OAKLAND, CA - Four times as many children have been diagnosed with autism in the past two decades amid improved awareness and screening and evolving definitions. A new study suggests diagnoses have increased at a faster clip among younger adults over the past decade. Autism spectrum disorder spiked 175% among people in the U.S. from 2.3 per 1,000 in 2011 to 6.3 per 1,000 in 2022, researchers found. Diagnosis rates climbed at a faster rate among adults in their mid-20s to mid-30s in that period, according to a study published Wednesday in JAMA Network Open. Researchers involved in the study set out to assess how many adults had been diagnosed with autism because earlier studies largely focused on school-age children, said Luke Grosvenor, the study's lead author and a postdoctoral fellow at Kaiser Permanente's Northern California research division. "There has been a shortage of research focused on autistic adults," Grosvenor said. Children ages 5 to 8 had the highest autism rate at 30.3 diagnoses per 1,000 children…