In Utero Oxygen Deprivation Linked to ADHD Risk

Deborah Brauser

December 18, 2012

In utero oxygen deprivation may be associated with the later development of attention-deficit/hyperactivity disorder (ADHD), new research suggests.

A records review study of almost 82,000 children showed that those who had any prenatal exposure to ischemic-hypoxic conditions (IHCs) had a 16% greater risk of developing ADHD than their peers who were not exposed.

In addition, when assessing specific IHCs, the investigators found that the children exposed to preeclampsia had a 34% greater risk of developing ADHD, and those exposed to birth asphyxia had a 26% greater risk.

Dr. Darios Getahun

"Our findings showed that certain acute as well as chronic conditions are associated with this increased risk of ADHD later in life," lead author Darios Getahun, MD, PhD, research scientist and epidemiologist at the Kaiser Permanente Southern California Department of Research and Evaluation in Anaheim, told Medscape Medical News.

"Any finding that deals with brain development is very important," said Dr. Getahun. He added that the results could help clinicians to better identify at-risk newborns who could benefit from surveillance and early diagnosis "when treatment is more effective."

The study was published online December 10 in Pediatrics.

Exposures Lead to Greater Risk

For this study, the investigators evaluated electronic health records from Kaiser Permanente for 81,678 children between the ages of 5 and 11 years. Of these, 13,613 had a diagnosis of ADHD (74.3% boys).

Results showed that the children who had been exposed to IHCs had a significantly greater chance of developing ADHD than the children who were not exposed (adjusted odds ratio [AOR], 1.16; 95% confidence interval [CI], 1.11 - 1.21).

An increased risk of developing ADHD was also found for the children who were specifically exposed to preeclampsia (AOR, 1.34), birth asphyxia (AOR, 1.26), and neonatal respiratory distress syndrome (AOR, 1.47).

All associations remained significant across all race and ethnicity groups. Other associations with ADHD development were found for preterm birth, breech or transverse deliveries, deliveries that had cord complications, and placenta abruption before 34 weeks.

"Previous studies have found that hypoxic injury during fetal development leads to significant structural and functional brain injuries in the offspring," said Dr. Getahun in a release.

"However, this study suggests that the adverse effect of hypoxia and ischemia on prenatal brain development may lead to functional problems, including ADHD," he said.

He noted to Medscape Medical News that because the study was based on records data and the investigators were unable to continue following these children to evaluate their long-term risks for ADHD, he hopes that a prospective study in additional settings will be conducted soon to look at these issues.

The study was funded by Kaiser Permanente Direct Community Benefit funds. The study authors have disclosed no relevant financial relationships.

Pediatrics. Published online December 10, 2012. Abstract