Early asthma link to ADHD
medwireNews: Children who develop asthma early in life have a significantly increased risk for attention-deficit/hyperactivity disorder (ADHD) later in childhood, show the results of a nationwide, prospective study.
The Taiwanese study, which included 11,470 children, found that a diagnosis of either asthma or allergic rhinitis before the age of 4 years independently increased the risk for ADHD over a mean of 10.3 years follow up.
Among 2294 children who were diagnosed with asthma in early childhood, the rate of ADHD diagnosis was 7.0% compared with 4.6% among age- and gender-matched controls, report Ya-Mei Bai (National Yang-Ming University, Taipei) and colleagues.
After adjusting for confounders, including other allergic diseases and urbanization, children with asthma had a 31% increased risk for ADHD. And, among children with allergic rhinitis the risk was 33% greater. However, atopic dermatitis was not associated with greater ADHD incidence and neither allergic rhinitis nor atopic dermatitis comorbidity increased ADHD risk among children with asthma.
Additionally, the authors note that children who lived in the least urbanized areas were significantly less likely to develop ADHD during follow up, with those in the most rural areas having a 53% reduced risk, and those living in the second most rural areas having a 40% reduced risk compared with those living in the most urbanized areas.
Despite numerous reports of an association between the development of asthma and ADHD, a recent systematic review concluded that it was "impossible" to draw conclusions about a temporal relationship or to attribute causation, owing to the methodologies of the studies.
Bai and colleagues say that several features of their study, including the prospective case-control design, large sample, and use of only physician-diagnosed ADHD and asthma, strengthen their findings.
"Our prospective study supported the previous cross-sectional findings that children with asthma presented a higher risk for having ADHD than the control group, even after adjusting for comorbid allergic diseases," they write in the Journal of Child Psychology and Psychiatry.
They add: "Further studies are required to investigate whether the prompt treatment of asthma and comorbid allergic diseases could prevent the development of ADHD or decreased ADHD symptoms."
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Kirsty Oswald, medwireNews Reporter