Health at birth tied to ADHD risk

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Health at birth tied to ADHD risk

By Amy Norton

NEW YORK | Fri Feb 11, 2011 5:35pm EST

NEW YORK (Reuters Health) - A baby's health in the first minutes after birth may

be linked to his or her risk of developing attention-deficit hyperactivity

disorder (ADHD) later on, a new study suggests.

The findings, reported in the Journal of Pediatrics, suggest that the so-called

Apgar score assigned to all newborns in the first five minutes of life may give

some hint of a child's future risk of ADHD, a condition that involves attention

problems and impulsive behavior.

A newborn's Apgar score is based on several physical signs, including breathing,

heart rate and muscle tone. A score of 7 or higher is considered normal, with a

9 or 10 indicating that the baby is in the " best possible condition. "

In the new study, researchers found that among more than 980,000 Danish

children, the risk of developing ADHD climbed as Apgar scores dropped.

Compared with children whose scores had been a 9 or 10, those with a 5 or 6 had

a 63 percent higher risk of ADHD. And those with an Apgar of 1 to 4 had a 75

percent greater risk.

In the U.S., surveys have found that nearly one in 10 school-aged kids have been

diagnosed with the condition, according to the Centers for Disease Control and

Prevention.

Exactly what the new findings mean is unclear. An abnormal Apgar score could

reflect some sort of stress during pregnancy or birth -- like decreased oxygen

supply -- that might contribute to ADHD development down the road, the

researchers speculate.

" There may be a sharing of causes of low Apgar score and ADHD, but our analyses

do not point (to) any specific factor here, " Dr. Carsten Obel, one of the

researchers on the work, told Reuters Health in an email.

A number of studies have linked preterm birth to an increased risk of ADHD,

although the reasons aren't clear, noted Obel, of Aarhus University in Denmark.

Both preterm birth and a low Apgar score may be markers of less-than-optimal

fetal development, he explained.

The findings are based on Danish national registry data for 980,902 children

born between 1988 and 2001. Of those children, 8,234 were diagnosed with ADHD --

most of them boys.

Even after the researchers accounted for factors like preterm birth, family

income and mothers' smoking and education levels, the risk of ADHD was higher

among kids with Apgar scores below 7.

Still, the vast majority of children in the study were not diagnosed with ADHD,

regardless of Apgar score. And it's not clear whether the Apgar-ADHD link might

eventually have any practical implications.

In this study group, Obel said, the ability of a child's score to predict ADHD

was not that strong.

" We do not find that the predictive value is so good that we routinely should

inform parents who (have) a child with a low Apgar score about the higher risk

of ADHD, " Obel said.

Future studies, he said, could try to undercover the reasons for the link

between Apgar score and ADHD. Large population studies might also be able to

look at how combinations of factors -- like low Apgar score plus a family

history of ADHD -- come into play.