life, is more prevalent in women than men.

'This study is particularly exciting as it provides an insight into the mechanisms involved in asthma development during the transition period between childhood and adulthood, demonstrating how we can influence these processes and develop new targeted therapies.

'Hormones can play a key role in influencing asthma symptoms and severity, suggesting that gender is an important factor in asthma development. This study is the first to take this theory to the next level by looking specifically at the nature of the airway responses involved.'