Childhood asthma linked to hyperactivity/impulsivity
MedWire News: Results from a Swedish study suggest that children with asthma are at increased risk for the hyperactivity/impulsivity (HI) dimension of attention-deficit hyperactivity disorder (ADHD).
Asthma and ADHD are common disorders in children and may be associated, but previous studies of a possible relationship between the two conditions have produced conflicting results, say Catarina Almqvist (Karolinska Institute, Stockholm) and team.
In addition, "none of the previous studies have distinguished between the two DSM-IV ADHD symptom dimensions, which is a critical issue as HI and inattention (IN) have partly distinct etiologies and developmental outcomes," they add.
To investigate further, the researchers studied data on 1480 twin pairs born between 1985 and 1986.
Information on birth weight, parental socioeconomic status, and zygosity was obtained from the Swedish Medical Birth Register, while data on asthma, the use of asthma medications, and the presence of ADHD symptoms (HI and IN) were collected from parental questionnaires when the twins were aged 8-9 and 13-14 years.
The researchers found that children with asthma at the age of 8-9 years were a significant 1.88 times more likely to have at least one HI symptom and 2.73 times more likely to have at least three HI symptoms at the age of 13-14 years compared with those without asthma at the age of 8-9 years.
The findings remained consistent and significant after accounting for gender, socioeconomic status, birth weight, and previous symptoms of inattention and hyperactivity.
There was no significant association between childhood asthma and risk for IN symptoms, however.
Twin modeling analyses suggested that 68% of the phenotypic correlation between asthma and HI was due to genetics.
Almqvist and colleagues conclude in the journal Allergy: "Our findings suggest that childhood asthma is associated with subsequent development of HI in early adolescence, which could be partly explained by genetic influences."
They add: "Early strategies to identify children at risk may reduce burden of the disease in adolescence."
By Mark Cowen