NEW YORK - Children who wet themselves are more than four times as likely as other kids to also have attention deficit/hyperactivity disorder (ADHD), according to the results of a new German study.
"I think a lot of us have known this for a long time," that children with ADHD also struggle with bladder control, said Dr. Peter Jensen, a professor of psychiatry and psychology and the vice chair for research at the Mayo Clinic in Rochester, Minnesota.
But there are few studies that have looked specifically at the link between the two disorders, said Jensen, who was not involved in the German research.
ADHD is a common behavioral disorder that involves problems paying attention and controlling impulses, and has been diagnosed in nearly one out of every 10 children in the United States.
About two or three out of every 100 seven-year-olds have daytime wetting accidents, the authors note in their study.
The researchers, led by Dr. Alexander von Gontard at Saarland University Hospital in Homburg, Germany, surveyed the parents of more than 1,300 children five to seven years old.
They found that 49 of the kids wet themselves during the day, and 18 of them -- nearly 37 per cent -- also had symptoms of ADHD.
Of the 1,194 children who did not have incontinence, just 40 of those -- or about three per cent -- screened positive for ADHD.
When the researchers took into account factors that might skew the numbers, such as younger age or a developmental disability, they concluded that the risk of ADHD among kids who wet themselves is four times greater than among their schoolmates.
The study, published in the Journal of Urology, did not determine whether one condition causes the other, nor if they share the same underlying causes.
Jensen said that ADHD is tied to a delay in brain maturation, and perhaps that delay could also affect good control over going to the bathroom.
Children with ADHD also struggle to manage multiple activities, and might neglect to address the urge to pee while they're occupied with other tasks, he speculated.
Previous studies have found a link between ADHD and bed wetting, but the current study did not see a higher risk for ADHD among kids who had accidents at night.
The authors write that earlier work might not have factored in developmental problems in the children studied, which could increase the proportion of children who wet the bed.
The authors point out that "in clinical practice children with (incontinence) and ADHD have a much lower response rate to treatment than those with incontinence alone due to a lower compliance."
Jensen told Reuters Health this means that physicians and parents need to have more patience in treating wetting problems among children with ADHD.