Listen to this story:https://www.spectrumnews.org/wp-content/uploads/2023/07/ChangeOfHeart.mp3 Congenital heart malformations used to be a death sentence for many newborns. But as medical care and surgeries have improved, most infants born with heart defects -nearly 1 in 100 babies in the United Stateslive to adulthood. As they do, another matter has come to light: As many as half of people with congenital heart disease (CHD) have neurodevelopmental issues such as autism.Having CHD may raise the chances of being diagnosed with autism by anywhere from about onethird to sixfold, according to estimates from the past five years; A 2023 meta-analysis of all previous studies pegged the increased likelihood at twofold. Many children with CHD also have some traits that resemble autism but don't merit a diagnosis, such as problems with theory of mind and executive function, which includes working memory, cognitive flexibility, planning and self-regulation. "There's also the question of what do we do with everything that lies in between," says Johanna Calderon, chair in neurodevelopment at the University of Montpellier in France and lead scientist of the Cardiac Neurodevelopmental Team at the French National Institute of Health and Medical Research.Scientists used to think that these neurodevelopmental issues stemmed from the life-saving surgeries that infants with CHD typically undergo. Techniques such as deep hypothermia to achieve circulatory arrest and circulating the blood externally were thought to damage the brain by reducing blood flow to it or causing blood clots.